US3850536A

US3850536A - Light-reflective road marker

Info

Publication number: US3850536A
Application number: US00210802A
Authority: US
Inventors: E Kone
Original assignee: TRAFFIC STANDARD Inc
Current assignee: TRAFFIC STANDARD Inc
Priority date: 1971-12-22
Filing date: 1971-12-22
Publication date: 1974-11-26
Anticipated expiration: 1991-11-26

Abstract

Road marker having a base cup with a resilient cover diphragm near the top, and an elongated, substantially flat and rigid light reflector lens with a rigid base mount in the middle of the diaphragm and below the top of the base cup, with the lens being normally in erect disposition on the diaphragm and extending above the top of the base cup, and the lens and diaphragm yielding to a vehicle tire or plow blade passing over the marker, with the lens yielding in tilting fashion to a passing plow blade.

Description

United States Patent 1191 Kone [ NOV. 26, 1974 LIGHT-REFLECTIVE ROAD MARKER [75] Inventor: Elliott H. Kone, Branford, Conn.

[73] Assignee: Traffic Standard Incorporated, New

Haven, Conn.

[58] Field of Search 94/15; 240/12; 404/9, 404/10, 11, 16,15

FORElGN PATENTS OR APPLICATIONS 528,622 11/1940 Great Britain 94/15 107,616 6/1939 Australia 94/l.5 372,069 11/1963 Switzerland... 94/l.5 545,039 /1942 Great Britain 94/1.5

Primary ExaminerRoy D. Frazier Assistant ExaminerThomas J. Holko Attorney, Agent, or Firm-Walter Spruegel 5 7 ABSTRACT Road marker having a base cup with a resilient cover diphragm near the top, and an elongated, substantially flat and rigid light reflector lens with a rigid base [56] References Cited mount in the middle of the diaphragm and below the UNITED STATES PATE TS top of the base cup, with the lens being normally in 1,778,110 /1930 Hartzler et a1 94/15 erect sp siti n n the diaphragm and extending 2,073.968 3/1937 Krebs...; 94/].5 above the top of the base cup, and the lens and dia- 2.779,240 H1957 Gaydos t X phragm yielding to a vehicle tire or plow blade passing 3.377.930 4/1968 Kone 94/15 over the marker, with the lens yielding in tilting fash- 3,392,639 7/1968 Heenan et a1 t 7. 94/15 i to a passing l blade. 3,570,377 3/1971 Gerber t 404/10 3.717.076 2/1973 Shields et a1 t. 404/1 1 5 Claims, 8 Drawing Figures /4 1 a4 16/ 155 1 f 46 i 4614/ 1 3" 1 J 7 4'0 66 2 54 68 55 52 I 6 6660 62.x I 26 LIGHT-REFLECTIVE ROAD MARKER thereon of a reflector system which is normally held by the diaphragm in operational light-reflecting position above the road level, and the diaphragm is adapted to yield momentarily for depression of the reflector system into the casing by a load passing over the marker. While in known road markers of this type the diaphragm will safely yield for harmless depression of the reflector system into the casing when vehicle tires ride on occasion over the marker, these reflector systems, and sometimes even their diaphragrns, will suffer damage and mostly destruction, on the very first passage, or at the most after a few passages. of a snow plowing blade over the markers. This holds true even in the case of markers whose reflecting systems are shaped to confront snow plowing blades with wedge-like surfaces which are designed harmlessly to be cammed out of the way by such passing blades, whereas in fact plow blades, heavy as they are and provided with sharp and notoriously destructive scraping edges and frequently plowing at speeds up to 30 miles per hour, have such severe impact and lacerating effect on these reflector systems that the latter will be destroyed more often than not. According to best available information, there are virtually no markers of this type installed in any public roads on which they would greatly contribute to traffic safety, and this is primarily due to the highly destructive effect snow plowing blades have on these markers which rules out their practical installation for any lasting performance.

It is among the objects of the present invention to provide road markers of this type which lend themselves to practical road installation for long-lasting satisfactory performance on any roads which bear vehicular traffic and which in winter are plowed for snow removal no matter how often.

It is another object of the present invention to provide a road marker of this type of which the diaphragm and the reflector system are arranged to yield to a passing vehicle tire and to a passing plow blade so that the diaphragm and reflector system will in'their yield undergo the least strain under the different impacts of a rolling vehicle tire, and of a sliding plow blade, on the reflector system.

It is a further object of the present invention to provide a road marker of this type of which the diaphragm and reflector system yield to a passing plow blade differently than to a passing vehicle tire to the aforementioned end of least straining the diaphragm and reflector system in either case, by arranging the diaphragm and reflector system so that they will give way to a passing vehicle tire in ready, more or less vertical, depression, and the reflector system will by a passing plow blade be safely tilted out of the way at entirely tolerable momentary stresses in the diaphragm at which its force reaction on the reflector system falls far short of enabling the passing plow blade to do any damage to the reflector system.

Another object of the present invention is to provide a road marker of this type of which the diaphragm and reflector system give way to a passing vehicle tire and to a passing plow blade in the aforementioned different fashion, by having the reflector system in the form of an elongated, substantially flat and rigid reflector lens with opposite faces and a longitudinal mounting base, and the resilient cover diaphragm in the marker casing has in the middle and below the casing top an embedded rigid holder in which the lens base is received and locked for holding the lens on the diaphragm in normally erect disposition thereon in which the same projects above the top of the marker casing. With this arrangement, and with the marker installed to have the reflector lens facing oncoming traffic, the lens and diaphragm will indeed yield quite readily to a passing vehicle tire in more or less vertical depression, and the lens, on being impacted at its exposed face by an oncoming plow blade, will by the latter be primarily tilted out of the way, with the plow blade having increasingly effective leverage for easily tilting the lens about an axis longitudinally, and midway of the width, of the rigid lens mount in the diaphragm within the marker casing, and this rigid lens mount serving additionally as rigid arms on opposite sides of its tilt axis for compelling the stresses in the diaphragm ensuing from tilting the lens to stretch and distort the diaphragm intoa crosssectional pattern roughly resembling S-shape in which the tilting lens clears most of the diaphragm for least impediment by the latter of its tilt response to the passing blade. Further, since the diaphragm and reflector lens will harmlessly give way to a passing vehicle tire in even fairly deep depression, and the lens will give way 1 to a passing plow blade by being simply tilted out of the way, the lens may project above the marker casing to an extent at which light reflected therefrom is visible to drivers at quite a large distance away from the marker. Also, with the reflector lens being tilted out of the way of a passing plow blade, and the diaphragm responding to the tilt of the lens as described, the stretched and distorted diaphragm will, immediately after passage of the plow blade, snap the lens back to its normal erect disposition with particular vigor and thereby shake off most, if not all, snow that may have stuck to the lens.

A further object of the present invention is to provide a road marker of this type of which the diaphragm is a molded part, and the aforementioned rigid lens holder is molded directly in the diaphragm and provided with a dovetail groove, while the base of the reflector lens is of dovetail section for its endwise slide into position in the dovetail groove in the holder and for its firm interlock therewith against lateral removal therefrom.

It is another object of the present invention to provide a road marker of this type in which the reflector lens is with its aforementioned base of dovetail section endwise slidable into the dovetail groove in the molded-in lens holder in the diaphragm for quick and convea lens in an installed road marker on such rare occasion when a lens becomes damaged.

It is a further object of the present invention to pro vide a road marker of this type of which the diaphragm is at its peripheral mount in the marker casing firmly locked to the latter against angular creep on the casing by vehicle tires passing over the marker, so that the light-reflecting face of the reflector lens will remain oriented with the road as it was oriented therewith at the road installation of the marker, i.e., will face oncoming traffic. To this end, the peripheral mounting surface on the marker casing, against which a peripheral margin of the diaphragm is customarily clamped by a top ring, is provided with a number of recesses into which project form-fitting finger formations on the diaphragm, and there is embedded in the peripheral mounting margin of the diaphragm a wire ring which is formed with intermediate loops that extend into the finger formations and stiffen the same so that they will never yield from the recesses into which they project and, instead, securely lock the diaphragm against angular creep on the marker casing from any cause whatever. Further, the embedded wire ring in the firmly clamped-down diaphragm on the marker casing contributes quite considerably toward preventing any substantial escape of entrapped air from the casing for the brief moments the same is being compressed by the yielding diaphragm on the passage of a load over the marker, so that after passage of the load this compressed air contributes quite considerably toward lively recovery of the diaphragm to its normal repose disposition.

Further objects and advantages will appear to those skilled in the art from the following, considered in conjunction with the accompanying drawings.

In the accompanying drawings, in which certain modes of carrying out the presentinvention are shown for illustrative purposes:

FIG. 1 is a top view of an installed road marker embodying the invention;

FIG. 2 is a section through the road marker taken substantially on the line 2-2 of FIG. 1;

FIG. 3 is another section through the road marker taken substantially on the line 3-3 of FIG. 2;

FIG. 4is a section through the road marker similar to that of FIG. 2, but showing certain prominent operating parts in a different position;

FIG. 5 is a fragmentary section through the road marker taken substantially on the line S5 of FIG. 4;

FIGS. 6 and 7 are fragmentary sections through the road marker similar to FIG. 2, but showing the marker in different operating conditions; and

FIG. 8 is a fragmentary section through prominent parts of the road marker and showing a step in their assembly.

Referring to the drawings, and more particularly to FIGS. 1 to 3 thereof, the reference numeral 10 designates a road marker which has as its major components a marker casing 12, a diaphragm l4, and a light reflector system 16.

The casing 12 is in this instance cup-shaped, having a bottom 18 and an annular rim 20 which define a chamber 22 that is open atthe top 24 of the rim. The casing 12 is customarily embedded in a road bed 26, and is in this instance flush at the rim top 24 with the road surface S.

The diaphragm 14 is resilient, and is preferably molded of any suitable tough elastomer, such as neoprene, for example. The diaphragm 14, which in this instance is of general disc shape, extends across the casing rim 20 to close the chamber 22, and has a peripheral margin 28 with which it is anchored to the casing. To the end of anchoring the diaphragm 14 to the casing 12, the latter is in the top of its rim 20 provided with an annular recess 30 to provide a ring-shaped seat 32 for the peripheral diaphragm margin 28, with this seat 32 having in this instance an inner raised lip formation 34 of exemplary curved section. The peripheral diaphragm margin 28 is held firmly clamped against the seat 32 by a retainer ring 36 which is mounted, preferably removably, in the casing 12. To the end of thus mounting the retainer ring 36 in the casing 12, the former is in this instance provided with integral side tongues 38 which are received in bayonet-type slots 40 in the annular recess 30, with the side tongues 38 on the retainer ring and the lock branches 42 of these bayonet slots having a slight pitch for their wedge-like cooperation in firmly clamping the retainer ring against the peripheral diaphragm margin 28. The raised lip formation 34 on the diaphragm seat 32 serves to lock the peripheral diaphragm margin 28 against any give on its seat 32 under operational stretch of the diaphragm.

The light reflector system 16 has as its major components an elongated, substantially flat and rigid reflector lens 46 with opposite reflector faces 48, and a lens mount 50 on the diaphragm 14. More particularly, the lens 46 provides in this instance a grid 52 having opposite light-reflective faces 54, and a protective body 56 of a suitable rigid transparent plastic in which the grid 52 is embedded and which provides the lens faces 48 through which light passes to and from the reflective grid faces 54.

The lens mount 50 provides in this instance a longitudinal mounting base 58 on the reflector lens 46 and a support 60 on the diaphragm 14 which is below the easing top 24 and to which the lens base 58 is firmly anchored. More particularly, the lens base 58 is in this instance formed as an integral part of the rigid lens body 56, with the lens base 58 being, for its support on and anchorage to the diaphragm 14, received in, and locked to, a middle part 62 of the diaphragm 14 below the casing top 24, as by being molded directly in this diaphragm part 62, for example. It is preferred, however, to provide in this middle diaphragm part 62 a rigid lens holder 64 in which the lens base 58 is re ceived and firmly locked, with the lens holder 64 being molded directly in the middle diaphragm part 62 and being in the preferred form of a channel of dovetail groove configuration, and the lens base 58 being, accordingly, of dovetail section for its filled reception in the dovetail groove in the channel 64. The lens-holding channel 64 may be of any rigid material, and is preferably of metal for its firm and secure bond with the diaphragm material on being molded directly in the diaphragm. The channel 64 in the middle diaphragm part 62 thus firmly holds the lens base 58, and with it the reflector lens 46, properly oriented with respect to the diaphragm 14, with the reflector lens 46 normally assuming a position in which its opposite faces 48 stand erect on the diaphragm 14 (FIG. 2).

The middle diaphragm part 62, in which the channel 64 is provided, is preferably a longitudinal rib formation 66 on the diaphragm which is of adequate body,

i.e., thickness and also width, for firm embedment of the molded-in channel 64 in, and its secure lock to, this rib formation so that the latter will act as an integral part of the channel 64 under all conditions, including operational depression and tilting of this channel as described hereinafter. Also for reasons described hereinafter, the diaphragm 14 on opposite sides of the rib formation 66, and also around the ends of the rib formation, is of less thickness than this rib-formation as indicated at 68 and 70 (FIGS. 1 to 3).

The reflector lens 46 is of a height normally to project above the casing top 24 so as to reflect light from an oncoming vehicle which is visible to the driver of the vehicle, provided, of course, that the road marker is properly installed in the road bed with its reflector lens facing oncoming traffic.

In operation of the installed road marker, it is inevitable that a vehicle will occasionally pass with at least one tire over the marker, and plow blades of heavy snowremoval trucks will certainly pass over the marker when the road is being plowed. While the impacts on the reflector lens by a vehicle wheel and by a plow blade passing over the marker are diflerent at least in kind, one being mostly rolling impact by a wheel and the other being collision impact by a plow blade, either kind of impact may be sufficiently severe to damage the plastic lens body 56. To avoid such possible damage to this plastic lens body, the same has suitably secured to its opposite side edges and to its top edge a U-shaped protective frame or guard 72 of exemplary channel shape and made of any suitable tough material which will not break under even the most severe impacts of this kind. v

The reflector lens 46 is with its base 58 applied to the channel 64 conveniently and advantageously after the latter is molded in the diaphragm 14 and before the diaphragm is applied to the marker casing 12. To this end, the channel 64 is in its mold-in in the diaphragm 12 embedded with at least its bottom and side surfaces in the diaphragm elastomer, but its dovetail groove is exposed for reception of the lens base 58 on endwise slide-in of the latter, and provisions are made in the diaphragm which permit such endwise slide of the lens base into the dovetail groove in the molded-in channel 64. Thus, while both ends of the dovetail groove in the channel 64 are closed by adjacent wall portions 74 of the rib formation 66 on the diaphragm (FIG. 3), one of these wall portions 74 is unconnected with the adjacent channel end 76, and is formed by a part 78 of the rib formation 66 which at and near this channel end is also unconnected with the channel and with the rest of the rib formation 66 in such manner that the diaphragm at and near the part 78 thereof may temporarily be resiliently distorted like or similarly as shown at 80 in 'FIG. 8, in order to retract the wall portion 74 thereat from the adjacent channel end for endwise introduction of the lens base 58 into the dovetail groove in the channel 64. The diaphragm 14 may readily be provided with such an unconnected part 78 by restoring to plugs or separators which are well known in molding technique, and which are properly placed in the mold in which the diaphragm is molded and which also holds the channel 64 for its direct molding in thediaphragm. Temporary resilient distortion of the diaphragm like or similarly as shown in FIG. 8 is done manually, and is facilitated by the use of a special praying tool (not shown). Of course, in order to lend itself to this rather severe distortion, the diaphragm 14 must obviously be removed from the marker casing 12, and once the lens base 58 is slid into place in the channel 64 in this fashion and the diaphragm released, the distorted diaphragm part will of its own accord spring back to its normal disposition in the diaphragm (FIG. 3). This mode of introducing the lens base 58 in the molded-in channel M is further advantageous in that it permits replacement in any road marker at its installed location of a reflector lens when its lens is damaged on rare occasion. To thus replace a lens, the diaphragm is temporarily removed from the installed marker casing on first removing the retainer ring 36. To the end of facile removal of the retainer ring 36, the same is provided with a number of holes 82 to which to apply a suitable tool (not shown) which may also be used to advantage in remounting the retainer ring.

To lock the clamped-on diaphragm 14 to the installed casing 12 against angular creep thereon under passing loads so as to avoid displacement of the reflector lens from its proper traffic-facing disposition, the diaphragm 14 is on its peripheral mounting margin 28 provided with a plurality of integral finger formations 84 which project into, and are received with a form-fit in, recesses 86 in the diaphragm seat 32 in the casing,

and in this instance in its raised lip formation 34 (FIGS.

1 and 2). These finger formations 84 on the diaphragm are made quite rigid by therein extending loop formations 88 on a wire ring 90 which is molded directly in the peripheral mounting margin 28 of the diaphragm.

Thus, these loop formations 88 so stiffen and otherwise reenforce the finger formations 84 that the latter will never yield from the recesses 86 or be sheared off under any load forces. Actual road markers under test have also demonstrated that the molded-in wire ring 90 with its loop extensions 88 into the finger formations 84 on the clamped-on diaphragm contributes considerably toward preventing any substantial escape of air from the closed casing chamber 22 during the brief intervals of operational yield of the diaphragm under a load passing over the marker and ensuing compression of this air, so that after passage of the load this compressed air will lend snap to the recovery of the diaphragrn to its normal disposition, so much so that no diaphragm-return spring is required in the casing chamber 22. Of course, such a diaphragm-return spring may be used, if desired, and such aspring is shown at 92 in FIGS. 3 and 4, in the exemplary form of a resiliently depressible plunger, but such a spring is omitted in FIG. 2 since it is not an imperative element as indicated.

Assuming now that a vehicle tire rides over the installed road marker more or less in normal traffic direction, or even at wider deviation therefrom as may happen on occasion, the reflector lens and diaphragm will yield to the passing tire in downward depression which most likely is more or less vertical depression (FIGS. 4 and 5). With the impact of such a passing tire on the reflector lens being rolling impact, or mostly so, the reflector lens will easily withstand the impact, and the diaphragm will not only yield quite readily to the passing tire, but its ensuing momentary stretch is far below tear proportions. Nevertheless, and as appears from FIGS. 4 and 5, recovery of the diaphragm to its normal disposition after passage of the tire will be quite lively, so much so that dirt or other foreign matter on top of the diaphragm will most likely be thrown off.

Let it now be assumed that a snow-plowing truck passes with its plow blade b over the installed road marker (FIGS. 6 and 7). Such a truck will proceed in general traflic direction so that its plow blade, though usually somewhat slanted toward the right side of the road on which to pile the snow, will impact the reflector lens more or less face-on in its normal erect disposition (FIG. 2). Thus, with the reflector lens then projecting above the casing top 24 and, hence, above the road surface S, and with the rigid lens mount on the diaphragm being below the casing top and road surface, the reflector lens will yield to the impacting plow blade in least resisting manner which is mostly a tilting response of the reflector lens about a longitudinal axis x of its rigid base mount on the diaphragm (FIGS. 2, 6 and 7). Thus, with the passing plow blade b having at its initial impact with the reflector lens effective leverage I on the tilt axis x of the lens (FIG. 2), the lens will follow the path of least resistance in yielding to the plow blade in the mentioned tilt fashion, and the lens will neither be crushed nor sheared by the impact of the blade b even though such plow blades are customarily quite heavy and have sharp and potentially quite destructive scraping edges. The reflector lens will increasingly be tilted out of the way of the passing plow blade b (FIGS. 6 and 7 and while the diaphragm in its ensuing operational stretch and also distortion response will increasingly resist such increasing tilting of the reflector lens, the effective leverage of the passing plow blade to the tilt axis x of the lens also increases so that the progressive tilt of the reflector lens out of the way of the passing plow blade proceeds quite smoothly all the way. Further, with the rigid lens holder 64 of exemplary channel form in the rib formation 66 on the diaphragm being of a definite width which in this instance is greater than the width w of the reflector lens across its opposite faces 48 (FIG. 2), and with this rigid lens holder 64 imparting rigidity to the rib formation 66 on the diaphragm over most, if not all, of its width, this rib formation 66 serves as rigid arms a on opposite sides of the tilt axis x of the lens, with these arms a serving, on the tilt of the lens out of the way of the passing plow blade, to compel most of the diaphragm to yield in a pattern which cross-sectionally roughly resembles S- shape (FIGS. 6 and 7) and in which the tilting lens clears most of the diaphragm for least impediment by the latter of its tilt response to the passing plow blade. Each of the diaphragm portions 68 of reduced thickness on opposite sides of the rib formation 66 extends at least over the expanse of the reflector lens in its fully tilted condition (FIG. 7), so that these diaphragm portions will readily respond to the tilting lens in resilient stretch and also some resilient distortion which fall far short of overstraining the diaphragm. Nevertheless, operational stretch and distortion of the diaphragm under a passing plow blade (FIG. 7) are quite conducive to snapping the diaphragm and reflector lens thereon quite forcefully back to normal condition (FIG. 2) once the plow blade has passed, with such powerful snap-back of the diaphragm and lens throwing off most, if not all, snow that may stick thereto.

While the reflector lens wiil yield to a passing plow blade by tilting out of the way, as described, the reflector lens will in its yield undergo some more or less slight bodily shift different from and in addition to its tilt, owing to the resilient nature of the diaphragm which compels it to yield to the tilting lens in least resisting manner which, while mostly predictable, is not entirely predictable. Also, while in the diaphragm of the exemplary section shown in FIG. 2 the rigid lens mount thereon, and also the diaphragm of smaller thickness flanking this lens mount, are below the road surface to the indicated extent, they may, if desired, be arranged closer to the road surface, though below the latter, without appreciably affecting the described performance of the reflector blade under a passing vehicle tire or plow blade. Further, since the diaphragm and reflector lens will readily give way to a passing vehicle tire in depression which is far from damaging the diaphragm even in fairly deep depression, and the lens will give way to a plow blade by simply being tilted out of the way, the lens may project above the road surface to an extent at which light reflected therefrom is visible to drivers at quite a large distance away from the marker.

What is claimed is:

1. A road marker, providinga cup-like casing having a bottom and being open at the top; a molded resilient diaphragm peripherally anchored to the casing and extending across the casing to close the same; an elongated, substantially flat and rigid reflector lens with opposite faces; and a lens mount in said diaphragm, providing a rigid longitudinal holder permanently molded in said diaphragm substantially in the middle thereof and below said casing top whereby said holder imparts its rigidity to a portion of the diaphragm surrounding said holder, and a rigid longitudinal mounting base on and integral with said lens, with said base being received in and locked to said holder for holding said lens on said diaphragm with said faces in normally erect disposition thereon, and said lens being of a height normally to project with said faces above said casing top, said diaphragm portion, holder and lens including its locked base in said holder together forming a rigid unit tilting about a longitudinal axis of said holder on impact with one of said lens faces of a plow blade on its pass over said casing top, said diaphragm being on opposite sides of said portion thereof of adequate expanse to yield to the lens in its tilt out of the way of a passing plow blade, and said diaphragm being sufficiently spaced from said casing bottom to yield on the ride of a vehicle tire over said casing top and lens.

2. A road marker as in claim 1, in which said diaphragm portion is an integral longitudinal rib formation of given thickness on said diaphragm, and said diaphragm is of less than said given thickness over said expanse thereof on opposite sides of said diaphragm portion.

3. A road marker as in claim 2, in which said holder and lens base are of greater width than that of the lens across said faces and project beyond both of said faces, so that said diaphragm will over said expanse on one side of said diaphragm portion be deflected downwardly toward said casing bottom on the tilt of said lens to said one side of said diaphragm portion out of the way of a passing plow blade.

4. A road marker as in claim 3, in which said holder is a channel with a dovetail groove, and said lens base is of dovetail section and fittedly received in said groove.

5. A road marker as in claim 1, in which said casing has an annular rim open at said casing top, with said rim having below said top a ring-like diaphragm seat with spaced recesses, said diaphragm is in form of a disc, and there is provided a ring secured to said rim for ses, and said diaphragm having in said peripheral marclamping a peripheral diaphragm margin to said seat, gin a molded-in wire ring with spaced loop formations with said peripheral diaphragm margin having integral extending into said finger formations. finger projections form-fittedly received in said reces-

Claims

1. A road marker, providing a cup-like casing having a bottom and being open at the top; a molded resilient diaphragm peripherally anchored to the casing and extending across the casing to close the same; an elongated, substantially flat and rigid reflector lens with opposite faces; and a lens mount in said diaphragm, providing a rigid longitudinal holder permanently molded in said diaphragm substantially in the middle thereof and below said casing top whereby said holder imparts its rigidity to a portion of the diaphragm surrounding said holder, and a rigid longitudinal mounting base on and integral with said lens, with said base being received in and locked to said holder for holding said lens on said diaphragm with said faces in normally erect disposition thereon, and said lens being of a height normally to project with said faces above said casing top, said diaphragm portion, holder and lens including its locked base in said holder together forming a rigid unit tilting about a longitudinal axis of said holder on impact with one of said lens faces of a plow blade on its pass over said casing top, said diaphragm being on opposite sides of said portion thereof of adequate expanse to yield to the lens in its tilt out of the way of a passing plow blade, and said diaphragm being sufficiently spaced from said casing bottom to yield on the ride of a vehicle tire over said casing top and lens.

5. A road marker as in claim 1, in which said casing has an annular rim open at said casing top, with said rim having below said top a ring-like diaphragm seat with spaced recesses, said diaphragm is in form of a disc, and there is provided a ring secured to said rim for clamping a peripheral diaphragm margin to said seat, with said peripheral diaphragm margin having integral finger projections form-fittedly received in said recesses, and said diaphragm having in said peripheral margin a molded-in wire ring with spaced loop formations extending into said finger formations.