CA1103634A - Roadside barrier reflector - Google Patents
Roadside barrier reflectorInfo
- Publication number
- CA1103634A CA1103634A CA312,679A CA312679A CA1103634A CA 1103634 A CA1103634 A CA 1103634A CA 312679 A CA312679 A CA 312679A CA 1103634 A CA1103634 A CA 1103634A
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Abstract
ABSTRACT
An improved roadside marker system wherein each individual reflector means is longitudinally spaced from others thereof and is continuously visible by the driver of a vehicle moving along the road at night-time from viewing angle of 0 to 60° where 0° extends substantially parallel to a tangent to the road side portion in the region where each respective one of the reflector means is located. The driver continuously sees retroreflected light at any given instant of time while approaching and passing a group of the reflector means so employed and so located. Also, an improved roadside reflector assembly useful in such system which when mounted alongside a road is continuously visible by retroreflected light by the driver of a vehicle moving along the road at night-time within a viewing angle of from about 0 to 60° relative thereto, where 0° extends substantially parallelly to a tangent to the road in the region where such reflector assembly is located.
An improved roadside marker system wherein each individual reflector means is longitudinally spaced from others thereof and is continuously visible by the driver of a vehicle moving along the road at night-time from viewing angle of 0 to 60° where 0° extends substantially parallel to a tangent to the road side portion in the region where each respective one of the reflector means is located. The driver continuously sees retroreflected light at any given instant of time while approaching and passing a group of the reflector means so employed and so located. Also, an improved roadside reflector assembly useful in such system which when mounted alongside a road is continuously visible by retroreflected light by the driver of a vehicle moving along the road at night-time within a viewing angle of from about 0 to 60° relative thereto, where 0° extends substantially parallelly to a tangent to the road in the region where such reflector assembly is located.
Description
~1~36;~4 SPECIFICATION
Heretofore, in order to mark or delineate for visibility at night time by vehicle drivers road side edge portions (or road side edge barriers, or road median strips delineating the space interval between tWO ad~acent highway surfaces running parallelly to one another, or curved exit or entrance ramps associaced with so~alled super highways and other roadways, or tunnels, or bridge structures, or any hazardous object along a road), it has been conventional to employ vertically oriented reflectors. In general, three types of prior art reflectors have been employed for this class of application: (1) the prismatic triple mirror type reflector using a plurality of standard reflex type units where-in the individual cube axes are perpendicular to the suxface of the reflector; (2) the glass bead-type reflector sheeting wherein glass beads are embedded thereinto; and (3) the prismatic triple mirror type reflector using a plurality of angled cube corner-type retroreflective units (such as a reflector adapted from the teachings of Heenan [l.S.Patent 3,332,327) which is normally mounted horizontally on the pavement as a center line marker or the like, but which in this application is mounted vertically and which here employs only the front ramp-like surface of such reflector body). In this class of application, the performance of all three of these reflectors is sim.ilar to one another in that the peak of retroreflectivity of each type in terrns of light intensity when such is so mounted upon a road side edge or the like in a vertical orientation is parallel to a tangent to the road at that point. Retroreflectivity extends from chat parallel position ~sometimes termed 0), or from such a peak intensity location, -1 - , ~
through typically angles up to about 25 to 30 into the roadway, although the glass bead-type reflector sheecing appears to have slightly more angular range than this, going up to perhaps about 4oo.
S In all known such prior art types of reflectors adapted for this class of application, the reflected light output, or performance of retroreflectivity, decreases with increasing angles to such tangent to the road. This decrease is such that, as a car moves down a roadway ac night, for example, the driver has each individual road side refleccor in view (as respects retroreflected light) only through a maximum angle typically not greater than about 30. For the rest of the time interval that the driver is before and approaching an individual reflector (which thus covers an angular range or zone of from about 30 to ~0), the driver ~5 is unable to see the individual reflector by retroreflected light because such reflector is not retroreflective of the car headlights in that zone. Perhaps the driver can physically see an individual such reflector, but once the driver is beyond 30, and in the range of from 30 to 90, he can not see or receive any recroreflected light signal therefrom.
This limitation on retroreflective viewability causes serious night-time motorist hazards especially on curved roads since a driver is unable to see a curve ahead, or a significant distance along a curve ahead, as he proceeds tO drive along a road. What occurs is chat the driver's line or sight as he proceeds to drive along the road enters the non-reflected zone in a very brief distance since the tangent to the curve in the road curve inherently has a continuously greater angle with increases in road curvature.
Therefore, as the driver proceeds along a roadway which has an increasing degree of curvature with distance along the road, the driver has increasingly less delineation of the highway ahead owing S to the inherent limitations of such prior art retroreflectors used for road edge delineation. This limitation is most particularly evident on exit and entrance ramJps of limited access roads which ramps are extremely curved in relation to the normal road pathway connected with such a ramp.
For example, in a modern cloverleaf road interchange, where a main highway may over-cross an intersecting road via an over-pass, the intersecting road is connected with the main road through a system of connecting roads caLled a cloverleaf. Thus, at the overpass, the main highway employs a bridge-type construction.
Normally, on such a bridge-eype constmction, the median portion between the two opposing directions of traffic on the main highway is an upright construction or supporting structure presenting a potentially dangerous hazard to a car which is entering the ~ in highway from the intersecting r~ad via one of the cloverleaf entrance roads. By nature of the shape of the individual cloverleaf road ramps, an entering car approaches the hazardous median at an angle which typically may be between 45 and 7û. When delineaeed by such prior art reflector devices, the median reflectors are visible in advance to drivers proceeding in either direction along the r~ain 2S highway, but the median is not visible to the drivers apprcaching and entering into the main roadway from a cloverleaf road ramp, since, to such entering drivers, the angle of viewing of the median reflectors is beyond the retroreflectivity characteristics and capabilities of the median reflectors.
For another example, a similar situation exists with respect to cars exiting from such a main highway onto such a cloverleaf road ramp so as to enter upon such an intersecting road. In this case, the degree of curvature of the cloverleaf road ramp is so great that the prior art reflec~ors, when duly mounted so that the peak of retroreflectivity is parallel to the tangent to the curve of the road ramp, have a retroreflective viewing angle which increases rapidly with the curvature of the road and cherefore permits a driver entering or on a road ramp to see simultaneously only a very limited number of such prior art reflectors for delineating the curve ahead since the driver's line of sight is beyond the zone of retroreflectivity associated with iDdividual reflectors spaced and mounted along the roadway edge of the ramp.
From such examples, it is seen that there is a need for an improved roadside reflector system which will permit the drivers of vehicles ~o see individual roadside reflectors for a considerable distance along a road ahead. Such re~oreflec~ive viewability requires individual re~lectors each of whose retroreflectivity characteristics extend frorn about 0 up to at least about 60 and these refLectors are then stationed at desired intervals along road side edge portions.
So far as is known, nothing in the prior art in any way teaches or suggests roadway edge marking reflector systems adapted to provide appreciable, or practically sufficient, retroreflectivity beyond about 30 so that the zone of from 30 to 60 is actually completely uncovered by prior art roadside reflector systems. As indicated, between about 30 and 40, some retroreflectivity is provided by glass beaded reflectors (for example, a glass beaded sheet the so-called 'Scotch-Light" (trademark) type available from Minnesota Mining & Manufacturing Company, St.
Paul, Minnesota), but the 10 wide zone from 30 to 40 is found to be only weakly retroreflective for such glass beaded sheeting so that the viewability and the retroreflectivity characteristics of glass beaded sheeting is generally considered by those skilled in the art of highway marking to be insufficient for adequate highway safety practices at these angles of from 30 to 40. Currently, glass beaded reflectors are accepted as a 0 to about 25 material, and very little use is made of the retroreflectivi~y characteristics of glass beads in the range of from about 25 to 40 because of this inherent weakness. Thus, no known roads have ever been equipped with reflector constructions at spaced intervals along roadside edge portions such that individual reflectors provided vehicle drivers moving aLong the road with continuous reflectivity, from individual reflectors ranging at least from 0 to 60.
Consequently, there is a great need in the field of road safety for a barrier marker system in which individual reflec~ors re~roreflect through angles of from at least about 0 to at least about 60 and preferably from abcut minus 5 to plus 75 relating tO a road in order to cover the various approach angles inherently associated with vehicular operation along roadways at night time.
While, as indicated, no known individual reflector constructions adapted for this class of application have continuous retrorefLective viewability characteristics over such ranges (relative to a road), cube corner type retroreflector constructions having retroreflective continuous viewability characteristics over a range of from about 0 to 70 (measured in the same relative direction as that herein used in reference to the present class of application) have heretofore been known tO the prior art, but have been employed in, and developed for, other fields of application. For examples, see Heenan et al U.S.P. 3,887,268, Heenan et al U.S.P. 3,541,606; Golden et al U. S. P. 3,887,268; Nagel U. S. P. 3,893,747; Nagel U. S. P. 3,894, 786;
Golden et al U.S.P. 3,894,790; Nagel U.S.P. 3,895,855; Nagel U.S.P.
3,905,680; Nagel U.S. P. 3,905,681; and the Like. Commonly even when prior reflectors have retroreflective capability through included angles greater -30 such are not adapted for use in the highway marking field. For one thing, such prior art reflectors could have reflective characteristics which go so far beyond an included angle of 90 that they become safety hazards in that they could equally guide motorists approaching the same point from opposed directions.
Observe also that, for example, even if one endeavours to move a reflector of the type shown in Heenan U,S. P. 3,332,327 to an elevated position along the side of a road, one still does not obtain continuous retroreflectivity from such a reflector through an angle of from 0 to 60. In the highway barrier marker field, reflector constructions specially adapted for positloning and mounting along road side edge portions are needed and necessary in order to permit economical installation, low maintenance costs, Long life, good reflectance characteris;ics over the ranges desired (as above indicated), and the like. New and improved reflector constructions which are i ~ 4 specially adapted for this class of application are thus needed.
More specifically, in one aspect the present invention rel~tes to a roadway construction of the conventional type having generally longitudinally extending road surface portions with road side edge portions. Sometimes? markers, barriers, or equivalent impediments are located alongside of the longitudinally extending portions. Such a roadway, in accord with one aspect of the present invention, is equipped with a plurality of road edge reflector means which are each adapted to be continuously visible to drivers of vehicles moving along the road chrough an angLe of from about 0 to at least about 60 but less than about 90.
Each one of these individ~al retroreflective reflector means utilized has at least two regions thereof which are each retroreflective of incident light. Each such region has at least one flattened exterior surface portion which is inclined angularly relative to the other thereof. Each region is colored white, red, amber or blue.
A Iso, together these regions are interrelated so that they are continuously retroreflective of incident light rays striking its such two regions over a predeterminable included angLe which is at
Heretofore, in order to mark or delineate for visibility at night time by vehicle drivers road side edge portions (or road side edge barriers, or road median strips delineating the space interval between tWO ad~acent highway surfaces running parallelly to one another, or curved exit or entrance ramps associaced with so~alled super highways and other roadways, or tunnels, or bridge structures, or any hazardous object along a road), it has been conventional to employ vertically oriented reflectors. In general, three types of prior art reflectors have been employed for this class of application: (1) the prismatic triple mirror type reflector using a plurality of standard reflex type units where-in the individual cube axes are perpendicular to the suxface of the reflector; (2) the glass bead-type reflector sheeting wherein glass beads are embedded thereinto; and (3) the prismatic triple mirror type reflector using a plurality of angled cube corner-type retroreflective units (such as a reflector adapted from the teachings of Heenan [l.S.Patent 3,332,327) which is normally mounted horizontally on the pavement as a center line marker or the like, but which in this application is mounted vertically and which here employs only the front ramp-like surface of such reflector body). In this class of application, the performance of all three of these reflectors is sim.ilar to one another in that the peak of retroreflectivity of each type in terrns of light intensity when such is so mounted upon a road side edge or the like in a vertical orientation is parallel to a tangent to the road at that point. Retroreflectivity extends from chat parallel position ~sometimes termed 0), or from such a peak intensity location, -1 - , ~
through typically angles up to about 25 to 30 into the roadway, although the glass bead-type reflector sheecing appears to have slightly more angular range than this, going up to perhaps about 4oo.
S In all known such prior art types of reflectors adapted for this class of application, the reflected light output, or performance of retroreflectivity, decreases with increasing angles to such tangent to the road. This decrease is such that, as a car moves down a roadway ac night, for example, the driver has each individual road side refleccor in view (as respects retroreflected light) only through a maximum angle typically not greater than about 30. For the rest of the time interval that the driver is before and approaching an individual reflector (which thus covers an angular range or zone of from about 30 to ~0), the driver ~5 is unable to see the individual reflector by retroreflected light because such reflector is not retroreflective of the car headlights in that zone. Perhaps the driver can physically see an individual such reflector, but once the driver is beyond 30, and in the range of from 30 to 90, he can not see or receive any recroreflected light signal therefrom.
This limitation on retroreflective viewability causes serious night-time motorist hazards especially on curved roads since a driver is unable to see a curve ahead, or a significant distance along a curve ahead, as he proceeds tO drive along a road. What occurs is chat the driver's line or sight as he proceeds to drive along the road enters the non-reflected zone in a very brief distance since the tangent to the curve in the road curve inherently has a continuously greater angle with increases in road curvature.
Therefore, as the driver proceeds along a roadway which has an increasing degree of curvature with distance along the road, the driver has increasingly less delineation of the highway ahead owing S to the inherent limitations of such prior art retroreflectors used for road edge delineation. This limitation is most particularly evident on exit and entrance ramJps of limited access roads which ramps are extremely curved in relation to the normal road pathway connected with such a ramp.
For example, in a modern cloverleaf road interchange, where a main highway may over-cross an intersecting road via an over-pass, the intersecting road is connected with the main road through a system of connecting roads caLled a cloverleaf. Thus, at the overpass, the main highway employs a bridge-type construction.
Normally, on such a bridge-eype constmction, the median portion between the two opposing directions of traffic on the main highway is an upright construction or supporting structure presenting a potentially dangerous hazard to a car which is entering the ~ in highway from the intersecting r~ad via one of the cloverleaf entrance roads. By nature of the shape of the individual cloverleaf road ramps, an entering car approaches the hazardous median at an angle which typically may be between 45 and 7û. When delineaeed by such prior art reflector devices, the median reflectors are visible in advance to drivers proceeding in either direction along the r~ain 2S highway, but the median is not visible to the drivers apprcaching and entering into the main roadway from a cloverleaf road ramp, since, to such entering drivers, the angle of viewing of the median reflectors is beyond the retroreflectivity characteristics and capabilities of the median reflectors.
For another example, a similar situation exists with respect to cars exiting from such a main highway onto such a cloverleaf road ramp so as to enter upon such an intersecting road. In this case, the degree of curvature of the cloverleaf road ramp is so great that the prior art reflec~ors, when duly mounted so that the peak of retroreflectivity is parallel to the tangent to the curve of the road ramp, have a retroreflective viewing angle which increases rapidly with the curvature of the road and cherefore permits a driver entering or on a road ramp to see simultaneously only a very limited number of such prior art reflectors for delineating the curve ahead since the driver's line of sight is beyond the zone of retroreflectivity associated with iDdividual reflectors spaced and mounted along the roadway edge of the ramp.
From such examples, it is seen that there is a need for an improved roadside reflector system which will permit the drivers of vehicles ~o see individual roadside reflectors for a considerable distance along a road ahead. Such re~oreflec~ive viewability requires individual re~lectors each of whose retroreflectivity characteristics extend frorn about 0 up to at least about 60 and these refLectors are then stationed at desired intervals along road side edge portions.
So far as is known, nothing in the prior art in any way teaches or suggests roadway edge marking reflector systems adapted to provide appreciable, or practically sufficient, retroreflectivity beyond about 30 so that the zone of from 30 to 60 is actually completely uncovered by prior art roadside reflector systems. As indicated, between about 30 and 40, some retroreflectivity is provided by glass beaded reflectors (for example, a glass beaded sheet the so-called 'Scotch-Light" (trademark) type available from Minnesota Mining & Manufacturing Company, St.
Paul, Minnesota), but the 10 wide zone from 30 to 40 is found to be only weakly retroreflective for such glass beaded sheeting so that the viewability and the retroreflectivity characteristics of glass beaded sheeting is generally considered by those skilled in the art of highway marking to be insufficient for adequate highway safety practices at these angles of from 30 to 40. Currently, glass beaded reflectors are accepted as a 0 to about 25 material, and very little use is made of the retroreflectivi~y characteristics of glass beads in the range of from about 25 to 40 because of this inherent weakness. Thus, no known roads have ever been equipped with reflector constructions at spaced intervals along roadside edge portions such that individual reflectors provided vehicle drivers moving aLong the road with continuous reflectivity, from individual reflectors ranging at least from 0 to 60.
Consequently, there is a great need in the field of road safety for a barrier marker system in which individual reflec~ors re~roreflect through angles of from at least about 0 to at least about 60 and preferably from abcut minus 5 to plus 75 relating tO a road in order to cover the various approach angles inherently associated with vehicular operation along roadways at night time.
While, as indicated, no known individual reflector constructions adapted for this class of application have continuous retrorefLective viewability characteristics over such ranges (relative to a road), cube corner type retroreflector constructions having retroreflective continuous viewability characteristics over a range of from about 0 to 70 (measured in the same relative direction as that herein used in reference to the present class of application) have heretofore been known tO the prior art, but have been employed in, and developed for, other fields of application. For examples, see Heenan et al U.S.P. 3,887,268, Heenan et al U.S.P. 3,541,606; Golden et al U. S. P. 3,887,268; Nagel U. S. P. 3,893,747; Nagel U. S. P. 3,894, 786;
Golden et al U.S.P. 3,894,790; Nagel U.S.P. 3,895,855; Nagel U.S.P.
3,905,680; Nagel U.S. P. 3,905,681; and the Like. Commonly even when prior reflectors have retroreflective capability through included angles greater -30 such are not adapted for use in the highway marking field. For one thing, such prior art reflectors could have reflective characteristics which go so far beyond an included angle of 90 that they become safety hazards in that they could equally guide motorists approaching the same point from opposed directions.
Observe also that, for example, even if one endeavours to move a reflector of the type shown in Heenan U,S. P. 3,332,327 to an elevated position along the side of a road, one still does not obtain continuous retroreflectivity from such a reflector through an angle of from 0 to 60. In the highway barrier marker field, reflector constructions specially adapted for positloning and mounting along road side edge portions are needed and necessary in order to permit economical installation, low maintenance costs, Long life, good reflectance characteris;ics over the ranges desired (as above indicated), and the like. New and improved reflector constructions which are i ~ 4 specially adapted for this class of application are thus needed.
More specifically, in one aspect the present invention rel~tes to a roadway construction of the conventional type having generally longitudinally extending road surface portions with road side edge portions. Sometimes? markers, barriers, or equivalent impediments are located alongside of the longitudinally extending portions. Such a roadway, in accord with one aspect of the present invention, is equipped with a plurality of road edge reflector means which are each adapted to be continuously visible to drivers of vehicles moving along the road chrough an angLe of from about 0 to at least about 60 but less than about 90.
Each one of these individ~al retroreflective reflector means utilized has at least two regions thereof which are each retroreflective of incident light. Each such region has at least one flattened exterior surface portion which is inclined angularly relative to the other thereof. Each region is colored white, red, amber or blue.
A Iso, together these regions are interrelated so that they are continuously retroreflective of incident light rays striking its such two regions over a predeterminable included angLe which is at
2~ least about 6~ but less than about ~0 measured outwardly from one such flattened e~terior surface portion. ~uch retroreflected light from each of such reflector means at any given Location within such included angle has a minimum specific intensity value for retroreflectivity which is at least tha~ shown in the following Table:
1 (for reasons of adequate viewability when such reflector means is installed along a roadway):
TA BLE
Color of such one re~ion_ Specific intensity value in candelas per foot candle White 20 Red 5 A mber 12 Blue 5 In another aspect, the present invention relates to an im-proved reflector means of the cube-corner type which when suitably mounted along a roadside edge is adapted to be continuously - visible by retroreflected light to drivers of vehicles moving alongthe road at night-time through a viewing angle of from about 0 to at least about 60, but always leæs than about 90. Such reflector means utilizes two retroreflective regions. Each such region has a flattened exterior surface portion which is inclined angularly relative to the other thereof, and each such region is typically, though not necessarilyJ colored white, red, amber or blue.
These two regions are interrelated in that they coact to continuously retroreflect incident light rays striking same over a predeterminable included angle which is at least about 60 but less than about 90 prefe~ably measured outwardly from one such fla~tened exterior surface portion. Retrorefle~ted light from such refle~tor means so colored at any given location within such included angle of about 60 to 90 preferably has a minimum specific incensity value for retroreflectivity which is at least that shown in the above Table 1.
In addition, the invencion employs a plurality of mounting means.
Each individual mounting means is associated with a different iL~ 4 respective one of the indicated reflector means. Each such mount-ing means holds its associated such respective reflector means in a predetermined orientation and in a predetermined region relative to such roadway construction that the following relationships are maintained:
1. Such one flattened surface portion is generally vertic~l;
2. Such one flat~ened surface portion is so positioned to the road side edge portions or to longitudinally extending road surface portions that, in relation to an included angle of 60, 0 thereof extends substantially parallelly to a tangent to one of said road side edge portions (or to longitudinally extending road surface portions, as the case may ~e) in such region where each respective one of such reflector means is positioned. In a system of this invention, individual ones of such reflector means are in longitudinally spaced relationship relative to one another longitudinally along such roadway construction; and each respective one of such reflector means of such plu~ality thereof is Located relative to such roadway construction in a similar spatial position Preferably, and typically such individual reflector means are located in spaced relationship to the surface pordons of a given roadway construction with median heights above road surface portions of from about 6 inches to 60 inches being typical.
The interrelationship berween such a plurality of reflector means and such road surface portions ~s such that the driver of a vehiclP moving along such road surface portions a~ night-time, such being equipped with headlight means, can continuously see each individual reflector means within a viewing angle of from about 0 ''4 to at leas~ about 60, ~ut less that 90, where 0 extends substantially parallelly to a tangent to one of said roadside portions in the region where such reflector means is mounted and where 60 and 90 extends outwardly into such road surface portions from such a tangent. Preferably, such continuous individualy reflector vision extends from about -5 to 75.
An object of the present invention is to provide a new and improved safety system for highway barrier marking which utilizes reflectors that can be continuously seen individually not only through angles of from about 0 to 25 or 30, as in the prior art, but which can also be continuously seen at angles from about 25 or 30 up to at least about 60, and which can preferably be seen continuously at angles of from about -5 to 75, but less than about 90.
A further object of this invention is to provide improved reflector constructions and arrangements particularly well suited for use in the practice of the improved safety system of the present invention.
A further object is to provide an improved reflector system which creates better (relative to prior art) road delineation characteristics for both straight and curved vehicular roads, such system being particularly well adapted for use with highway systems of the so-called modern super highway type having roadside barriers, and the like.
A further obJect of this invention is to provide a system of the class indicated a~ove which is simple, efficient, reLiab~e, economical, and Long lasting which useS reflectors that are adapted for use with existing and availabae roadside mounting means.
A further object is to provide an improved barrier marker reflector means which provides superior (relative to prior art) road delineation characteristics for both straight and curved vehicular roads, such reflector means being particu-larly well adapted for use with highway systems of the so-called modern super highway type having roadside barriers.
Another object of this invention is to provide a re-flector means of the class indicated above which is simple, efficient, reliable, economical, and long lasting, and which is relatively flat.
Thus, in accordance with a broad aspect of the in-vention, there is provided a reflector for improved roadside barrier marking comprising (A) a backing member of integral, one piece, rigid construction having -- (1) a base flattened portion (2) an upstanding flattened leg portion along one edge of said base portion which is inclined in relation to said base portion at an angle ranging from about 60 to 85 (B) two molded transparent flattened bodies, each having a flattened outerface and an inner face with a plurality of cube corner type retro-reflective units formed thereinto and further having an inturnedperipheral shoulder which extends beyond its associated inner face, (1) one of said flattened bodies being larger than the other thereof and being adapted to fit against the inside face o said base portion with the edge portions of said shoulder thereof engaged thereagainst, (2) said other flattened body being adapted to fit against the inside face of said leg portion with the edge portions of said shoulder thereof engaged thereagainst, and (C) bonding means adhering such respective shoulder edge portions to said backing member at such locations of engagement, (D) said flattened bodies in combination with said backing member being adapted to retroreflect incident light rays striking said outer faces thereof within an angle ~, ,`,~'t~
11 ~ ~jb,~;~4 of about 60 where 0 is taken along a hypothetical line which is generally parallel to the outer face of said one flattened body and which is generally perpendicular to the outer face of : said other flattened body and where 60 is measured vertically upwards, from said 0 line and outwardly from the outer face of said one flattened body.
Other and further objects, aims, purposes, features, advantages, modes, applications, variations, and the like will be apparent to those skilled in the art from the teachings of the present specification taken tcgether with the drawings.
IN THE DRAWI NGS
. _ _ Figure 1 is a diagrammatic partial view of a road equipped with prior art type road side barrier markers illustra-ting the type of pattern of retroreflected light from such markers seen by vehicle drivers traversing such road in the night time;
E'igure 2 is a transverse sectional view taken through a mid-region of a prior art barrier marker embodiment;
Figure 3 is a view similar to Figure 1 but showing another such road equipped with road side barrier markers of the present invention;
Figure 4 is a perspective view of one embodiment of a road side barrier marker of the present invention;
Figure 5 is an end elevational view of the barrier marker embodiment shown in Figure 4, showing such embodiment mounted ~^ -lla-upon a surface;
Figure 6 is a transverse sectional view taken through a mid region of the barrier marker em~odiment shown in Figure 4;
Figure 7 is an enlarged fragmentary sectional view taken through the region VII-VII of Figure 6;
Figure 8 is a plot in rectangular coordinates illustrating the manner in which light is retroreflected from respeccive ones of the reflector^equipped surfaces utilized in the barrier marker embodiment of Figure 4;
Fi~re 9 is a sectional view similar to Figure 6 but showing an alternative embodiment of a barrier marker of the present invention;
Figure 10 is an elevational view similar to Figure 5 but illustrating the embodiment shown in Figure 9;
Figure 11 îs a partial seetional view similar to Figure 6 but showing a further alternative embodiment of a barrier marker of the present invention;
Figure 12 is a sectional view similar to Fig. 6 but illustrating a still further embodiment of a barrier marker of ~he presen~ invention;
Figure 13 is a fragmentary elevational view of the embodiment of Fig. 12 showing the mouncing means used in such embodimen t;
Figure 14 is a plan view of a barrier marker embodiment usable in the practice of the present invention which emplays recroreflective glass beaded sheeting;
i~ 3~i~34 Figure 15 is a front elevational view of dle embodiment shown in Fig. 14;
Figure 16 is a plot in rectangular coordinates showing the characteristic relationships between specific intensity in candela S per foot candle versus viewing angle at various viewing angles for two different respective barrier markers, one thereof being of the p rio r a rt;
Figure 17 is a diagrammatic plan view of an actual embodiment of the present invention;
Figure 18 is a sectional view similar to Fig. 6 but showing an alterna~ive embodimenc of a barrier marker of the present invention;
and Figure 19 is a sectional view similar to Fig. 6 but showing an alternative embodiment of a barrier marker of the present invendon.
Figure 20 is a perspective view of another embodiment of a reflector assembly of the present invention illustrating another alternative mounting means therefor;
Figure 21 is a vertical sectional view taken ~hrough a roadway guard rail having mounted thereto an embodiment of Figure 8;
Figure 22 is a front elevational view of the embodiment of Fi gu re 8; and Pigure 23 is a fragmentary view of another embodiment of a reflector assembly useful in this invention illustrating ano~her alternative mounting means ~hereor.
Referring ~o Figure 1, there is seen, for present illustrative purposes, a fragment of a modern di~rided highway construction 20, ``` -11~3~4 sometimes referred to as a super highway, comprised of four paved lanes 21, 22, 23, and 24. Lanes 21 and 22 accommodate vehicular traffic moving in this drawing to the left, as indicated by the car and arrow 25, while lanes 23 and 24 accommodate vehicular traffic moving to the right as illustrated by the car and arrow 26. The lanes 21 and 22 are separated from the lanes 23 and 24 by an up-standing concrete barrier wall 27 (or the like) which extends long-itudinaLly between the lanes 22 and 23. Dotted line 35 here delineates contiguous lanes 21 and 22 and doc~ed lines 36 here delineates contiguous lanes 23 and 24. On the outside of the lane 21~ a shoulder 28 (paved) is provided, and on the outside of lane 24 a shoulder 29 (paved) is provided. Highway 20 is of the type designed for limited vehicular access. The portion of highway 20 shown includes a fragment of an exit ramp 30 of a so-called scissors type upon which exiting traffic may leave highway 20 without stopping from lane 21 while decelerating. The movement of traffic along exit ramp 30 is designated by the illustrative car and arrow 38. Ramp 30 is here comprised of one lane 32 with an adjacent contiguous shoulder 31; road edge 37 separates these regions in Fig. I. Areas 33 and 34 are provided along opposing side edge portions of road 30 and in these areas barrier markers are provided.
Highway 20 and ramp 30 are each provided and e~uipped with prior art type longitudinally spaced (relative to highway 20 and ramp 30) reflectorized barrier or road edge rnarkers which are each for convenience herein designated by the numeral 40. ~he reflectors 40 are located along roadside edge portions~ Thus, the reflectors 40 ar~ Located ir~- longi~udinally spaced relationships to one another along the edge portions of the respective shoulders 28 and 29 and 33 and 34. In addition, opposed side wall portions of the barrier wall 27 are provided at longitudinally spaced intervals with reflectors 40 (see Fig. 2).
Such a prior art reflector 40 is adapted to retroreflect light only through a maximum angle typically not greater than about 30.
The included angle of recroreflectivity for each reflector 40 is so arranged tby orienting each reflector 40 relative to highway 20 and ramp 30) that retroreflectivity extends generally from a position parallel to a tangent to the road edge at the location of an individual reflector 40 out into the roadway at an angle of about 25 to 30 maximum. Each of the reflectors 40 illustrated in Figure I along the highway 20 and the ramp 30 is provided with a pair of intersecting broken lines to illustrate an included 30 angle through which light is retroreflected as respects incident rays striking retroreflective portions of an individual reflector 40. As can be seen, the driver of each of the vehicles 2S, 26, and 38 is able to view each individual roadside reflector 40 (as respects retroreflected light) only through a maximum angle typically not greater than about 30, from a tangent to the roadway at the mounting portion of the reflector. For the rest of the time interval that each respective such driver of vehicles 25, 26 and 31 is before and approaching an individual reflector 40 (which time interval thus covers an angular range or zone of from about 30 to 90 relative to each individual reflector 40), the driver of the individual vehicles 25, 26 and 31 is unable to see the individual reflectors 40 by retroreflected light because such individual
1 (for reasons of adequate viewability when such reflector means is installed along a roadway):
TA BLE
Color of such one re~ion_ Specific intensity value in candelas per foot candle White 20 Red 5 A mber 12 Blue 5 In another aspect, the present invention relates to an im-proved reflector means of the cube-corner type which when suitably mounted along a roadside edge is adapted to be continuously - visible by retroreflected light to drivers of vehicles moving alongthe road at night-time through a viewing angle of from about 0 to at least about 60, but always leæs than about 90. Such reflector means utilizes two retroreflective regions. Each such region has a flattened exterior surface portion which is inclined angularly relative to the other thereof, and each such region is typically, though not necessarilyJ colored white, red, amber or blue.
These two regions are interrelated in that they coact to continuously retroreflect incident light rays striking same over a predeterminable included angle which is at least about 60 but less than about 90 prefe~ably measured outwardly from one such fla~tened exterior surface portion. Retrorefle~ted light from such refle~tor means so colored at any given location within such included angle of about 60 to 90 preferably has a minimum specific incensity value for retroreflectivity which is at least that shown in the above Table 1.
In addition, the invencion employs a plurality of mounting means.
Each individual mounting means is associated with a different iL~ 4 respective one of the indicated reflector means. Each such mount-ing means holds its associated such respective reflector means in a predetermined orientation and in a predetermined region relative to such roadway construction that the following relationships are maintained:
1. Such one flattened surface portion is generally vertic~l;
2. Such one flat~ened surface portion is so positioned to the road side edge portions or to longitudinally extending road surface portions that, in relation to an included angle of 60, 0 thereof extends substantially parallelly to a tangent to one of said road side edge portions (or to longitudinally extending road surface portions, as the case may ~e) in such region where each respective one of such reflector means is positioned. In a system of this invention, individual ones of such reflector means are in longitudinally spaced relationship relative to one another longitudinally along such roadway construction; and each respective one of such reflector means of such plu~ality thereof is Located relative to such roadway construction in a similar spatial position Preferably, and typically such individual reflector means are located in spaced relationship to the surface pordons of a given roadway construction with median heights above road surface portions of from about 6 inches to 60 inches being typical.
The interrelationship berween such a plurality of reflector means and such road surface portions ~s such that the driver of a vehiclP moving along such road surface portions a~ night-time, such being equipped with headlight means, can continuously see each individual reflector means within a viewing angle of from about 0 ''4 to at leas~ about 60, ~ut less that 90, where 0 extends substantially parallelly to a tangent to one of said roadside portions in the region where such reflector means is mounted and where 60 and 90 extends outwardly into such road surface portions from such a tangent. Preferably, such continuous individualy reflector vision extends from about -5 to 75.
An object of the present invention is to provide a new and improved safety system for highway barrier marking which utilizes reflectors that can be continuously seen individually not only through angles of from about 0 to 25 or 30, as in the prior art, but which can also be continuously seen at angles from about 25 or 30 up to at least about 60, and which can preferably be seen continuously at angles of from about -5 to 75, but less than about 90.
A further object of this invention is to provide improved reflector constructions and arrangements particularly well suited for use in the practice of the improved safety system of the present invention.
A further object is to provide an improved reflector system which creates better (relative to prior art) road delineation characteristics for both straight and curved vehicular roads, such system being particularly well adapted for use with highway systems of the so-called modern super highway type having roadside barriers, and the like.
A further obJect of this invention is to provide a system of the class indicated a~ove which is simple, efficient, reLiab~e, economical, and Long lasting which useS reflectors that are adapted for use with existing and availabae roadside mounting means.
A further object is to provide an improved barrier marker reflector means which provides superior (relative to prior art) road delineation characteristics for both straight and curved vehicular roads, such reflector means being particu-larly well adapted for use with highway systems of the so-called modern super highway type having roadside barriers.
Another object of this invention is to provide a re-flector means of the class indicated above which is simple, efficient, reliable, economical, and long lasting, and which is relatively flat.
Thus, in accordance with a broad aspect of the in-vention, there is provided a reflector for improved roadside barrier marking comprising (A) a backing member of integral, one piece, rigid construction having -- (1) a base flattened portion (2) an upstanding flattened leg portion along one edge of said base portion which is inclined in relation to said base portion at an angle ranging from about 60 to 85 (B) two molded transparent flattened bodies, each having a flattened outerface and an inner face with a plurality of cube corner type retro-reflective units formed thereinto and further having an inturnedperipheral shoulder which extends beyond its associated inner face, (1) one of said flattened bodies being larger than the other thereof and being adapted to fit against the inside face o said base portion with the edge portions of said shoulder thereof engaged thereagainst, (2) said other flattened body being adapted to fit against the inside face of said leg portion with the edge portions of said shoulder thereof engaged thereagainst, and (C) bonding means adhering such respective shoulder edge portions to said backing member at such locations of engagement, (D) said flattened bodies in combination with said backing member being adapted to retroreflect incident light rays striking said outer faces thereof within an angle ~, ,`,~'t~
11 ~ ~jb,~;~4 of about 60 where 0 is taken along a hypothetical line which is generally parallel to the outer face of said one flattened body and which is generally perpendicular to the outer face of : said other flattened body and where 60 is measured vertically upwards, from said 0 line and outwardly from the outer face of said one flattened body.
Other and further objects, aims, purposes, features, advantages, modes, applications, variations, and the like will be apparent to those skilled in the art from the teachings of the present specification taken tcgether with the drawings.
IN THE DRAWI NGS
. _ _ Figure 1 is a diagrammatic partial view of a road equipped with prior art type road side barrier markers illustra-ting the type of pattern of retroreflected light from such markers seen by vehicle drivers traversing such road in the night time;
E'igure 2 is a transverse sectional view taken through a mid-region of a prior art barrier marker embodiment;
Figure 3 is a view similar to Figure 1 but showing another such road equipped with road side barrier markers of the present invention;
Figure 4 is a perspective view of one embodiment of a road side barrier marker of the present invention;
Figure 5 is an end elevational view of the barrier marker embodiment shown in Figure 4, showing such embodiment mounted ~^ -lla-upon a surface;
Figure 6 is a transverse sectional view taken through a mid region of the barrier marker em~odiment shown in Figure 4;
Figure 7 is an enlarged fragmentary sectional view taken through the region VII-VII of Figure 6;
Figure 8 is a plot in rectangular coordinates illustrating the manner in which light is retroreflected from respeccive ones of the reflector^equipped surfaces utilized in the barrier marker embodiment of Figure 4;
Fi~re 9 is a sectional view similar to Figure 6 but showing an alternative embodiment of a barrier marker of the present invention;
Figure 10 is an elevational view similar to Figure 5 but illustrating the embodiment shown in Figure 9;
Figure 11 îs a partial seetional view similar to Figure 6 but showing a further alternative embodiment of a barrier marker of the present invention;
Figure 12 is a sectional view similar to Fig. 6 but illustrating a still further embodiment of a barrier marker of ~he presen~ invention;
Figure 13 is a fragmentary elevational view of the embodiment of Fig. 12 showing the mouncing means used in such embodimen t;
Figure 14 is a plan view of a barrier marker embodiment usable in the practice of the present invention which emplays recroreflective glass beaded sheeting;
i~ 3~i~34 Figure 15 is a front elevational view of dle embodiment shown in Fig. 14;
Figure 16 is a plot in rectangular coordinates showing the characteristic relationships between specific intensity in candela S per foot candle versus viewing angle at various viewing angles for two different respective barrier markers, one thereof being of the p rio r a rt;
Figure 17 is a diagrammatic plan view of an actual embodiment of the present invention;
Figure 18 is a sectional view similar to Fig. 6 but showing an alterna~ive embodimenc of a barrier marker of the present invention;
and Figure 19 is a sectional view similar to Fig. 6 but showing an alternative embodiment of a barrier marker of the present invendon.
Figure 20 is a perspective view of another embodiment of a reflector assembly of the present invention illustrating another alternative mounting means therefor;
Figure 21 is a vertical sectional view taken ~hrough a roadway guard rail having mounted thereto an embodiment of Figure 8;
Figure 22 is a front elevational view of the embodiment of Fi gu re 8; and Pigure 23 is a fragmentary view of another embodiment of a reflector assembly useful in this invention illustrating ano~her alternative mounting means ~hereor.
Referring ~o Figure 1, there is seen, for present illustrative purposes, a fragment of a modern di~rided highway construction 20, ``` -11~3~4 sometimes referred to as a super highway, comprised of four paved lanes 21, 22, 23, and 24. Lanes 21 and 22 accommodate vehicular traffic moving in this drawing to the left, as indicated by the car and arrow 25, while lanes 23 and 24 accommodate vehicular traffic moving to the right as illustrated by the car and arrow 26. The lanes 21 and 22 are separated from the lanes 23 and 24 by an up-standing concrete barrier wall 27 (or the like) which extends long-itudinaLly between the lanes 22 and 23. Dotted line 35 here delineates contiguous lanes 21 and 22 and doc~ed lines 36 here delineates contiguous lanes 23 and 24. On the outside of the lane 21~ a shoulder 28 (paved) is provided, and on the outside of lane 24 a shoulder 29 (paved) is provided. Highway 20 is of the type designed for limited vehicular access. The portion of highway 20 shown includes a fragment of an exit ramp 30 of a so-called scissors type upon which exiting traffic may leave highway 20 without stopping from lane 21 while decelerating. The movement of traffic along exit ramp 30 is designated by the illustrative car and arrow 38. Ramp 30 is here comprised of one lane 32 with an adjacent contiguous shoulder 31; road edge 37 separates these regions in Fig. I. Areas 33 and 34 are provided along opposing side edge portions of road 30 and in these areas barrier markers are provided.
Highway 20 and ramp 30 are each provided and e~uipped with prior art type longitudinally spaced (relative to highway 20 and ramp 30) reflectorized barrier or road edge rnarkers which are each for convenience herein designated by the numeral 40. ~he reflectors 40 are located along roadside edge portions~ Thus, the reflectors 40 ar~ Located ir~- longi~udinally spaced relationships to one another along the edge portions of the respective shoulders 28 and 29 and 33 and 34. In addition, opposed side wall portions of the barrier wall 27 are provided at longitudinally spaced intervals with reflectors 40 (see Fig. 2).
Such a prior art reflector 40 is adapted to retroreflect light only through a maximum angle typically not greater than about 30.
The included angle of recroreflectivity for each reflector 40 is so arranged tby orienting each reflector 40 relative to highway 20 and ramp 30) that retroreflectivity extends generally from a position parallel to a tangent to the road edge at the location of an individual reflector 40 out into the roadway at an angle of about 25 to 30 maximum. Each of the reflectors 40 illustrated in Figure I along the highway 20 and the ramp 30 is provided with a pair of intersecting broken lines to illustrate an included 30 angle through which light is retroreflected as respects incident rays striking retroreflective portions of an individual reflector 40. As can be seen, the driver of each of the vehicles 2S, 26, and 38 is able to view each individual roadside reflector 40 (as respects retroreflected light) only through a maximum angle typically not greater than about 30, from a tangent to the roadway at the mounting portion of the reflector. For the rest of the time interval that each respective such driver of vehicles 25, 26 and 31 is before and approaching an individual reflector 40 (which time interval thus covers an angular range or zone of from about 30 to 90 relative to each individual reflector 40), the driver of the individual vehicles 25, 26 and 31 is unable to see the individual reflectors 40 by retroreflected light because such individual
3~i~4 reflectors 40 are not retroreflective of the csr headlights in that zone.
In addition, it is a further characteristic of such prior art reflectors 40 that reflected ligh~ output, or performance of retro-S reflectivity, decreases with increasing angles from 0 (or the tangent to the roadway). In other words, the amount of light that the driver of a vehicle 25, 26, or 31 sees as he moves his vehicle down a lane such as 32, 21, or 23 continuously declines from an individual retroreflector 40 as the angle of viewing of each individual reflector 40 increases towards 25 or 30 when each reflector 40 becomes invisible to a driver as respects retro-reflected light.
As a consequence of the above characteristics, a driver's field of view as he proceeds along a road equipped with prior art reflectors 40 is such that a non-reflectorized zone in this field of view is entered regularly at very brief distances and intervals along the road corresponding to individual reflectors. Thus, when a driver is proceeding down a straight road, a blinking or fluttering light pattern is produced from individual reflectors 40 when a driver is proceeding along a road, particularly along a curved roadway which has an increasing degree of curvature with increasing distance along the road. Conse~uently, a driver has increasingly less delineation of a road ahead in the curved road situation owing to the inherent limitations of suoh prior art retroreflectors. Such limitations on retroreflective viewability cause serious night time motorist hazards.
To overcome such hazards, the present invention provides a roadside barrier marker system employing cube corner type retro-reflectors which retroreflect continuously through an angle of at least about 60 ~rom 0 (located paraLlelly to a road). Re~Lectors used in the system of the present invention are so constructed, mounted and oriented relative to a given road that the driver of a vehicle moving along such road equipped with headlight means can continuously see individual reflector means within a viewing Line angle of from about 0 to 6û, where 0 extends substantially parallelly to a tangent to one of the roadside edge portions in the region where the reflector is mounted.
One exemplary embodiment of a barrier marker system of the present invention is illustrated in Figure 3 wherein is shown a modern divided highway construction which is similar to that shown in Figure 1 and described above. For reasons of convenience and brevity, similar elements in Figure 3 corresponding to those in Figure I are similarLy numbered but with the addition of prime marks thereto.
Here, highway 20' and ramp 3G' are each provided and equipped with reflectorized barrier or road edge markers which are each for convenience herein entirely designated by the numeral 60. Like the refLectors 40, the reflectors 60 are located along road side edge portions in su~stitution for the individual positions occupied by the reflectors 40.
Each reflector 60 is adapted to retroreflect Light through a max-imum angle ranging at least from about -5 ~hrough about 75. The included angle of retrore1ectivity for each reflector 60 is so arranged (by orienting each reflector 60 relative to highway 20' and ramp 30') that retrorefle~tlvity extends generalLy from a postion approximately 5 to the outside of a tangent to the road edge at the location of an individual reflector 60 out into the roadway at an angle of about 75 maximum. Each of the reflectors 60 illustrated in Figure 2 along the highway 20' and the ramp 30' is provided with a pair of intersecting broken Lines to illustrate an included angle of 80 through which light is retroreflected as respects incident rays striking retroreflective portions of an individual reflector 60. As can be seen, the driver of each of the vehicles 25', 26' and 31~ is able to view each individual road side reflector 60 (as respects retroreflected light) through a ~TIaximum angle ~rpically greater than about 80. Thus each such driver continuously is able to see by retroreflected light each individual reflector 60 during the entire time interval that the respective vehicle involved remain behind and approaching an individual reflector 60.
The candela per foot candle signal that the driver of a vehicle 25', 26' or 38' sees as he moves his vehicle down a lane such as 32', 21' or 23' remains relacively constant, particularly in the angular range between about 0 and 60.
As a consequence of the above characteristics, a driver's field of view as he proceeds along a road equipped with the reflector 60 is such that no non-reflectorized zone in this field of view is entered for an indivi~ual reflector as a vehicle such as 38', 25' or 26' moves down the road until such vehicle nears an angle of 90 with respec~ to an individual reflector 60 adjacent theret~, respectiveLy.
Thus, the limitations on retroreflective viewability associated with prior ar~ reflectors 40 is su~s~antially completely eliminated.
One exemplary embodiment of a reflector construction of the present invention is shown in Figures 4 through 7 and is designated in its entirety by the numeral 60. Reflector construction 60 is provided with a backing member 44 of integral one-piece rigid S construction. The backing member 44 has a base portion 46 which is flattened and an inclined (relative to base portion 46) leg portion 47 which is Likewise flattened. Leg portion 47 upstands at an inclined angle 55 along one edge 48 of the base portion 46. Angle 55 ranges from about 60 to 85~; and preferably from about 75 to 85. In reflector 60, angle 55 is about 80 which is presently a most preferred incLination angle. The backing member 44 is preferably comprised of a molded thermoplastic or thermosetting plastic composition, such as one comprised of ABS, nylon, polyester, or the like, but alternatively may be formed of a sheet metal, or the like, as desired.
Reflector construction 60 incorporates two molded transparent retroreflective flattened rectangularly sided bodies 49 and 51 which can be comprised of a plastic, such as an acrylic or a polycarbonate resin. Each such body 4~ and 51 has a flattened oucer face 52 and 53 respectively, as well as an inner face 54 and 56, respectively, which is generally parallel to its respective outer face 52 and S3 Each inner face 54 and S6 has formed thereinto a plurality of individual cube corrler cype retroreflective units 61 and 62, respectively. A 11 units 61 in inner face 54 are arranged so as ;o b generally coplanar relative to one another, and similarly for all the units 62 in inner face 56, respectively. An inturned peripheral shoulder 57 and 58, respecti~ely, extends about each body 49 and 51, and projec~s beyond itS respective associated inner face 54 and 56. Each such shoulder 57 and 58 preferably and as here illustrated terminates in an outturned flange 68 and 69, respectively, ~o pro-S vide a mounting surface. Preferably, both bodies 49 and 51 have the same color in an indi~,-idual reflector 60 construction. The surface area of outer face 52 is preferably from about 1. S to 3. 5 times larger than the surface area of outer face 53, though this ratio can vary greatly in practice without departing from the present invention.
Bodies 49 and ~I have their respective flanges 6~ and 69 positioned against, and mounted tO, base 46 and Leg 47 of backing member 44, respectively. Any convenient mounting means for b odies 49 and 51 may be employed, such as an adhesive, or the Iike, but here ultrasonic welding is employed preferentially and as illustrated. During assembly, body 51 is first rnounted to leg 47, and then body 49 is mounted to base 46. Flange 68 is provided with a spacing ear 71 integrally formed therewith which serves to locate and orient body 49 relative to backing member 44 and body 51 in a desired manner before ultrasonic welding (see Fig. 7).
Preferably, and as shown, integrally formed ribs 73 and 74 upstand from the opposed sides of base 46 and leg 47, respectiveLy, and integrally formed rlb 76 upstands from the forward edge of base 46. Ribs 73, 76 and 74 are joined end to end with one another integrally. Ribs 73, 74 and 76 aid in rigidifying and strengthening backing merrlber 74, and aid in protecting edge portions of bodies 49 and 51 from bumps or impacts.
The general narure and conscruction of cube corner type retroreflective units and reflectors utilizing same is well known; see, for instance, the disclosure contained in U. S. Pats. 3, 894, 786 or 3,893,747, or that in the Heenan and Nagel El.S.P. 3,541,606 and elsewhere .
In a reflector construction 60, when angle 55 is in the preferred range above indicated, the cube corner units 62 of retroreflective body 51 are preferably of the so-called standard type. Thus, the respective optical axes (not detailed) of the individual respective units 62 are preferably normal to the outer face 53 thereof, and retroreflective body Sl is then adapted to retroreflect light rays incident against face 53 through a solid cone angle 63 of up to about 25 to 30 around a perpendicular 64 to face 53, as those skilled in the art will appreciate. The cube corner retroreflective units in body 51 have optical axes which are parallel to one another and which are generally inclined at an angle of frorn about 0 to 15 with respect to a perpendicular 64 to the face 53 of body 51. Retroreflective body Sl is adapted to retroreflect light rays incident against face 53 up to about 50 relative to one side of the prependicular 64.
In order to minimize the characteristic so-called clover-leaf pattern of retroreflection associated with retroreflection from a single group of standard cube corner units which are all similarly oriented, and to make suoh pattern more uniform and circular, it is preferred, but not necessary, to divide the units 6~ into two equally sized groups, and to rotate the axes of the units of one group 180 with respect to ~he axes of the units of the other group.
As shown in Fig. 4, in retroreflective body 51, such an arrangement is used so that one gr~p 62A is formed in the inner face 56 in the upper haLf of the body 51 while a~lother group 62B is formed in the inner face 56 in the lower half of the body 51.
Also, in reflector 60, the cube corner units 61 of retro-reflective body 49 are preferably of the so-called wide angle type.
Thus, the respective optical axes, illustrated by line 59, of the individual respective units 61 are inclined at an angle 66 of from about 20 to 35 (preferably 25 to 309 with respe~t to a perpendicular 65 to outer face 52 of flattened retroreflective body 49. Thus, ligh~ rays within an included angle 94 of from about 65 to 75 to one side of perpendicular 65 to about 5 to l5 to the same side of perpendicular 65 striking face 52 are retroreflected. The orientation of angle 94 is such that the location of its greatest lateral or side projection istowards side 67 of body 49. Thus, when body 49 is mounted on base 46, as shown, for example, in Figs. 4 and 6, the orientation of body 49 is such that body 49 is retroreflective of incident light rays striking against face 52 from locacions lateral and outside of side 67 and from directions generally opposite to those from opposed locations beyond leg 47 and body 51.
If desired, each body 49 and 51 can have formed therein more than one group of cube corner retroreflective units. Each such group can have its optical axes of individual units all parallel to one another in each body 49 or 51. Ihe axes of one such group can ~e rotated wich respect to a second such group, for example, or the axes of one sslch group within the angular relationships herein above indicated, or both, if desired.
~3~6~4 Preferably a reflector such as refLector 60~ has a base portion and a leg portion which are each rectangular in perimeter configuration. A lso preferably, the leg portion has a transverse width measured from the acute angle formed between the leg portion and the base portion which is not more than about one-half the transverse width measured from such acute angle of the base portion in a reflector, such as reflector 60.
Any convenient mounting means or technique may be employed.
One technique for moun~ing a reflector 60 is to appLy over the back surface 77 of base 46, an adhesive layer 78, comprised of, for example, a butyl rubber based pressure sensitive adhesive tape~
or the like. Until the time of application, the exposed surface of layer 78 can be covered by a coated paper release sheet, or equivalent, if desired (removed and not shown). Layer 81 is an optional but not preferred adhesive cushioning layer applied between layer 78 and a concrete barrier marker 96 or the like. Adhesive mounting systems are presently preferred.
In a given refLector 60, the in terrelationship between the vertical height 83 of body Sl above the face 52 of body 49 and the transverse distance 84 across the face 52 of body 49 is such tl~t preferably a minimum predetermined specific intensity vaLue for retroreflectivity in candelas per foot candle exists for reflector 60 with respect to incident and retroreflected light passing the forward tip edge 86 of body 49 at or along a negative angle 88 of pre-determined value (such as -59 relative to a tangent line 87 extending parallel to the surface of face 52, but perpendicularly to side 57 of body ~9 which tangent line represents 0. The exact angle (not shown) at which, for example, incident light rays a~ some predetermined such negative angle 88 strike the face 53 is unimportant so long as such minimum predetermined specific intensity value is achieved in fact, as those skilled in the art will understand. For example, at a negative angle 88 of -5 (presently preferred), a reflector 60 preferably has a minimum specific intensity value for retroreflectivity which is at least that shown in the following Table:
TABLE II
Color of bodies 49 and 51 Specific intensity value in candela per foot candle White 10 Red 2. 5 A mber 6 Blue 2. 5 Also preferably in such a given reflector 60, at an angle 89 of predetermined value above 60, but less than 90, measured perpendicularLy to tangent line 87 and to side 67 of body 49, a minimum predetermined specific intensity value for retroreflectivity in candelas per foot candle exists for reflector 60 with respect to incident and retroreflected Light at or along such angle 89. For example, aL a positive angle 89 of 75 (presently preferred), a reflector 60 preferably has a minimum specific intensity value for retroreflectivi~y which is at least that shown in the following Table:
TA BLE III _ Color of Bodies 49 and 51 Specific in~ensi~y value in candelas per foot candle 6~4 White 10 Red 2. 5 Amber 6 Blue 2. 5 In general, the relationship between the bodies 49 and Sl in a reflector 60 is so selected that, between about the 0 cangent line 87 and an angle 91 of 60 measured perpendicularly tO tangent line 87 and to side 67 of body 49, reflector 60 is continuously retroreflective of incident light rays striking one or the other of faces 52 and 53, and such retroreflected light has a minimum intensity value as set forth in Table I above. Preferably, such a reflector 60 is continuously so retroreflective of incident light rays between about -5 and 75~ (measured relative to tangent line 87) so that Tables I, II and III are satisfied.
In Fig. 8 there is shown a representative plot in rectangular coordinates illustrating characteristic speciHc intensity values of retroreflected light frorn each of the bodies 49 and 51 of a reflector 60 at each of several different retroreflective light values, respectively. Thus, curves 9LA, 91B, and 9lC are represencative of retroreflected light from body 49 at respective percentages of 100%, 30% and 10%, and curves 92A, 92B and 9~C are representative at respective percentages of l00~,, 30~ and 10% of retroreflected light from body 51. Gurves 91A and 92A are each a point. The retroreflection from each respective body 49 and Sl adds togecher in use of a refleçtor 60 producing composite curves connected by dotted lines in F ig. 8. Observe that the intersection of 0 horizontal angle represenrs the direction parallel to the tangent to the roadway at the point at which the reflector 60 is mounted, it must be remembered that the reflector 51, here with standard cu~e corner optics of the cube corner type has been tilted 10 from the perpendicular to the roadway.
When reflector 60 is mounted with layer 78 against the surface of a support 82, such as a guard fence, post, or the like, as desired, reflector 60 thus becomes mounted in a permanent manner resistant to attack by weather, and the environment. When being mounted, reflector 60 is spat~ally oriented so t~t face 52 is generally parallel to a tangent to an adjacent roadway side edge portion while side 67 is generally perpendicular to the surface of the adjacent roadway. Thus, reflector 6G as so mounted is viewable by the driver of a vehicle moving along such roadway continuously through an angle of from at least about -5 to 75 in relation to such tangent.
When reflector 60 is so mounted relative tO a roadway, body 51 is facing substantially towards on-coming traffic but is tilted preferably about 10 into a roadway. Since body 51 incorporates standard retroreflective opticaL elements preferentially, there is thus approximately 25 of reflectivity on each side of a perpendicular to the face 53 so that the body 51 covers from a~out -15 to .35, such angles being measured frorn a direction paraLlel tO the tangent to the roadway at the point where each reflector 60 is mounted.
Bec~use the body 49 inco~pora~es so-calLed wide angle cu~e corner 2S type retroreflective opticaL units, and because the body 49 is mounted in a direction parallel to the flow of traffic, the wide angle optics peak at approxirnately 35 to a norrnal or perpendicular to face 52 or approximately 55 from such tangent to such roadway.
Reflection thus occurs predominantly in the region from + or -25 from such a 35 peak. Hence, while the standard units 62 are active to an angle of 35 into a roadway, the wide angle units 61 comrnence to become active at an angle of about 30 from the tangent to the roadway resulting in an approximate 5 overlap between the respective retroreflected light from body 49 and body 51. On an opposite side, the body 52 retroreflects 25 from the peak which is about 35 from a normal to the face 52 so therefore the body 49 is active to about 80 from the direction of the tangent to the roadway at the point where each reflector 60 is mounted approximately. ~hus, Ehe combined standard and wide angle reflectors such as 51 and 49 employed in a preferred embodiment of reflector 60 are active from abcut -15 to such tangent to the roadway through an angle of about +80 to such tangent in a particularly preferred embodiment.
For a given reflector 60, duly mounted along the side of a road as on a barrier or the like, the distance from a car moving along the road towards the reflector can be regardedas one leg of a triangle, and the distance from the car to the barrier can be regarded as another Leg of the triangle. Thus, for various distances a number of triangles can be created, each triangle including an entrance angle. A value can be established for the specific intensity at a given entrance angle.
Representative tests showing the relationship between specific entrance angles and specific intensity in candelas per foot candle are shown for the representative curves in Figure 16. In Figure 16 curve 96 is representative of that associated with a preferred t,vpe of errbodiment for a reflector 60. Curve 97 is representative of that associated with the prior art reflector 40. As shown in Fig.
16, reflector 40 characteristically produces only effective retroreflectance up to an angle of about 30 out into a roadway from a mounted position tangent to and adjacent the roadway under conditions of observation equivalent for each of respective curves 96 and 97.
The respective curves of Figures 8 and 16 also illustrate the importance of having individual retroreflective reflectors used in the practice of the system of the present invention have minimum specific intensity values for retroreflectivity. Vaiues below those herein in-dicated can result in the driver of an on-coming vehicle not being able ~o see individual reflectors, particularly in the case of inciement weather,or possibly in a situation where a slight film of atmospheric contamination (dirt) has become lodged over the face of a reflector, such as can and routinely does occur under actual field use conditions for barrier marker reflectors, as those skilled in the art will appreciate.
When one employs in the practice of the invention a reflector, such as a reflector 60, unusual and beneficial effects can result in terms of increased roadway safety. I`hus, when as shown, for example, in Figure 3 reflector 60 are mounted perhaps at intervals of say lû to 30 feet apart along the edge portions of a highway, depending on whatever the local or reglonal specificacions of a given highway depar~ment are, a driver of a vehicle proceeding down the road tends to experience a tunnel effect. The situation is as though the driver is moving down a lane marked on either side by a continuous pattern of retroreflected light so that the driver can see an individual reflector as one of a series of reflectors from the time that his headlights come into contact with the re~roreflective surface portions of the reflector until the time when the vehicle has moved to an angle which is in the range, as discussed above, from about 60 to 85 with respect to the reflector.
In contrast, in the case of prior art reflectors, the individual reflectors are down to a negligible value for retro-reflectance at angles beyond about 30 with respect to a car moving down the roadway so that such a tunnel effect is not achieved by the pra~tice of the prior art.
In the case of a curved road, the advantages of the system of lS the invention are, perhaps, even more readily appreciated. Thus, approaching a curve, a driver sees reflectors of the type utilized in the present invention at a distance. Each one of the reflectors seen has a different angle of entrance, the exact angle of entrance for any given reflector depending upon the radius of curva~re at the location of an individual reflector. Thus, for example, upon entering lane 31~ (referring to Figure 3), a driver may be viewing a reflector 60A at an angle of lO while further al~:sng the curve the driver sees another reflector 60B at an angle of say 30~ and still farther along another reflectcr 60C at an angLe of say 45 and stiLl further on another reflector 60D at an angle of 60 possibly still another reflector at an angle of 80 designated 60e. Now, with a reflector 60, since such reflectors are activeLy retroreflective through aLl of these angles, one sees the 3~i34 complete curve ahead at the time one approaches the curve as the driver of a vehicle. In the case of the prior art, the reflectors fail to operate beyond about 30 at a maximum independently of the type of reflector use, so that the definition of the curve was S lost as soon as the driver approached that curve at an angle of greater than 30 which meant that the driver was seeing only a portion of the curve and then nothing beyond that.
In place of reflector 60 one can employ other forms of retro-reflective reflector means which have characteristics such as are IG generally above indicated. Thus, referring to Figures 9 and lO, there is seen another embodiment of a reflector construction suitable for use in the practice of this invention, such construction being designated in its entirety by the numeraL 101. Reflector construction 101 is provided with a backing member 102 of lS integral one piece rigid construction and including a base portion which is flattened and an upstanding peripherally extending flange portion. The backing member 102 is here comprised of a molded plastic member, but could be comprised of sheet metal, or the like, as desired.
~0 Reflector construction 101 incorporates a single three-primary sided retroreflective body 103 whose upper face has molded thereinto wide angLe type cu~e corner retroreflective units analogous to those formed in flattened inner face 54 of body 49. A front wall portion 1~4 of body 103 has integrally molded thereinto standard type cube corner retroreflective units analogous to those formed in the inner face 56 of flattened body 51. T'he reflector construction lOI is conveniently provided with a construction terminating in an inhesive - 3û
outer layer lOlA analogous to that employed for the reflector 60.
The angular relationships described above in reference to reflector 60 are similarly applicable to reflector 101, as those skilled in the art will appreciate. The face IOIB opposed to layer IOIA may have formed thereon two different groups of wide angle cube corner elements, as shown.
Another reflector construction 108 is shown in Figure 11 which will produce a reflected pattern of light similar to that achieved with a reflector 60. Reflector 108 employs a backing member 109 that includes a base member 110 and an integral upstanding leg member 111. The reflector construction 108 has reflective body 112 integrally formed with a reflective body 113. Body 112 has formed therein two classes of cube corner type retroreflective units 112A
and 112B, while body 113 has for;ned therein another class of such units.
The angular performance described above in reference to reflector 60 is similarly applicable to reflector 108 by employing a suitable orientation for the optical axes of the respective classes of cube corner units in bodies 112 and 113.
Referring to Figures 12 and 13 there is seen an embodiment of a reflector construc~ion 116 which is similar tO ~onstruction 101.
Reflector 116 employs a mechanical mounting means. Thus. outwardly extending mounting flanges 122 (paired), each one at a different end of reflector 116, terminate in thickened apertures 123 (one in each flange 122). A rivet, nut and bolt assembly, or the like, (not shown) can then be extendçd through each flange 122 to mount reflector 116 as desired. Reflector 116 employs an integrally formed pair of 3~i~4 recroreflective surfaces 127 and 12~ both containing cube corner type retroreflective units 129 and 130 molded thereinto. Units 129 can have their respective optical axes inclined at an angle of about 35 relative to a perpendicular to face 127, while units 130 can have their respective optical axes inclined at an angle of about 30 relative to a perpendicular to face 128, for example. The combination of retroreflective performance from each of said faces 127 and 128 results in a wide angle zone of retroreflectivity of from about 0 to 60. Face 127 is inclined at an angle 125 of about 200 to 210.
Still another type of reflector construction adapted for use in the practice of the present invention is shown in Figures 14 and 15 and is designated in its entirety by the numeral 131. Reflector construction 131 ~omploys a backing member 130 which incorporates integrally a mounting leg 132 and an arm 133. Arm 133 has three flattened facial regions 134, 135, and 136. On each exterior forward surface of respective regions 134; 135, and 126 is mounted a sheet of material having incorporated thereinto a plurality of glass beads, such a sheet being one of the Iype available commercially under the trademark r~cotch Light" or the like fromJ Minnesota Mining and Manufacturing Company, St. Paul, Minnesota. The three resulting sheet coated faces 134, 135, and 136 provide a continuous distribution of retroreflected light through the range of from about 0 to 60~ as desired. By using respective areas for faces 134, 135, and 136 which are sufficient to produce minimum specific intensity values for achieving the desired minimum candela per foot candle values above indicated for white cube corner type systems, reflector constructions are producable which are adapted for use in the practice of the present invention.-Referring to Figure 23 there is seen an embodiment 60' of a reflector similar to reflector 60 in construction is provided with a S layer 78' which is directly applied to a barrier 96'. The components shown in Fig. 23 are similar to those shown in Figs. 4-7 for example, and are similarly numbered but with the addition of p rime ma rks the reto .
Referring to Figs. 20-22, there is seen an embodiment 60" of a reflector similar to reflector 60 in cons~ruction which is pro-vided with wing-type dihedral integral flanges 201 and 202 for mounting reflec~or 60" to a guard rail 203 between a pair of adjacent convolutions 204 and 2ûS thereof. An adhesive, such as a self-curing epoxy resin or the like, is applied to outside surfaces IS of each flange 201 and 202 and the reflector 60' is manually set in pLace with the adjacent sùrface portions of guard rail 203 being in parallel reLationship to the respective flanges 201 and 202. Apertures 206 defined in each flange 201 and 202 have tapered side walls so that any adhesive which oozes thereinto before setting when a reflector 60 is in place is, in effect, aiding in bonding a reflector 60 to an adjacent guard rail 203. For mounting purposes, the size and shape of the flanges 201 and 202 can ~ary widely, as can the size and location of any apertures 206 used, in any given embodiment.
Referring to Fig. 17, there is seen an actuaL instaLlation of a system of this invention which involves highway 53 and Palatine Road northwest of Chicago, Illinois; highway 53 being designated by the numeral 154 and Palatine Road being designated by the numeral 153 Reflectors each similar tO reflector 60 are mounted on highway 154 on either side of the bridge abu~ment 155 each at a distance of about 30 inches vertically above the highway 154 surface. These reflectors are longitudinally spaced from one another successively at intervals of about 30 feet. There are 9 such reflectors on one side of the abutment 155 and 12 such reflectors on the opposing side thereof. For convenience here, these reflectors are each marked with a dash mark and designated by the number 156. Thus.
the drivers of vehicles moving in opposed directions along highway 154 see the individual reflectors 156 at night time on their respective sides of the bridge abutment 155; each reflector 156 is viewable within an angle extending from about -15 to about +75, as these angles are explained above, with 0 being a tangent to the highway 154.
Trace 157 is representative of retroreflectance from a single reflector 156A. The driver of a vehicle 158 entering highway 154 on cloverleaf 159 sees reflector 156A commencing at position 160.
Such driver continues to see such reflector L56A thereafter con-tinuously until the vehicle enters highway 154 and has almost moved past such reflector 156A. In contrast, when prior art reflectors, such as a reflector 40, replaces reflector 154A, a trace 157A
results, so that the same driver then does not see such reflector 40 until, on cloverleaf 159 he reaches location 161 at which location 161 such prior art reflector 40 becomes retroreflectively visible to him. Also such driver loses sight of such reflector 40 well back of the reflector 40 at position 162 a~ which location 162 loses its retroreflectivity relative to such driver. There is thus a dramatic difference between these two reflectors. Obviously, all the other reflectors 156 are likewise each visible through a greatly expanded viewing angle compared to the prior art.
Traces 163 and 164 similarly show the advantage of the present inven~ion over the prior art in reference to for example, the driver of a vehicle 165 in relation to ~he trace 163, or, for another example, the driver of a vehicle 166 relative to the trace 164. The dotted lines 167 and 168 iliustrate respective traces for prior art reflectors such as reflector 40 replacing 156B and 156C-, respectively.
The reflector shown in Fig. 18, which is designated in its entirety by the numeral 171 may be regarded as an improved version of the prior art reflector shown in Fig. 2, the improvements being such as to render the resulting reflector 171 adapted for use in the practice of the present invention. Ihe tangential or 0 direction along which a vehicle would move past an individual such reflector 171 in a system of this invention is marked by the arrow 172. The reflector 171 is comprised of a molded reflector body L73 having an integral front face 174 and an integral top face 175. A back face 170 is also integral with body 173 which facc 170 is flat and incLined at an angle 169 of preferably about 20 relative to a perpendicular 168 to back plate 176 which angle 169 is employed for ease in molding and complete the construction. Note that surface 1~9 has no optical function. ~ody 173 is bonded to a baok sealing plate member 176.
A perpendicular 177 to front face 174 is used tO illustrate and demonstrate the circumstance that the bac~ of front face 174 has formed (molded) thereinto a plurality of cube corner type retro-il~3~&;~4 reflective units 178 which have their respective individual cube axes (illustrated by line 179) all identicalLy aligned at an angle of from about 30 to 40 with 35 being preferred relative to perpendicular 177. The front face 174 is inclined to the tangent line 172 at an angle of from about 25 to 3~ with 30 being preferred.
In reflector 171, the top face 175 has molded into its back a plurality of cube corner type retroreflective units 180 which have their respective individual cube axes (illustrated by line 181 all identically aligned at an angle of from about 25 to 35 with 30 being preferred relative to a perpendicular 183 to top face 175. The uni~s 180 provide added angled reflector cubes for improved wide angle signal retroreflectance. Top face 175 is substantially parallel to tangent 172. An adhesive layer or tape 184 is spread over the member 176 to permit reflector 171 to be mounted upon a substrate 185 as a barrier marker for use in the practice of the present invention. The reflector 171 extends the region of retroreflectivit:y possessed by reflector 40 from about +25 to about +80 and the minimum specific intensity values for retroreflectivity of a reflector 171 are chosen so as to be in accord wi~h Table I.
The reflector 188 shown in Fig. 19 in performance is similar, for example, to that shown in Fig. Ll and designated reflector 109.
Reflector 188, however, employs separately formed retroreflective bodies 189a and 189b which are each mounted upon a single backing plate 190. An apermre 191 and an aport~re 192 which are preformed in the respective plate 190 and body 189a and which are aligned in the assembled reflector 188 provide a means for mounting reflector 188, as by means of a nut and bolt arrangement 193 tO a post 194 or the ~1f~36~ 4 like. Bodies 189a and 1~9b are conveniently welded sonically to plate 190.
A reflector used in the present invention has at least two retroreflective regions because of the need to achieve in a small area a minimum specific intensity value for retroreflectivity as indicated above (see Tables I, II and III). Preferably, che total surface area of retroreflectivity associated with a reflector used in this invention is under about 20 square inches, and more preferably under about 8 s~uare inches.
A reflector used in the present invention should not retroreflect beyond about 90, all as described herein, becsuse, beyond 90 the retroreflected signal is entering the zone of a driver possibly driving in the wrong direction, against oncoming traffic, whereby the retroreflected signal would falsely indicate that he is driving in a correct direction. Thus, a marker which permits a signal in the wrong direction (beyond 90 to the tangent to the roadway) would create ~nore of a hazard than the absence of a marker completely.
Although the teachings of our invention have herein been discussed with referencP ~o specific theories and embodiments, it is to be understood that these are by way of illustration only and that others may wish tO utilize our invention in different designs or applications.
In addition, it is a further characteristic of such prior art reflectors 40 that reflected ligh~ output, or performance of retro-S reflectivity, decreases with increasing angles from 0 (or the tangent to the roadway). In other words, the amount of light that the driver of a vehicle 25, 26, or 31 sees as he moves his vehicle down a lane such as 32, 21, or 23 continuously declines from an individual retroreflector 40 as the angle of viewing of each individual reflector 40 increases towards 25 or 30 when each reflector 40 becomes invisible to a driver as respects retro-reflected light.
As a consequence of the above characteristics, a driver's field of view as he proceeds along a road equipped with prior art reflectors 40 is such that a non-reflectorized zone in this field of view is entered regularly at very brief distances and intervals along the road corresponding to individual reflectors. Thus, when a driver is proceeding down a straight road, a blinking or fluttering light pattern is produced from individual reflectors 40 when a driver is proceeding along a road, particularly along a curved roadway which has an increasing degree of curvature with increasing distance along the road. Conse~uently, a driver has increasingly less delineation of a road ahead in the curved road situation owing to the inherent limitations of suoh prior art retroreflectors. Such limitations on retroreflective viewability cause serious night time motorist hazards.
To overcome such hazards, the present invention provides a roadside barrier marker system employing cube corner type retro-reflectors which retroreflect continuously through an angle of at least about 60 ~rom 0 (located paraLlelly to a road). Re~Lectors used in the system of the present invention are so constructed, mounted and oriented relative to a given road that the driver of a vehicle moving along such road equipped with headlight means can continuously see individual reflector means within a viewing Line angle of from about 0 to 6û, where 0 extends substantially parallelly to a tangent to one of the roadside edge portions in the region where the reflector is mounted.
One exemplary embodiment of a barrier marker system of the present invention is illustrated in Figure 3 wherein is shown a modern divided highway construction which is similar to that shown in Figure 1 and described above. For reasons of convenience and brevity, similar elements in Figure 3 corresponding to those in Figure I are similarLy numbered but with the addition of prime marks thereto.
Here, highway 20' and ramp 3G' are each provided and equipped with reflectorized barrier or road edge markers which are each for convenience herein entirely designated by the numeral 60. Like the refLectors 40, the reflectors 60 are located along road side edge portions in su~stitution for the individual positions occupied by the reflectors 40.
Each reflector 60 is adapted to retroreflect Light through a max-imum angle ranging at least from about -5 ~hrough about 75. The included angle of retrore1ectivity for each reflector 60 is so arranged (by orienting each reflector 60 relative to highway 20' and ramp 30') that retrorefle~tlvity extends generalLy from a postion approximately 5 to the outside of a tangent to the road edge at the location of an individual reflector 60 out into the roadway at an angle of about 75 maximum. Each of the reflectors 60 illustrated in Figure 2 along the highway 20' and the ramp 30' is provided with a pair of intersecting broken Lines to illustrate an included angle of 80 through which light is retroreflected as respects incident rays striking retroreflective portions of an individual reflector 60. As can be seen, the driver of each of the vehicles 25', 26' and 31~ is able to view each individual road side reflector 60 (as respects retroreflected light) through a ~TIaximum angle ~rpically greater than about 80. Thus each such driver continuously is able to see by retroreflected light each individual reflector 60 during the entire time interval that the respective vehicle involved remain behind and approaching an individual reflector 60.
The candela per foot candle signal that the driver of a vehicle 25', 26' or 38' sees as he moves his vehicle down a lane such as 32', 21' or 23' remains relacively constant, particularly in the angular range between about 0 and 60.
As a consequence of the above characteristics, a driver's field of view as he proceeds along a road equipped with the reflector 60 is such that no non-reflectorized zone in this field of view is entered for an indivi~ual reflector as a vehicle such as 38', 25' or 26' moves down the road until such vehicle nears an angle of 90 with respec~ to an individual reflector 60 adjacent theret~, respectiveLy.
Thus, the limitations on retroreflective viewability associated with prior ar~ reflectors 40 is su~s~antially completely eliminated.
One exemplary embodiment of a reflector construction of the present invention is shown in Figures 4 through 7 and is designated in its entirety by the numeral 60. Reflector construction 60 is provided with a backing member 44 of integral one-piece rigid S construction. The backing member 44 has a base portion 46 which is flattened and an inclined (relative to base portion 46) leg portion 47 which is Likewise flattened. Leg portion 47 upstands at an inclined angle 55 along one edge 48 of the base portion 46. Angle 55 ranges from about 60 to 85~; and preferably from about 75 to 85. In reflector 60, angle 55 is about 80 which is presently a most preferred incLination angle. The backing member 44 is preferably comprised of a molded thermoplastic or thermosetting plastic composition, such as one comprised of ABS, nylon, polyester, or the like, but alternatively may be formed of a sheet metal, or the like, as desired.
Reflector construction 60 incorporates two molded transparent retroreflective flattened rectangularly sided bodies 49 and 51 which can be comprised of a plastic, such as an acrylic or a polycarbonate resin. Each such body 4~ and 51 has a flattened oucer face 52 and 53 respectively, as well as an inner face 54 and 56, respectively, which is generally parallel to its respective outer face 52 and S3 Each inner face 54 and S6 has formed thereinto a plurality of individual cube corrler cype retroreflective units 61 and 62, respectively. A 11 units 61 in inner face 54 are arranged so as ;o b generally coplanar relative to one another, and similarly for all the units 62 in inner face 56, respectively. An inturned peripheral shoulder 57 and 58, respecti~ely, extends about each body 49 and 51, and projec~s beyond itS respective associated inner face 54 and 56. Each such shoulder 57 and 58 preferably and as here illustrated terminates in an outturned flange 68 and 69, respectively, ~o pro-S vide a mounting surface. Preferably, both bodies 49 and 51 have the same color in an indi~,-idual reflector 60 construction. The surface area of outer face 52 is preferably from about 1. S to 3. 5 times larger than the surface area of outer face 53, though this ratio can vary greatly in practice without departing from the present invention.
Bodies 49 and ~I have their respective flanges 6~ and 69 positioned against, and mounted tO, base 46 and Leg 47 of backing member 44, respectively. Any convenient mounting means for b odies 49 and 51 may be employed, such as an adhesive, or the Iike, but here ultrasonic welding is employed preferentially and as illustrated. During assembly, body 51 is first rnounted to leg 47, and then body 49 is mounted to base 46. Flange 68 is provided with a spacing ear 71 integrally formed therewith which serves to locate and orient body 49 relative to backing member 44 and body 51 in a desired manner before ultrasonic welding (see Fig. 7).
Preferably, and as shown, integrally formed ribs 73 and 74 upstand from the opposed sides of base 46 and leg 47, respectiveLy, and integrally formed rlb 76 upstands from the forward edge of base 46. Ribs 73, 76 and 74 are joined end to end with one another integrally. Ribs 73, 74 and 76 aid in rigidifying and strengthening backing merrlber 74, and aid in protecting edge portions of bodies 49 and 51 from bumps or impacts.
The general narure and conscruction of cube corner type retroreflective units and reflectors utilizing same is well known; see, for instance, the disclosure contained in U. S. Pats. 3, 894, 786 or 3,893,747, or that in the Heenan and Nagel El.S.P. 3,541,606 and elsewhere .
In a reflector construction 60, when angle 55 is in the preferred range above indicated, the cube corner units 62 of retroreflective body 51 are preferably of the so-called standard type. Thus, the respective optical axes (not detailed) of the individual respective units 62 are preferably normal to the outer face 53 thereof, and retroreflective body Sl is then adapted to retroreflect light rays incident against face 53 through a solid cone angle 63 of up to about 25 to 30 around a perpendicular 64 to face 53, as those skilled in the art will appreciate. The cube corner retroreflective units in body 51 have optical axes which are parallel to one another and which are generally inclined at an angle of frorn about 0 to 15 with respect to a perpendicular 64 to the face 53 of body 51. Retroreflective body Sl is adapted to retroreflect light rays incident against face 53 up to about 50 relative to one side of the prependicular 64.
In order to minimize the characteristic so-called clover-leaf pattern of retroreflection associated with retroreflection from a single group of standard cube corner units which are all similarly oriented, and to make suoh pattern more uniform and circular, it is preferred, but not necessary, to divide the units 6~ into two equally sized groups, and to rotate the axes of the units of one group 180 with respect to ~he axes of the units of the other group.
As shown in Fig. 4, in retroreflective body 51, such an arrangement is used so that one gr~p 62A is formed in the inner face 56 in the upper haLf of the body 51 while a~lother group 62B is formed in the inner face 56 in the lower half of the body 51.
Also, in reflector 60, the cube corner units 61 of retro-reflective body 49 are preferably of the so-called wide angle type.
Thus, the respective optical axes, illustrated by line 59, of the individual respective units 61 are inclined at an angle 66 of from about 20 to 35 (preferably 25 to 309 with respe~t to a perpendicular 65 to outer face 52 of flattened retroreflective body 49. Thus, ligh~ rays within an included angle 94 of from about 65 to 75 to one side of perpendicular 65 to about 5 to l5 to the same side of perpendicular 65 striking face 52 are retroreflected. The orientation of angle 94 is such that the location of its greatest lateral or side projection istowards side 67 of body 49. Thus, when body 49 is mounted on base 46, as shown, for example, in Figs. 4 and 6, the orientation of body 49 is such that body 49 is retroreflective of incident light rays striking against face 52 from locacions lateral and outside of side 67 and from directions generally opposite to those from opposed locations beyond leg 47 and body 51.
If desired, each body 49 and 51 can have formed therein more than one group of cube corner retroreflective units. Each such group can have its optical axes of individual units all parallel to one another in each body 49 or 51. Ihe axes of one such group can ~e rotated wich respect to a second such group, for example, or the axes of one sslch group within the angular relationships herein above indicated, or both, if desired.
~3~6~4 Preferably a reflector such as refLector 60~ has a base portion and a leg portion which are each rectangular in perimeter configuration. A lso preferably, the leg portion has a transverse width measured from the acute angle formed between the leg portion and the base portion which is not more than about one-half the transverse width measured from such acute angle of the base portion in a reflector, such as reflector 60.
Any convenient mounting means or technique may be employed.
One technique for moun~ing a reflector 60 is to appLy over the back surface 77 of base 46, an adhesive layer 78, comprised of, for example, a butyl rubber based pressure sensitive adhesive tape~
or the like. Until the time of application, the exposed surface of layer 78 can be covered by a coated paper release sheet, or equivalent, if desired (removed and not shown). Layer 81 is an optional but not preferred adhesive cushioning layer applied between layer 78 and a concrete barrier marker 96 or the like. Adhesive mounting systems are presently preferred.
In a given refLector 60, the in terrelationship between the vertical height 83 of body Sl above the face 52 of body 49 and the transverse distance 84 across the face 52 of body 49 is such tl~t preferably a minimum predetermined specific intensity vaLue for retroreflectivity in candelas per foot candle exists for reflector 60 with respect to incident and retroreflected light passing the forward tip edge 86 of body 49 at or along a negative angle 88 of pre-determined value (such as -59 relative to a tangent line 87 extending parallel to the surface of face 52, but perpendicularly to side 57 of body ~9 which tangent line represents 0. The exact angle (not shown) at which, for example, incident light rays a~ some predetermined such negative angle 88 strike the face 53 is unimportant so long as such minimum predetermined specific intensity value is achieved in fact, as those skilled in the art will understand. For example, at a negative angle 88 of -5 (presently preferred), a reflector 60 preferably has a minimum specific intensity value for retroreflectivity which is at least that shown in the following Table:
TABLE II
Color of bodies 49 and 51 Specific intensity value in candela per foot candle White 10 Red 2. 5 A mber 6 Blue 2. 5 Also preferably in such a given reflector 60, at an angle 89 of predetermined value above 60, but less than 90, measured perpendicularLy to tangent line 87 and to side 67 of body 49, a minimum predetermined specific intensity value for retroreflectivity in candelas per foot candle exists for reflector 60 with respect to incident and retroreflected Light at or along such angle 89. For example, aL a positive angle 89 of 75 (presently preferred), a reflector 60 preferably has a minimum specific intensity value for retroreflectivi~y which is at least that shown in the following Table:
TA BLE III _ Color of Bodies 49 and 51 Specific in~ensi~y value in candelas per foot candle 6~4 White 10 Red 2. 5 Amber 6 Blue 2. 5 In general, the relationship between the bodies 49 and Sl in a reflector 60 is so selected that, between about the 0 cangent line 87 and an angle 91 of 60 measured perpendicularly tO tangent line 87 and to side 67 of body 49, reflector 60 is continuously retroreflective of incident light rays striking one or the other of faces 52 and 53, and such retroreflected light has a minimum intensity value as set forth in Table I above. Preferably, such a reflector 60 is continuously so retroreflective of incident light rays between about -5 and 75~ (measured relative to tangent line 87) so that Tables I, II and III are satisfied.
In Fig. 8 there is shown a representative plot in rectangular coordinates illustrating characteristic speciHc intensity values of retroreflected light frorn each of the bodies 49 and 51 of a reflector 60 at each of several different retroreflective light values, respectively. Thus, curves 9LA, 91B, and 9lC are represencative of retroreflected light from body 49 at respective percentages of 100%, 30% and 10%, and curves 92A, 92B and 9~C are representative at respective percentages of l00~,, 30~ and 10% of retroreflected light from body 51. Gurves 91A and 92A are each a point. The retroreflection from each respective body 49 and Sl adds togecher in use of a refleçtor 60 producing composite curves connected by dotted lines in F ig. 8. Observe that the intersection of 0 horizontal angle represenrs the direction parallel to the tangent to the roadway at the point at which the reflector 60 is mounted, it must be remembered that the reflector 51, here with standard cu~e corner optics of the cube corner type has been tilted 10 from the perpendicular to the roadway.
When reflector 60 is mounted with layer 78 against the surface of a support 82, such as a guard fence, post, or the like, as desired, reflector 60 thus becomes mounted in a permanent manner resistant to attack by weather, and the environment. When being mounted, reflector 60 is spat~ally oriented so t~t face 52 is generally parallel to a tangent to an adjacent roadway side edge portion while side 67 is generally perpendicular to the surface of the adjacent roadway. Thus, reflector 6G as so mounted is viewable by the driver of a vehicle moving along such roadway continuously through an angle of from at least about -5 to 75 in relation to such tangent.
When reflector 60 is so mounted relative tO a roadway, body 51 is facing substantially towards on-coming traffic but is tilted preferably about 10 into a roadway. Since body 51 incorporates standard retroreflective opticaL elements preferentially, there is thus approximately 25 of reflectivity on each side of a perpendicular to the face 53 so that the body 51 covers from a~out -15 to .35, such angles being measured frorn a direction paraLlel tO the tangent to the roadway at the point where each reflector 60 is mounted.
Bec~use the body 49 inco~pora~es so-calLed wide angle cu~e corner 2S type retroreflective opticaL units, and because the body 49 is mounted in a direction parallel to the flow of traffic, the wide angle optics peak at approxirnately 35 to a norrnal or perpendicular to face 52 or approximately 55 from such tangent to such roadway.
Reflection thus occurs predominantly in the region from + or -25 from such a 35 peak. Hence, while the standard units 62 are active to an angle of 35 into a roadway, the wide angle units 61 comrnence to become active at an angle of about 30 from the tangent to the roadway resulting in an approximate 5 overlap between the respective retroreflected light from body 49 and body 51. On an opposite side, the body 52 retroreflects 25 from the peak which is about 35 from a normal to the face 52 so therefore the body 49 is active to about 80 from the direction of the tangent to the roadway at the point where each reflector 60 is mounted approximately. ~hus, Ehe combined standard and wide angle reflectors such as 51 and 49 employed in a preferred embodiment of reflector 60 are active from abcut -15 to such tangent to the roadway through an angle of about +80 to such tangent in a particularly preferred embodiment.
For a given reflector 60, duly mounted along the side of a road as on a barrier or the like, the distance from a car moving along the road towards the reflector can be regardedas one leg of a triangle, and the distance from the car to the barrier can be regarded as another Leg of the triangle. Thus, for various distances a number of triangles can be created, each triangle including an entrance angle. A value can be established for the specific intensity at a given entrance angle.
Representative tests showing the relationship between specific entrance angles and specific intensity in candelas per foot candle are shown for the representative curves in Figure 16. In Figure 16 curve 96 is representative of that associated with a preferred t,vpe of errbodiment for a reflector 60. Curve 97 is representative of that associated with the prior art reflector 40. As shown in Fig.
16, reflector 40 characteristically produces only effective retroreflectance up to an angle of about 30 out into a roadway from a mounted position tangent to and adjacent the roadway under conditions of observation equivalent for each of respective curves 96 and 97.
The respective curves of Figures 8 and 16 also illustrate the importance of having individual retroreflective reflectors used in the practice of the system of the present invention have minimum specific intensity values for retroreflectivity. Vaiues below those herein in-dicated can result in the driver of an on-coming vehicle not being able ~o see individual reflectors, particularly in the case of inciement weather,or possibly in a situation where a slight film of atmospheric contamination (dirt) has become lodged over the face of a reflector, such as can and routinely does occur under actual field use conditions for barrier marker reflectors, as those skilled in the art will appreciate.
When one employs in the practice of the invention a reflector, such as a reflector 60, unusual and beneficial effects can result in terms of increased roadway safety. I`hus, when as shown, for example, in Figure 3 reflector 60 are mounted perhaps at intervals of say lû to 30 feet apart along the edge portions of a highway, depending on whatever the local or reglonal specificacions of a given highway depar~ment are, a driver of a vehicle proceeding down the road tends to experience a tunnel effect. The situation is as though the driver is moving down a lane marked on either side by a continuous pattern of retroreflected light so that the driver can see an individual reflector as one of a series of reflectors from the time that his headlights come into contact with the re~roreflective surface portions of the reflector until the time when the vehicle has moved to an angle which is in the range, as discussed above, from about 60 to 85 with respect to the reflector.
In contrast, in the case of prior art reflectors, the individual reflectors are down to a negligible value for retro-reflectance at angles beyond about 30 with respect to a car moving down the roadway so that such a tunnel effect is not achieved by the pra~tice of the prior art.
In the case of a curved road, the advantages of the system of lS the invention are, perhaps, even more readily appreciated. Thus, approaching a curve, a driver sees reflectors of the type utilized in the present invention at a distance. Each one of the reflectors seen has a different angle of entrance, the exact angle of entrance for any given reflector depending upon the radius of curva~re at the location of an individual reflector. Thus, for example, upon entering lane 31~ (referring to Figure 3), a driver may be viewing a reflector 60A at an angle of lO while further al~:sng the curve the driver sees another reflector 60B at an angle of say 30~ and still farther along another reflectcr 60C at an angLe of say 45 and stiLl further on another reflector 60D at an angle of 60 possibly still another reflector at an angle of 80 designated 60e. Now, with a reflector 60, since such reflectors are activeLy retroreflective through aLl of these angles, one sees the 3~i34 complete curve ahead at the time one approaches the curve as the driver of a vehicle. In the case of the prior art, the reflectors fail to operate beyond about 30 at a maximum independently of the type of reflector use, so that the definition of the curve was S lost as soon as the driver approached that curve at an angle of greater than 30 which meant that the driver was seeing only a portion of the curve and then nothing beyond that.
In place of reflector 60 one can employ other forms of retro-reflective reflector means which have characteristics such as are IG generally above indicated. Thus, referring to Figures 9 and lO, there is seen another embodiment of a reflector construction suitable for use in the practice of this invention, such construction being designated in its entirety by the numeraL 101. Reflector construction 101 is provided with a backing member 102 of lS integral one piece rigid construction and including a base portion which is flattened and an upstanding peripherally extending flange portion. The backing member 102 is here comprised of a molded plastic member, but could be comprised of sheet metal, or the like, as desired.
~0 Reflector construction 101 incorporates a single three-primary sided retroreflective body 103 whose upper face has molded thereinto wide angLe type cu~e corner retroreflective units analogous to those formed in flattened inner face 54 of body 49. A front wall portion 1~4 of body 103 has integrally molded thereinto standard type cube corner retroreflective units analogous to those formed in the inner face 56 of flattened body 51. T'he reflector construction lOI is conveniently provided with a construction terminating in an inhesive - 3û
outer layer lOlA analogous to that employed for the reflector 60.
The angular relationships described above in reference to reflector 60 are similarly applicable to reflector 101, as those skilled in the art will appreciate. The face IOIB opposed to layer IOIA may have formed thereon two different groups of wide angle cube corner elements, as shown.
Another reflector construction 108 is shown in Figure 11 which will produce a reflected pattern of light similar to that achieved with a reflector 60. Reflector 108 employs a backing member 109 that includes a base member 110 and an integral upstanding leg member 111. The reflector construction 108 has reflective body 112 integrally formed with a reflective body 113. Body 112 has formed therein two classes of cube corner type retroreflective units 112A
and 112B, while body 113 has for;ned therein another class of such units.
The angular performance described above in reference to reflector 60 is similarly applicable to reflector 108 by employing a suitable orientation for the optical axes of the respective classes of cube corner units in bodies 112 and 113.
Referring to Figures 12 and 13 there is seen an embodiment of a reflector construc~ion 116 which is similar tO ~onstruction 101.
Reflector 116 employs a mechanical mounting means. Thus. outwardly extending mounting flanges 122 (paired), each one at a different end of reflector 116, terminate in thickened apertures 123 (one in each flange 122). A rivet, nut and bolt assembly, or the like, (not shown) can then be extendçd through each flange 122 to mount reflector 116 as desired. Reflector 116 employs an integrally formed pair of 3~i~4 recroreflective surfaces 127 and 12~ both containing cube corner type retroreflective units 129 and 130 molded thereinto. Units 129 can have their respective optical axes inclined at an angle of about 35 relative to a perpendicular to face 127, while units 130 can have their respective optical axes inclined at an angle of about 30 relative to a perpendicular to face 128, for example. The combination of retroreflective performance from each of said faces 127 and 128 results in a wide angle zone of retroreflectivity of from about 0 to 60. Face 127 is inclined at an angle 125 of about 200 to 210.
Still another type of reflector construction adapted for use in the practice of the present invention is shown in Figures 14 and 15 and is designated in its entirety by the numeral 131. Reflector construction 131 ~omploys a backing member 130 which incorporates integrally a mounting leg 132 and an arm 133. Arm 133 has three flattened facial regions 134, 135, and 136. On each exterior forward surface of respective regions 134; 135, and 126 is mounted a sheet of material having incorporated thereinto a plurality of glass beads, such a sheet being one of the Iype available commercially under the trademark r~cotch Light" or the like fromJ Minnesota Mining and Manufacturing Company, St. Paul, Minnesota. The three resulting sheet coated faces 134, 135, and 136 provide a continuous distribution of retroreflected light through the range of from about 0 to 60~ as desired. By using respective areas for faces 134, 135, and 136 which are sufficient to produce minimum specific intensity values for achieving the desired minimum candela per foot candle values above indicated for white cube corner type systems, reflector constructions are producable which are adapted for use in the practice of the present invention.-Referring to Figure 23 there is seen an embodiment 60' of a reflector similar to reflector 60 in construction is provided with a S layer 78' which is directly applied to a barrier 96'. The components shown in Fig. 23 are similar to those shown in Figs. 4-7 for example, and are similarly numbered but with the addition of p rime ma rks the reto .
Referring to Figs. 20-22, there is seen an embodiment 60" of a reflector similar to reflector 60 in cons~ruction which is pro-vided with wing-type dihedral integral flanges 201 and 202 for mounting reflec~or 60" to a guard rail 203 between a pair of adjacent convolutions 204 and 2ûS thereof. An adhesive, such as a self-curing epoxy resin or the like, is applied to outside surfaces IS of each flange 201 and 202 and the reflector 60' is manually set in pLace with the adjacent sùrface portions of guard rail 203 being in parallel reLationship to the respective flanges 201 and 202. Apertures 206 defined in each flange 201 and 202 have tapered side walls so that any adhesive which oozes thereinto before setting when a reflector 60 is in place is, in effect, aiding in bonding a reflector 60 to an adjacent guard rail 203. For mounting purposes, the size and shape of the flanges 201 and 202 can ~ary widely, as can the size and location of any apertures 206 used, in any given embodiment.
Referring to Fig. 17, there is seen an actuaL instaLlation of a system of this invention which involves highway 53 and Palatine Road northwest of Chicago, Illinois; highway 53 being designated by the numeral 154 and Palatine Road being designated by the numeral 153 Reflectors each similar tO reflector 60 are mounted on highway 154 on either side of the bridge abu~ment 155 each at a distance of about 30 inches vertically above the highway 154 surface. These reflectors are longitudinally spaced from one another successively at intervals of about 30 feet. There are 9 such reflectors on one side of the abutment 155 and 12 such reflectors on the opposing side thereof. For convenience here, these reflectors are each marked with a dash mark and designated by the number 156. Thus.
the drivers of vehicles moving in opposed directions along highway 154 see the individual reflectors 156 at night time on their respective sides of the bridge abutment 155; each reflector 156 is viewable within an angle extending from about -15 to about +75, as these angles are explained above, with 0 being a tangent to the highway 154.
Trace 157 is representative of retroreflectance from a single reflector 156A. The driver of a vehicle 158 entering highway 154 on cloverleaf 159 sees reflector 156A commencing at position 160.
Such driver continues to see such reflector L56A thereafter con-tinuously until the vehicle enters highway 154 and has almost moved past such reflector 156A. In contrast, when prior art reflectors, such as a reflector 40, replaces reflector 154A, a trace 157A
results, so that the same driver then does not see such reflector 40 until, on cloverleaf 159 he reaches location 161 at which location 161 such prior art reflector 40 becomes retroreflectively visible to him. Also such driver loses sight of such reflector 40 well back of the reflector 40 at position 162 a~ which location 162 loses its retroreflectivity relative to such driver. There is thus a dramatic difference between these two reflectors. Obviously, all the other reflectors 156 are likewise each visible through a greatly expanded viewing angle compared to the prior art.
Traces 163 and 164 similarly show the advantage of the present inven~ion over the prior art in reference to for example, the driver of a vehicle 165 in relation to ~he trace 163, or, for another example, the driver of a vehicle 166 relative to the trace 164. The dotted lines 167 and 168 iliustrate respective traces for prior art reflectors such as reflector 40 replacing 156B and 156C-, respectively.
The reflector shown in Fig. 18, which is designated in its entirety by the numeral 171 may be regarded as an improved version of the prior art reflector shown in Fig. 2, the improvements being such as to render the resulting reflector 171 adapted for use in the practice of the present invention. Ihe tangential or 0 direction along which a vehicle would move past an individual such reflector 171 in a system of this invention is marked by the arrow 172. The reflector 171 is comprised of a molded reflector body L73 having an integral front face 174 and an integral top face 175. A back face 170 is also integral with body 173 which facc 170 is flat and incLined at an angle 169 of preferably about 20 relative to a perpendicular 168 to back plate 176 which angle 169 is employed for ease in molding and complete the construction. Note that surface 1~9 has no optical function. ~ody 173 is bonded to a baok sealing plate member 176.
A perpendicular 177 to front face 174 is used tO illustrate and demonstrate the circumstance that the bac~ of front face 174 has formed (molded) thereinto a plurality of cube corner type retro-il~3~&;~4 reflective units 178 which have their respective individual cube axes (illustrated by line 179) all identicalLy aligned at an angle of from about 30 to 40 with 35 being preferred relative to perpendicular 177. The front face 174 is inclined to the tangent line 172 at an angle of from about 25 to 3~ with 30 being preferred.
In reflector 171, the top face 175 has molded into its back a plurality of cube corner type retroreflective units 180 which have their respective individual cube axes (illustrated by line 181 all identically aligned at an angle of from about 25 to 35 with 30 being preferred relative to a perpendicular 183 to top face 175. The uni~s 180 provide added angled reflector cubes for improved wide angle signal retroreflectance. Top face 175 is substantially parallel to tangent 172. An adhesive layer or tape 184 is spread over the member 176 to permit reflector 171 to be mounted upon a substrate 185 as a barrier marker for use in the practice of the present invention. The reflector 171 extends the region of retroreflectivit:y possessed by reflector 40 from about +25 to about +80 and the minimum specific intensity values for retroreflectivity of a reflector 171 are chosen so as to be in accord wi~h Table I.
The reflector 188 shown in Fig. 19 in performance is similar, for example, to that shown in Fig. Ll and designated reflector 109.
Reflector 188, however, employs separately formed retroreflective bodies 189a and 189b which are each mounted upon a single backing plate 190. An apermre 191 and an aport~re 192 which are preformed in the respective plate 190 and body 189a and which are aligned in the assembled reflector 188 provide a means for mounting reflector 188, as by means of a nut and bolt arrangement 193 tO a post 194 or the ~1f~36~ 4 like. Bodies 189a and 1~9b are conveniently welded sonically to plate 190.
A reflector used in the present invention has at least two retroreflective regions because of the need to achieve in a small area a minimum specific intensity value for retroreflectivity as indicated above (see Tables I, II and III). Preferably, che total surface area of retroreflectivity associated with a reflector used in this invention is under about 20 square inches, and more preferably under about 8 s~uare inches.
A reflector used in the present invention should not retroreflect beyond about 90, all as described herein, becsuse, beyond 90 the retroreflected signal is entering the zone of a driver possibly driving in the wrong direction, against oncoming traffic, whereby the retroreflected signal would falsely indicate that he is driving in a correct direction. Thus, a marker which permits a signal in the wrong direction (beyond 90 to the tangent to the roadway) would create ~nore of a hazard than the absence of a marker completely.
Although the teachings of our invention have herein been discussed with referencP ~o specific theories and embodiments, it is to be understood that these are by way of illustration only and that others may wish tO utilize our invention in different designs or applications.
Claims (20)
1. A reflector for improved roadside barrier marketing comprising (A) a backing member of integral, one piece, rigid construction having -- (1) a base flattened portion (2) an upstanding flattened leg portion along one edge of said base portion which is inclined in relation to said base portion at an angle ranging from about 60° to 85° (B) two molded transparent flattened bodies, each having a flattened outerface and an inner face with a plurality of cube corner type retroreflective units formed thereinto and further having an inturned peripheral shoulder which extends beyond its associated inner face, (1) one of said flattened bodies being larger than the other thereof and being adapted to fit against the inside face of said base portion with the edge portions of said shoulder thereof engaged thereagainst, (2) said other flattened body being adapted to fit against the inside face of said leg portion with the edge portions of said shoulder thereof engaged thereagainst, and (C) bonding means adhereing such respective shoulder edge portions to said backing member at such locations of engage-ment, (D) said flattened bodies in combination with said backing member being adapted to retroreflect incident light rays striking said outer faces thereof within an angle of about 60°
where 0° is taken along a hypothetical line which is generally parallel to the outer face of said one flattened body and which is generally perpendicular to the outer face of said other flattened body and where 60° is measured vertically upwards, from said 0° line and outwardly from the outer face of said one flattened body.
where 0° is taken along a hypothetical line which is generally parallel to the outer face of said one flattened body and which is generally perpendicular to the outer face of said other flattened body and where 60° is measured vertically upwards, from said 0° line and outwardly from the outer face of said one flattened body.
2. The reflector of claim 1 wherein said backing member has an integral upstanding rib member on opposed sides thereof with inside faces of said leg portion and said base portion being adjacent thereto.
3. The reflector of claim 1 wherein the cube corner type retroreflective units formed in said one flattened body have axes which are parallel to one another and which are inclined with respect to the outer face thereof at an angle of from about 25° to 35°.
4. The reflector of claim 1 wherein the cube corner type retroreflector units formed in said other flattened body have axes which are parallel to one another and which are inclined with respect to the outer face thereof at an angle of from about 0° to 15°.
5. The reflector of claim 1 wherein the respective said edge portions of each said flattened body is flattened and expanded laterally.
6. The reflector of claim 1 wherein said base portion has an upstanding rib member on the forward open edge thereof.
7. The reflector of claim 1 further including mounting means for mounting said reflector to a given support means with said outer faces being vertically oriented.
8. The reflector of claim 7 wherein said mounting means is an adhesive.
9. The reflector of claim 8 wherein said adhesive is layered on the outside face of said base portion.
10. The reflector of claim 8 wherein said adhesive is an epoxy resin.
11. The reflector of claim 7 wherein said adhesive is a butyl rubber type adhesive.
12. The reflector of claim 8 wherein said adhesive is a rubber based permanently tacky tape adhesive.
13. The reflector of claim 7 wherein said mounting means is mechanical.
14. The reflector of claim 1 wherein said angle ranges from about 75 to 85°.
15. The reflector of claim 1 wherein said angle is about 80°.
16. The reflector of claim 1 wherein the outer surface area of said one flattened body is 1.5 to 3.5 times greater than the outer surface area of said other flattened body.
17. The reflector of claim 4 wherein said cube corner type retroreflective units formed in said other flattend body have optical axes perpendicular to the outer face thereof.
18. The reflector of claim 3 wherein said cube corner type retroreflective units formed in said one flattened body have optical axes inclined at an angle of from about 25 to 30°
with respect to said perpendicular.
with respect to said perpendicular.
19. The reflector of claim 1 wherein said base portion and said leg portion are each rectangular in perimeter configura-tion, and said leg portion has a transverse width measured from said acute angle of not more than about one-half the transverse width measured from said acute angle of said base portion.
20. The reflector of claim 1 wherein said two bodies are colored white, red, amber, or blue, and wherein retro-reflected light therefrom within said included angle has a minimum specific intensity value for retroreflectivity which is at least that shown in the following table:
Color of such two regions Specific intensity value in candelas per foot candle White 20 Red 5 Amber 12 Blue 5
Color of such two regions Specific intensity value in candelas per foot candle White 20 Red 5 Amber 12 Blue 5
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US856,967 | 1977-12-02 | ||
US05/856,967 US4123181A (en) | 1977-12-02 | 1977-12-02 | Roadside barrier marker system |
US87617478A | 1978-02-08 | 1978-02-08 | |
US876,174 | 1978-02-08 |
Publications (1)
Publication Number | Publication Date |
---|---|
CA1103634A true CA1103634A (en) | 1981-06-23 |
Family
ID=27127386
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
CA312,679A Expired CA1103634A (en) | 1977-12-02 | 1978-10-04 | Roadside barrier reflector |
Country Status (1)
Country | Link |
---|---|
CA (1) | CA1103634A (en) |
-
1978
- 1978-10-04 CA CA312,679A patent/CA1103634A/en not_active Expired
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