CA2158908A1 - Flexible raised pavement marker, mounting device and method - Google Patents

Abstract

A flexible, raised snowplowable pavement marker having a top portion that readily deforms downwardly into a base portion when impacted by vehicular traffic or a snowplow blade. Markers installed in a cavity bored in pavement are anchored in place with grouts or alternatively within an annular ring mounting device. The marker body may be black in color to take advantage of solar activity in improving marker performance and longevity and may be vented to atmosphere to facilitate the downward deflection of the top portion of the pavement marker. A retroreflective sheeting is affixed to the marker so that the marker is highly visible to motor vehicle drivers at nighttime.

Description

89~8 FLEXIBLE RAISeD PAVEMeNT ~ARKER, I.J(1..11N~: DEVICE AND METHOD
TECHNICAL FIELD
The present invenl: lon pertalns to a f lexlble ralsed ~dV~ t marker that la readlly def lected downwardly upon lmpact, such as by vehlculalr t raf f lc or a snowplow blade . It also relates to a devlce thl~t can be used to mount the marker, or other ob~ects, ln a ~l~v'e -~t borehole and relates to ongolng malntenance of ob~ects contalned wlthln the devlce.
PIAI r~ NI~ OF THE INVENTION
Ralsed p~v, t m~rkers have evolved over the past slxty years and serve to dellneate areas such as trafflc lanes on p~v~ t surfaces. Most pavement markers lnclude some form of reflector to lmprove motorlsts' nlghttlme vlsual perceptlon. The beneflts of ralsed pdV~ t markers lnclude lmproved wet reflectlvlty whereln the markers dellneate areas when preclpltatlon on pavement surfaces reflects llght from vehlcle headllghts obscurlng marklngs palnted on the pavement.
Another benef lt of ralsed ~av~ - marklngs 18 improved nlghttlme vlslbillty over long dlstances. Thls contrlbutes to lower motorlst vlsual stress, thus lower fatlgue, yleldlng lmproved sa~ety for nlghttlme drlvlng.
Ralsed pavement rlarkers have been lnstalled at the p~v, surface uslng a varlety of flxatlon means lncludlng metal plns, nalls, screws clr alternatlvely an adheslve means.
Such markers are shown ln ~I.S. patents 1,802,940 (Cornellus), 4,088,416 (Taylor), and 4,717,281 (8hepherd et al.). The use of metal poses a threat because dlslodgement of such components may result ln lncreased hazards for vehlcles.

~ 21 ~3~U8 Metal pins and screws, once dislodged, could flnd their way into vehicle tires or they could, as the markers themselves, become pro~ectiles on roadways when acted upon by vehicular traffic, particularly at high speeds. One sure method of dislodgement for these types of markers can be from the action of snowplows.
Rai6ed ~v ~ Dlarker have been devised that address the action of snowE~lows. Such raised, snowplowable p~ r ?I markers usually requlre boring or cutting a cavity within the ~v, --lt surface for fixation means. In general, raised snowplowable ~CIV~ L markers appear as three broad types in their constructiorl, a) rigid, non-articulated, non-deformable units that withstand substantial lmpact forces of snowplow blades at high speeds as shown ln U.8. pat:ents 4,147,447 (Heenan et al.), 4,577,992 (Jefferies) and ~L,634,310 (Clarke). Although somewhat simpllstic in their contruction, these units typically employ cast meta:L bases to withstand high lmpact forces lmparted to them by snowplows. Portlons of the markers are dlsposed above the p~v -`lt surface and deflect snowplow blades off the p~v~ sul-face to protect the reflector mounted on the marker. Retroreflectors mounted on these unlts also are typically rigid ill their construction. These markers although useful, present several difficulties for roadway maintenance operations. PLowblades and the vehicles to which they are attached can suff~?r considerable fatigue and damage as a result of the plowbla~e striking the cast metal surfaces at high speeds. The cast metal ramps on this type of P~VI 1,

2~a8~8 marker def lect plowblades upwards off the p~ nt surface .
Thls can leave snow and lce on the pavement surface ln the area lmmedlately about and beyond the marker lmpact point.
The plowblades upon returnlng to the road surface also may damage the road surface upon lmpact and can damage or destroy pelvl ~ markings resultln~g ln lncreased pdV~ t malntenance costs, 6nowplow operators have e~perlenced nausea from prolonged plowlng operat lolns on roadways employlng such markers as the lmpact energy and loud nolse transmltted to the plow vehlcle ~nhRn~-. P operator stress levels. At hlghway speeds, plow lmpact wlth m~rkers can occur as often as once a second. Plowlng ln snowstorm condltlons, ln trafflc, at hlgh speed for many hours 18 stressful enough wlthout thls a~dltional perslstent distractlon.
b) artlculated unlts that are mechanlcal or employ compresslble components to allow marker sectlons that are ralsed above the pavement l,o move or retract to survlve lmpacts from snowplows and vehlcle tlres. Mechanlcal unlts such as shown ln U.S. patents 4,140,418 (Holley) and 4,848,958 (6heldon) employ metal components that ultlmately may deterlorate from the effect:s of salt and sand materlals used on pavements durlng snow alld lclng condltlons. Although these types of marker are unllke~y to lmpede pavement plowlng operatlons, they re~ulre s~lbstantlal open cavltle8 ln ~ ê ont t o ope rat e .
The cavlt les are problemat lc because they are llkely to trap debrls. Frozen wat:er wlthln the cavltles may lmpede proper functlon of the unlts and lead to thelr destructlon by o~ l snowplows. U.S. patent 5,302,048 ~Paulos et al. ) dlscloses a ~,~v---- ' marker that can hl~ve several of its components replaced, however, the mar!cer employs elaborate mechanlcal components to provlde such, and the impact energy requlred to deflect the marker top sec~lon 18 belleved to be essentlally of the same magnltude as tlnat experlenced wlth the rlgld, non-deformable unlts thus pres~ntlng many of the road malntenance concerns assoclated wlth tlhe rlgld unlts. Further, malntenance of the marker l~nay be dllfflcult.
c) reslllent, deformable unlts, that employ cavltles ln the ~a-- t~ sltuate and anchor the markers.
Most lnvolve a body structure that contalns a reflector--although U.8. Patents 3,890,054 (o~connor) and 4,815,818 (Thomas) dlsclose arrays of reslllent, flngerllke pro~ectlons that are ref lectorl~ed. Doformable, reslllent body types are dlsclosed ln U.8. patents 4,2g7,051 (Roblnson), 4,659,248 (Flanagan) and 5,06g,577 (~Surphy). Flanagan dlscloses a unlt that resldes totally below the pavement surface and would llkely survlve the actlon of snowplows but llke the mechanlcal unlts of Holley and ~heldon, a substantlal p~v, --' cavlty 18 requlred that may f 111 wlth debrls or water, renderlng the retroreflector lmpercelvable to vehlcular trafflc. Roblnson and Murphy and U.8. patent 3,850,536 (Kone) employ a cavlty cut lnto the p~v.-- ' that 18 lntended to accommodate the upper portlon of the marker body when deformed by vehlcular trafflc and snowplow blades. Kone deslres alr, trapped wlthln the marker cavlty, to asslst ln proper operatlon of the marker. Roblnson suggests that wlth a sultable grout, the 90~
lnternal cavlty 18 airtlght and asslsts the marker ln returnlng to lts normal sh~pe and attltude followlng deformatlon. The markers l~re anchored ln the cavltles ln the G'v~ L by capturlng a skirt and flange portion of the marker body uslng sultable grouts. As the side walls or sklrt portlon of the marker bodles are lntegrally molded wlth the flexlble top portlons, there 18 potentlal for slde wall deformatlon upon snowplow impact. Robln30n makes provlslons to strengthen or stlffen tlhls portlon of the marker body to prevent damage to the devlce upon plow lmpact.
Most snowplowabl~ p~v~ - L markers ln use today are rlgld, non-deformable cast metal base type markers contalnlng rlgld cube corner retroref lectors that are adheslvely bonded (usually epoxy) to the metal base. ~uch markers, as prevlously descrlbed and clted, are lnstalled by cuttlng or borlng a sultable cavlty ln the ~c~v~ to accept the lower portlon of the metal base and then flxatlng the unlts ln the cavlty wlth a sultable epoxy, cement or slmllar rlgld grout.
8ecause of road closure tlme llmltatlons, these grouts are usually fast settlng/rapld cure type materlals. Aslde from any lntended cavltles wlthln the marker bodles themselves, the entlre cavlty cut ln the ~v -nt. typlcally ls fllled wlth the grout and the marker body materlal leavlng no volds wlthln the pavement .
Glven that retroreflectors on ralsed snowplowable ~v. ' markers are exposed to trafflc and studded tlres, tlre chalns, snowplows, road chemlcals, and weather, they do not last forever. Reasonable llfetlmes are on the order of 2 6055~ -48Zl ~8908 to 3 years. Efflclent replacement of the retroreflectors poses problems ln that lf a retroreflector 18 easlly removed for replacement, lt 18 113cely to become dlslodged on lmpact by vehlcular trafflc or snowl?lows. Few publlshed documents dlsclose detalls on malntenance or refurblshlng methods, or go on to address the lnevltal~le requlrements when pavement resurfaclng 18 requlred.
~UMMARY OF THE INVENTION
The present lnv~ntlon provldes a new, flexlble, ralsed, snowplowable pavement marker . The lnvent lon also relates to a devlce that can be used to mount the marker, or other useful ob~ects, ln a pavement borehole. The use of comblnatlons of component~i enables a marker system to be tal lored f or varlous appl icat lons .
The marker preferably 18 molded as a slngle entlty contalnlng several reglonEi varylng ln structure, cross sectlon and functlon and all actlng ln concert to assure survlvablllty of the marker over a usefl~l llfetlme, partlculary ln regard to survlvlng repeated lmpactEi from snowplows at hlgh speed under ext reme condlt lons .
Accordlng to an aspect o~ the lnvent lon, there 18 provlded a ralsed unldlrectional paVement marker for lnstallatlon ln a pavement: borehole. The marker comprlses a body member havlng a ba3e portion and a generally dome-shaped top portlon. The top portlon has a flrst stlffened region and a second flex~ble reglon, where the flrst reglon has a surface for receiving a retroreflective materlal. The term "st lffened" is used herelrl to mean the f lrst reglon rlgld 60~57 -4821 2i ~9~8 relatlve to the second reglon, and the term "flexlble" 18 used hereln to mean the second reglon ln general ls less rlgld than the flrst reglon. The sec~ond reglon's flexlble nature asslsts ln allowlng the top portlo~ to be deflected downward lnto the base when a force 18 recel~ed on the f lrst reglon of the top portlon. A thlrd flexlble reglon, on the marker body lnterlor, acts as a hlnge Eor the entlre top portlon. A
fourth flexlble reglon, ln,~luded ln the upper one thlrd of the base portlon, adds lateral flexlblllty to the top portlon.
The pavement marker 18 sufElclently reslllent to enable the top portlon to return to lts generally dome-shaped conflguratlon upon release of the force from the flrst reglon.
The resillency 18 furnlshed ln part by the second reglon, Whose flexlblllty allows the top portlon to "pop" back lnto lts dome-shaped conf lgurat lon .
The top port lon ~f the kJ~V~ - L marker, when lnstalled, protrudes above the paVement surface and 18 exposed to potentlal detrimental affects Erom snowplow blades and vehicle tires, in combination wlth salt and sand, and weather elements lncludlng ultra vlolet solar radlatlon, preclpltation ln many forms, and temperature extremes from as low as mlnus 40 degrees to as hlgh as o~e hundred and slxty degrees fahrenhelt. These temperature extremes are lmportant ln that they affect the char~cterlstlcs of the pavement marker body materlal. A materlal that has proved useful ln appllcatlon to thls lnventlon 18 thermoplastlc polyurethane, partlcularly of the polyether type and havlng a glass transltlon temperature (Tg) of mlnus forty degree~ or lower. The thermoplastlc 60~57-4821 polyurethane may contaln uLtravlolet lnhlblters to reduce the degradatlon effects of sol~lr exposure.
In the top portlon, the flrst stlffened re~lon 18 located ln the dlrectlon o~ snowplow lmpact. Thls stlff reglon lncludes mountlng mt~ans and preferably a protectlon means for the reflector. '~he stlffened reglon may be achleved by thlck cross sectlon of l:he flexlble marker materlal or alternatlvely by "corlng" l;hls reglon. Corlng 18 a term used to descrlbe the lncluslon ~f rlb structure that stlffens and strengthens an area effectively without addlng proportlonately to the bulk of the component. Mlnlmi~lng bulk ln the pavement marker flrst reglon is deslrable as hlgh lnertla ln thls flrst region 18 detrlmental to sllrvlval of the pavement marker when lt 18 expected to 1 ~11Ately move and lmmedlately transmit plow lmpact energy to effect other responses ln other reglons of the m~rker top portlon. The collapslng actlon response of the marker body to lmpact ]nay be requlred to happen ln as llttle as two one-thoUsandths of ~ second. In thls regard, lt should be noted that the slhape of the flr3t reglon preferably 15 suhstantlally coslnusoldal ln cross-sectlon (when vlewed from a plane blsectlng the flrst reglon) whlch allows snowplow lmpact energy to transfer to the marker ln a more gradual fashlon than would otherwl3e occur wlth other shapes such as convex domes of prlor art ~markers. Thls gradual bulld of energy 18 effected by the lnltlal low tangentlal approach angle between the plowblade and the marker body surface. Thls mlnlmlses potentlal for step style lmpact energy whlch could cause the plowblade to penetrate the reslllent marker body ~ 8~08 material, resultlng ln cuti3, tears or posslble removal of the mQrker from lts mountlng. Thls actlon ls alded by the thlnned upper base portlon whlch allows lateral r ~v~ t, of the marker top sectlon upon lnltlal lmpact of the marker by a snow plow.
The response tlme of the marker ls effectlvely lncreased by the lateral rn v. ' and mily add as much as one-half of one thousandth of a second to the tlme re~ulred for the deformatlon of top sectlon to commence. As the plowblade progresses across the mark~3r body f lrst reglon, the f lrst reglon 18 forced downward ~3nd preferably malntalns a low tangent angle between the plowblade and the marker body surface. The low tangent ~ngle can mlnlmlze energy transfer f rom the plowblade to the ]narker body . Hlnglng act lon and overall hlgh compllance of the marker materlal and shape preferably 18 such that mll~lmum energy 18 requlred to depress the marker top portlon allowlng the plowblade to pass over the marker wlthout damage to the marker. ~ess efflclent deslgns ext ract hlgher energy f rom the plowblade whlch must be dlsslpated ln the marker amd generally result ln marker deterlorat lon or damage .
The f lrst reglon when hlnglng downwardly under the lnfluence of lmpact, transfers energy and acts upon the second reglon. The pavement marker ls mounted on a roadway so that the second reglon 18 dlsposed away from the dlrectlon of plow l~npact. The second reglon preferably has a symmetrlcal concave sectlon ln lts center whlch predlsposes the second reglon to def lect downwards when acted upon by the f lrst reglon. The second reglon preferably ls effectlvely hlnged to g _ 9~
the first reglon ln the transltlon area between the reglons where the stlffer reglon meets thls more compllant reglon.
A thlrd reglon ~ihlch 18 more f lexlble than the second reglon, e.g., by belng thinner, may be provlded at the lnterface between the mar~er top reglon and the lower sklrt reglon, preferably at or }~elow the pavement level when the marker 18 lnstalled. More speclf lcally, the thlrd reglon preferably 18 located abollt the lnner perlphery of the marker body to effectlvely perfo].m a hlnge functlon for both the f lrst and second reglons ~hen the marker 18 sub~ected to lmpact deformatlon, allowlng these reglons to deflect withln the cavlty bounded by the cyllndrlcal base portlon as the plowblade passes over the marker. A fourth f lexlble reglon 18 located about the upper olle thlrd of the marker sldewall base portlon. This reglon 18 more flexlble than the lower sldewall base port lon by belng forlned wlth a reduced thlckness ln comparlson, the flexlble upper sldewall sectlon belng approxlmately one half the thlckness of the lower sldewall sectlon and approxlmately equal to the thlckness of the flexlble second reglon. 'rhls fourth flexlble reglon provldes for lateral -- v~ L of tlhe marker dome upon plow lmpact.
Lateral movement of the dome decreases the ~ y of the f lrst and second reglons to respond to plow lmpact energy thus lncreaslng the responslVe tlme of these reglons and thus impartlng greater ablllty of the marker dome to survive lmpact. The thlnned upper sldewall re~lon 18 an effectlve lateral hlnge for the marker dome.
Accordlng to another aspect of the lnvent lon, there 8~08 , 1B provlded a devlce for lnountlng an ob~ect ln a pavement borehole. The devlce comprises an annular wall of flexlble synthetlc materlal having an lnner surface and an outer surface. The lnner surfa,ce ls adapted to frlctlonally engage the ob~ect, and the outer surface has a plurallty of annular rlbs adapted to engage the pdV~ 1 wlthln the borehole.
Accordlng to an~ther aspect of the lnventlon, there 18 provlded a ral3ed pClVI - L marker that comprlses a body member havlng a base portlon and a generally dome-shaped top portlon. The top portlon has a hole to vent the marker to the atmosphere. The top portlon can be deflected downward lnto the base portlon upon recelvlng a force thereon. The pa marker 18 Bufficiently reBilient to enable the top portion to return to lts generally dome-shaped conflguratlon upon release of the force.
Accordlng to another aspect of the lnventlon there 1B provlded a pavement marker formed of reslllent materlal comprlslng black polyurethane.
The marker may be mounted ln a pavement borehole uslng the mountlng devlce. Other useful ob~ects also could be mounted uslng the mountlng devlce of the lnventlon.
Flexible metalllsed retroreflector material 1B
preferably afflxed to the marker wlth a unlslue, flexlble, weatherable adheslve system.
The ralsed ~v~ ~ marker of the lnventlon may be installed in a cavity that has been bored in the pavement.
The top section of the marker is dlmensloned, shaped, and hinged, such that lt deforms and deflects easily into the ~1~8~108 cavlty wnen impacted by vehlcular traffic or a snowplow blade.
The marker body 18 preferably vented to atmosphere. Thls enables the marker's top E)ortlon to rapidly deflect lnto the base portlon when impactecl by a snowplow. Ventlng also allows molsture collected wlthln the marker cavlty to evaporate.
Ventlng also may ease the marker lnstalllng procedure by ellmlnatlng pressure effects of alr wlthln the marker cavity.
Markers may be lnstalled i.n the pdV~ -~lt cavlty wlth grout materlals or alternat lvel~ wlthln a mount lng devlce that has been lnstalled ln the cavi.ty. The marker body preferably lncludes a perlpheral sklrt comprlslng a base portlon havlng an lntegral flange for mountlng. The lower two thlrds of the perlpheral skirt sectlon Dlay also contaln a rellef area to reglster the marker body 3n a predetermlned orlentatlon wlth respect to a mountlng devi,ce, wlth such mountlng deviLce contalnlng a matlng lnverse rellef. Thls reglstratlon of marker body and mountlng devlce ensures proper lnstallatlon of the mount~lng devlce relatlve to trafflc dlrectlon and also prevents rotatlon of the marker body wlthln the mountlng devlce. Rotatlonal forces are exerted upon the marker body wlthln the mountlng devlce. Rotatlonal forces are exerted upon the marker body by t~le typlcally obllque lmpact angle oi plowblades. When grout ls used to lnstall a marker body contalnlng such reglstratlon rellef ln lts sklrt sectlon, the matlng reglstratlon rellef 18 formed ln the grout.
A mountlng devlce iLn the form of an annular rlng may be provlded as an alternatlve to mountlng the marker ln the pavement uslng a rlgld or flexlble grout. The mountlng devlce ., ~ ~lsa,sos can perform multiple functlonE, includlng provldlng ease of mountlng for the marker wlthln the p~v, L cavlty at the proper helght, provldlng ventlng capablllty to the marker lnterlor, provldlng ea~y, fa~t replacement of marker bodles when refurblshlng 18 requlred, and counteractlng asphalt creep. The mountlng devlce contalns a plurallty of flexlble rlbs about lts perlphery that deform and grlp the inner surface of the pav- r t cavlty. Under certaln condltions a sultable grout may be used to provide addltlonal anchorage of the mountlng devlce to the pavement. A preferred materlal for the mount lng devlce 18 a hlgh denslty polyethylene that has conslderable cold temperature f leslblllty allowlng the mountlng devlce and marker to conform to the pClV~ - L
topography. Cold lmpact strength 18 another feature of thls material. A rlng seal, manufactured from flexlble, closed-cell foam materlal, such as polyethylene foam wlth an ~VA
(Ethyl Vlnyl Acetate) addltlve for flexlblllty, also may be used. The seal compresses when the mountlng devlce 18 lnstalled above lt. The seal can prevent molsture from collectlng beneath the p~v, L marker, whlch could freeze and force the rlng upwards.
Novel methods and components are employed to lnstall the marker ln the pav, ~I' . In the case of anchorlng the marker ln the ~av, -- wlth the mountlng devlce, the typlcally hydraullc drlven drlll equl - , used to form the borehole ln the pClV L, 18 used, ln con~unctlon wlth an lnsertlon flxture, to drlve the preassembled comblnatlon of marker and mountlng devlce lnto the borehole. The drlll blt contalns -- 1~ --;

~ ~a8908 unlque "kerf " cuttlng components to ensure markers are lnstalled at proper operat:ing depth ln the pdV~- L.. In the Case of markers mounted lrl the pavement wlth grout, a f lexlble foam band, placed about t~e borehole centre core, allows the marker to be suspended at proper operatlng helght wlthln the borehole prlor to the installatlon of the anchorlng grout, The flexlble foam band alE;o prevents c3rout from enterlng the lnterlor of the marker anc~ thus creates the beneflclal equlvalent of a mount lng clevlce wlthln the borehole a~ter the grout has cured.
BRIEF D~ lON OF THF r)RAWING~
FIG . 1 18 a perspect lve vlew of a ~v~ l~ marker accordlng to the lnventlorl, ecluipped wlth retroreflectlve mat erlal .
FIG. 2 18 a perspectlve vlew of an annular spllt rlng mount lng devlce that may be used to mount the marker .
FIG. 3 18 a perE~pectlve vlew of a flexlble, closed-cell foam seal.
FIG. 4 18 a top plan vlew of the marker.
FIG . 5 18 a cross sect lonal vlew of the marker of Flgure 4 taken along sectlon llne 11-11.
FIG . 6 18 a croE~s sect lonal vlew of the annular rlng of FIG. 2 taken along sectlon llne 21-21.
FIG . 7 18 a cross sect lonal vlew of a marker system assembly lnstalled ln uclv 1,.
FIG. 8 18 a perE;pectlve vlew of a clo3ed cell foam band for use ln another embodlment of the lnventlon.
FIG. 9 18 a cross-sectlonal vlew of an: `~C"~ t oE

`-- 2~ 5~9~8 the lnvention using a cloaed cell foam bQnd as shown ln FIG.
8.
FIG. 10, comprl!31ng parts (a~, (b) and (c), 18 a serles of schemat lc drawillgs depict lng a snowplow blade pass across the marker.
FIG. 11 18 a cr~ss-sectlon of the flexlble retroreflectlve materlal ~lth 3M "VH8" adheslve lntegratlng the retrore1ector to the marker body.
FIG. 12 18 a perspectlve vlew showlng borehole drllllng e~ulpment and components and lllustratlng a novel lnstallatlon method for tlle p~v L marker system.
FIG. 13 18 a slde vlew, partly ln cross-sectlon, of the drllllng equlpment ant~ components of FIG. 12.
UE~L ~~ ON OF THE ~ ;~;u L.._.JuIr~
Referrlng lnltlally to FIGs. 4, 5 and 7, a body member oi~ a f lexlble ralsed pavement marker accordlng to the lnventlon 18 generally lndlcated at 10. The body member may be formed, e.g., by ln~ect:lon moldlng, of resillent materlal, preferably a flexlble pol5~urethane havlng a glass transltlon temperature (Tg) of -40F or lower. The body member 10 lncludes a tubular base portlon 31 and a generally dome-shaped top portlon 32. The top E)ortlon 32 18 dlmensloned and shaped to de~orm easlly when lmp~Lcted by vehlcular trafflc or a snowplow blade. The characterlzatlon of the top portlon as "generally dome-shaped" means the top portlon pro~ects upwardly from the base por~tlon but lt does not necessarlly have a slmple geometrlcal shape such as exhlblted by a hemlspherlcal dome, for example. The marker body top portlon 21~9~8 32 has a f lrst reglon 33 and a second region 1~ . The second reglon 14 ls more f lexlble than the f lrst reglon 33 .
Preferably, the greater flexlblllty of the 8econd reglon 14, as compared to the flrst reglon 33, 18 obtalned by maklng reglon 14 of thlnner materlal than reglon 33. The marker body top portlon also has a generally U-shaped thlckened sectlon 17, thlcker than the remalnder of the flrst reglon 33, whlch partlally enclrcles and ~deflnes an area to recelve a reflector descrlbed below, preferably a metalllzed cube-corner retroreflectlve sheetlng. The marker 18 unldlrectlonal, that 18 lt only reflects llght to vehlcles approachlng the marker from the dlrectlon of the reflector 12. The thlckened sectlon 17 helps protect the reflector from damage caused by a snowplow blade. The reflector 18 al~o protected by a recess encompassed wlthln the tl~lckened sect lon . The thlckened sectlon and recess allow a snowplow blade to strlke the thlckened sectlon 17 ratl~er than the reflector.
The lmpact of l he snowplow blade on thlckened sectlon 17 causes the tol? portlon 32 of the marker to deflect downwardly lnto the base port lon 31. Upon lmpact the f lrst reglon 33 can plvot dowm~ardly. The downward plvot 18 enabled, ln part, by hlnged reglon 18 and ln part lcular the hlnged reglon extendlng between llnes 35 and 36. When the flrst reglon 18 deflected, the second reglon 14 also 18 deflected downwardly, belng forced down ~y the flrst reglon 33, whlch 18 thlcker, and hence stlffer, than reglon 14, a~
shown ln Flg. 5. A generally concave sectlon 15 ln the thlnned reglon 14 of the top portlon 32 18 preferably provlded -- 215~!~08 to ald in deflecting the 'top portlon 32 of the marker body lnto the tubular base portlon 31. The area 15, and also the whole marker body, prefer~bly has substantlal mirror symmetry wlth respect to an lmagln~ry plane 11-11 blsectlng the flrst and second reglons of the dome. Area 15 18 acted upon by the contlnuance of thlck section 17 in the central top sectlon about pa rt la 1 ho 1 e 16 .
A fourth reglon a~soclated wlth deflectlon of top portion 32 lnvolves the Ul?per one third of base portlon 31.
Thls reglon i9b 18 characterlsed as flexlble having slmllar thlckness and flexlblllty cnaracterlstlcs as the second reglon 14 and belng typlcally one half the thlckness of the lower two thlrds of base portlon 31. Thls fourth flexlble reglon allows for lateral r vl t of tlle marker dome upon plow lmpQct.
Lateral movement of the dome decreases the lmmediacy of the flrst and second reglons of top portlon 32 to deflect into base portlon 31 thus lncreaslng the requlred response time of these regions resulting 1ll greater ablllty of the marker dome to survlve lmpact. The tlllnned upper reglon l9b of base portlon 31 18 an effectlve lateral hlnge for the marker dome.
The lower two tlllrds of base port lon 31 may also contaln a rellef area to l-eglster the marker body to a mountlng devlce wlth such mountlng devlce contalnlng a matlng lnverse relief. Thls reglstratlon of marker body and mountlng devlce ensures proper lnstallatlon of the mountlng devlce relatlve to trafflc dlrectlon and also prevents rotatlon of the marker body wlthln the mountlng devlce. Such reglstratlon rellef 23a 18 shown ln F15~s. 1 & 4, although the preferred r ~ 2 ~ ~ 8 ~ O 8 embodlment would situate such rellef opposlte to the impact section 33 of the marker body 10. A matlng lnverse rellef 23b iB shown ln Flg. 2 for the mounting devlce 20. Rotatlonal forces are exerted upon the marker body by the typically oblique impact angle of plowb]ades. When grout is used to install a marker body containing such registration rellef ln lts skirt section, the matlng registratlon rellef is formed in the grout.
With plow impact at thick section of reglon 17, lmmedlate and slmultaneous energy from the lmpact is imparted to thlnner, more f lexlble reglon 14 by reglon 17 through the thlck to thln transltlon reglon, about hole 16, deflectlng reglon 14 lnto the cavlty bounded by base portlon 31. A
hlnglng actlon occurs alang the ~uncture 34 of regions 33 and 14, as well as around the perlpheral hlnged reglon, speclflcally ln flexible thinned reglon 18, relatlve to the tubular base 31. Slmultaneous to these actions, the entlre marker top portlon 32 moves laterally, such - ,v~ t allowed by the flexlble reglon l9b of base portlon 31.
As seen ln FIG. 4, the first reglon 33 extends lnwardly f rom an arcuate base ad~acent a segment at the perlphery of the top portlon 32, to a terminating reglon 34 beyond the center of the top portlon. The arcuate ba3e of reglon 33 extends, as lndicated by lines 35, 36 of thls preferred embodlment, araund approxlmately 1/3 of the perlphery of the dome and provldes mount lng means and lmpact protection means for retroreflector 12. The second reglon 14 of body member 10 preferably 18 substantlally larger than the ~ 2~908 -first region 33. The hinged sectlon 18 preferably circumscribes the entlre upper inner perlphery of the tubular base portlon or skirt 31 and is thlnned, as shown in Fig. 5, to allow the top portion 32 to deflect lnto the base portlon 31 .
In preferred embodlments of the marker body accordlng to the lnventlom the thlckest sectlon 18 the thlckened sectlon 17 ln t~ne stlff flrst reglon 33 whlch 18 located around the area that recelves the retroreflector materlal 12. The sectlon 17 18 approxlmately 5 to 15 mllllmeters ~mm) thlck, preferably 8 to 12 mm. The area surrounded by thlckened s~ctlon 17 18 about 4 to 12 mm, preferably 6 to lO mm, thlck. The remalnder of the flrst reglon 33 18 approxlmately 3 to 9 mm, preferably 5 to 8 mm, thlck . The f lexlble secolld reglon 14 18 about 1 to 5 mm, preferably 2 to 4 mm, thll~k. The hlnged reglon 18 generally is about twenty percent less thick than the second reglon 14.
The lower flange l9a and l:he wall of base portlon 31 are approxlmately 3 to g mm, t~refera~ly 5 to 8 mm thlck. The thinned upper one third l'~b of base portlon 31 has the same thickness as second reglon 14 . This shows the f lrst reglon 33 to preferably have at least the same stlffness factor as the lower sldewall base portl~n 31, and the thln border reglon 18 hinges top section 32 vertlcally whlle the flexlble upper sidewall l9b of base portlon 31 hinges the top section 32 laterally from the lower sidewall of the base portlon 31. The flrst stlff sectlon 33 co~lld employ "corlng", dlscussed above, to produce stlffness wlthc~ut addlng bulk and subseguent 2lsssns lnert la to thls sect lon .
The preferred area of a vent hole 16 ls at least 25 mm but may be as large as 50 mm .
The preferred materlal for the marker body ls polyether polyurethane havlng, a Tg (glass transltlon temperature ) of about -40F or lower when measured under Dynamlc Mechanlcal Analysls, a shore hardness (measured under ASII~ standard D2240~
lggl ) of about 75A to 90A wlth 80A belng preferred, a tenslle strength e~ceedlng approxlmately 3,300 psl when measured under ASTM method D412-lg92, a low temperature st~ffness modulus rlgldlty of 1700 psl maxlmum at -40C when measured under ASTM D1053, a Vlcat Softenlng temperature of about 68C minlmum when measured under ASTM methocl D1525 (Rate B-l991).
A materlal that meets these requirements 18 "Estane"
5881 avallable f rom Goodri.ch Chemlcal Group.
Polyurethanes that possess such propert les provlde good deflectlon and endur~nce when struck by snowplow blades.
When colored black, such polyurethanes exhlblt extraordlnary durablllty under the cold and hazardous condltions ln whlch they are exposed.
The marker body member may be lntegrally colored when molded. An lntegrally colored p~v, - lt marker 18 one that has a colorant lncorporated into the marker body materl~l durlng manufacture as opposed to colorlng the surface afterwards. Whlte or yellow or other colors may ~e used as regulated for road-marklngs ln some ~urlscllctlons, but black ;

~ 21~8~8 1B preferred, for reasons explalned herelnafter.
Black coloration of the marker body, uslng, for example, l to 5 welght percent dlspersement of carbon black ln the body materlal ~nhAn~ the performance and longevlty of the marker as follows:
a) ~olar heatlng e~fects;
1) Solar heatlng of the marker melts snow on unplowed, snow-covered markers exposlng the p~ -' marker.
11) Solar heating asslsts ln evaporatlng molsture from the marker's lnterlor. Moisture otherwlse could bulld, freeze, and thereby lmpalr the marker's ablllty to survlve lmpact .
lli) Dlrect ~olar radlatlon 18 prevalent durlng "Cold Snaps" whlch are domlnated by hlgh barometrlc pressure.
Ralslng marker body temperature durlng dayllght hours reduces body embrlttlement, sometlmes referred to as "cold orderlng"
whlch may occur ln urethane wlth prolonged exposure to temperatures near the materlal's glass transltlon temperature (Tg). Solar heatlng makes the marker more pllable at all temperatures.
b~ Ralsed black-bodled markers perform a hlgh contrast functlon on snow-covered p~avement where the black body ltself contrasts wlth the whlte snow. Snow may be left on the pd\/~ lmpalrln~ retroreflectlve materlal performance.
Fresh snow 18 also reflectlve ln lts own rlght. Under these condltlons, the black bodles prove to be more vlslble by cont rast .
c) Ultravlolet solar radlatlon can penetrate and degrade materlals such as polyurethane . The black colorat lon may reduce penetratlon of UV radlatlon and extend the llfe of the marker.
Although the ma~ker body member 10, wnlch extends above the p~v t, normal ly 18 vlslble to motor vehlcle drlvers, it 18 preferred to provide lt with reflector materlal, especlally retroreflectlve materlal, whlch enhances vlslblllty of the marker, partlculary at nlght. A
retroreflectlve materlal hlas the ablllty to return a substantlal F~ortion of lncldent llght ln the directlon ~rom which the llght originate~.
P~lthough a number of known retroreflectors may be used, lt is preferred in the present lnventlon to use composlte retrore~lective sheeting that possesses a hlgh degree of flexlblllty, as well as good brlghtness and durablllty, and comprlslng cube corner retroreflectlve elements. A preferred cube corner retroreflectlve sheetlng 18 dlsclosed ln U.S. patent appllcatlon Serlal No. 08~139,914 flled October 20, l9g3 and lncorporated hereln by reference.
Brlefly stated, that patent appllcation describes a conformable prismatlc or cube-corner retroreflectlve sheetlng comprlslng a multltude of dlscrete cube corner segments that are conformably bonded together. Each cube corner segment comprlses a plastlc body F,ortlon having a substantlally planar front ma~or surface and slde walls and at least one mlnute cube corner retroreflectlve element pro~ectlng rearwardly from the l~ody portlon and deflnlng a cube corner polnt side of the 2:~a8!~8 cube corner segment. The word "conformable" 18 used hereln to descrlbe a materlal that 18 capable of belng shaped or formed.
In partlcular, the term "conformable" 18 used hereln to descrlbe materials such as carrler layers and sheetlngs whlch are omnl-dlrectlonally extenslble at some ambient appllcatlon temperature or elevated temperature and can take essentlally the same shape as non-planar substrates to whlch the materlals are conformed. The word "dlscrete" is used hereln to lndlcate that the cube corner segments are not rlgldly connected together. The phrase "conformably bonded together" and close varlants of thls phrase are used hereln to lndlcate that ad~acent cube corner segments are at least one of the following2 Il) separated by a gap of less than about 1 mllllmeter and bonded together through a conformable carrler layer; or (Z) separated by a gap whlch 18 substantlally fllled wlth a conformable resln that bonds the slde walls of ad:~acent cube corner segments together. E~ch cube corner retroreflectlve element typlcally has a plurallty of facets or faces and a base ad~acent the body portlon. Typlcally, substantlally all of the cube corner retroreflectlve elements located closest to the sld~e walls of the body portlons are lntact and capable of retr~oreflectlng llght.
The perlpherles of the cube corner segments can be deflned by a plurallty of separatlons e~tendlng from the cube corner polnt sldes to the front ma~or surfaces of the cube corner segments, the separatlons belng dlsposed between ad~acent cube corner segmel~ts.

-2~3908 .
The ad~acent c~ube corner segment3 can be conformably bonded together through a conformable carrler layer. The conformable carrier layer can comprlse a contlnuous, transparent fllm whlch is bonded to front ma~or surfaces of the cube corner element~ through an optlonal, typlcally transparent, adheslve l~.yer. For example, the conformable carrler layer can comprlse a 2 mll t50 mlcron) thlck, pla3tlclzed poly(vinyl chlorlde) fllm or polyurethane fllm (made from polyurethane pellets having the trade deslgnatlon 58277 f rom B . F . Goodrich Company, Specialty Polymers &
Chemical Dlvlslon of Cleveland, Ohlo or polyurethane pellets havlng the trade deslgnatlon PN-3429 or PN-03 from Morton Internatlonal, Speclalty Chemlcals Group, of Seabrook, New Elampshlre). Alternatlvely, the conformable carrler layer can comprlse lonomers of polyethylene copolymers such as SurlynTM
9910 from Du Pont Company, Polymer Products Department, of Wllmlngton, Delaware~ poly(ethylene-methacryllc acld) copolymers~ poly(ethylene-acryllc acld) copolymers~ or fluorocarbon polymers. The cube corner segments may comprlse, for exF~mple, poly(methyl methacrylate) resln. Both the conformable carrler layer and optlonal adheslve layer comprlse a low modulus materlal relatlve to the materlal of the cube corner reflectlve elements.
Other sultable ~lexlble cube-corner retroreflectlve aheetlngs are dlsclosed ln U.S. patent appllcatlon 08/472,444, whlch 18 a contlnuatlon-ln-part of U.S. patent appllcatlon 08/326,696, whlch ls a contlnuatlon-ln-part of U.S. patent .-- 2~8'~08 appllcatlon Serial No. OB~285,648, whlch 18 a contlnuatlon-ln-part of U. S.

- 24a -.-- 21~ g~8 appllcatlon Serlal No. 08,~139,433 flled 20 October 1993, all of whlch are lncorporated hereln by reference.
Brlefly, these patent appllcatlons dlsclose compos~te retroreflectlve sheetlngs that comprlse an array of substantlally ~ndl~r~"t~ t cube-corner elements and an overlay fllm or body portlon havlng flrst and second ma~or surfaces.
The cube corner element array is bonded to the overlay f llm' s flrst ma:lor surface. The array and the overlay comprlse first and second llght tran3mlsslble polymerlc materlals that have a dlfference ln elastlc modulus of at least 1 to 1.5 x 107 pQscals. The array of cub~e-corner elements preferably has an elastlc modulus greater than 16 x 108 pascals, more preferably greater than 18 x 108 pascals, and even more preferably greater than 25 x 1O8 pasc~ls. The overlay fllm preferably comprlses a low elastlc modulus polymerlc mater~al~ that is, one havlng an elast lc modu~.us less than 13 x 108 pascals, more preferably less than 7 x 108 pascals, and even more preferably less than 3 x 108 pascals. The cube-corner array preferably 18 f ractured around each cube-corner element to provlde a f ractured separat lon of each lndlvldual cube-corner element f rom surrounding cube-corner elements . The cube-corner sheetlng may possess a land layer between the overlay fllm and the cube-corner elements. The land layer preferably has a thlckness of less than about 10 percent of the average helght of the cube-corner elements. The backslde of the cube-corner elements 18 coated w~th a mlcrothln coatlng of metal such as chromlum, alumlnum, sllver, or comblnatlons thereof to promote ~1~89~8 retroreflectlvlty.
The conformable cube corner retroreflectlve sheetlngs descrlbed above perform very well on snowplowQble p~lV~ - ~t markers of this invent lon . It has been discovered that these retroreflective sheetings, partlcularly when the backslde of the cube corner elements are coated wlth metal, exhiblt excellent durabllity under the rigorous conditions required for snowplowable l~dV~ ~ markings. The retroreflectlve sheetings l~re able to provlde superior durability wlthout sacrlflclng retroreflective performance.
FIGs. 4 and 5 show a retroreflectlve sheetlng 12 preferably afflxed as mentioned above, to a recessed portlon of the marker body member 10 wlth a flexlble, weatherable adheslve system 13, speciflcally 3M VHB (Very High Bond) tape avallable from Mlnnesota Mlnlng and Manufacturlng Company, St.
Paul, Mlnnesota. Retroreflector colors may be speclflc and regulated relatlve to thelr position and functlon when used on a roadway.
FI~. ll shows the constructlon of highly flexlble retroreflector 12 and the hlghly flexlble adhesive system 13 applled to the marker body 10. The drawing is proportionate in thlckness with the retroreflector materlal belng approxlmately 0.010 lnches thlck and the adheslve system approxlmately 0 . 020 lnches thlck . Due to the hlghly f lexlble adheslve 58,60 (a hlgh shear acrylic type), the adhesive 58 integrates about the entlre metalllsed cube corner facet section 57 of the assembly such that the thickness dimensions ~ 2~g~8 of the two components, retroreflector 12 and adheslve component 13, overlap.
The effectlve }ligh surface area created by the mlcroprlsmatlc cube cornel elements allows an exceptlonally strong bond to be achleved between the cube corner sheetlng and the adheslve.
The fact that tlle cube corner elements 57 are In~ r~nrlf~nt of each other, belng hlnged at thelr bases where they are bonded to flexlb:Le lamlnate layer 56, allows the total comblnatlon of retroreflector 12, adheslve lamlnate 13 and the marker body lO to act ln concert and remaln bonded when flexed by lmpact of marker body lO. The lnterlayer 59, of the adheslve system, 1~3 a flexlble, reslllent, acryllc foam. The retroreflector top lamlnate 55 18 a flexlble, abras lon res lstant f 1 lm .
In thls lnvention, there is little or no perlpheral growth of the marker body about the upper reglon l9 of base portlon 31 when sub~ected to plow lmpact, allowlng the marker to be lnstalled ln pavemellt wlth a rlgld grout or alternatlvely wlthln an al~nular rlng mountlng devlce that has been placed ln a cavity 11l the pavement . A f lexlble grout may be deslrable in certain al?pllcat ions and may be used . The marker body 18 preferably vented to atmosphere to prevent entrapped alr wlthln the cavlty from counteractlng deformatlon of the top portlon of the body member. As lndlcated above, the vent also asslsts ln releaslng molsture from the p~v, -rt marker's lnterlor. Ventl]~g may be achleved by, for example, completlng a partial hole 16 in the top-sectlon of the marker body 10 or by vent channels in an annular ring mountlng device (discussed below) if used to mount the marker body in the pavement. The combinationl of marker ventlng and ultlmate f lexlblllty of the pavemenlt marker, results ln a marker body member that presents llttle reslstance to deformatlon by snowplow blades . Low re~ lstance to lmpact f rom snowplow blades prevents cuttlng an,d catchlng actlons on the marker body members .
FI~s. 2 and 6 show a mountlng devlce ln the form of an annular rlng 20 that ma.y be used as an alternat lve to mount lng the marker ln pavement wlth a rlgld or f lexible grout. The mounting device comprlses an annular wall of flexlble synthetlc materlal havlng an lnner surface 25 and an outer surface ~not referen,ced). The lnner surface 25 18 adapted to mechanically en.gage an ob~ect, in partlcular a marker body member (although the mountlng devlce could be used to mount other useful ob~ects ln a pdV~ ~nt borehole). The outer surface of the mountlng devlce 20 has a plurality of annular ribs 26 adapted to engage the p~v, -- 1 around a borehole. The rlbs preferably have a dlameter larger than the dlameter of the borehole Ipreferably at least 3.3 percent larger) 80 that the rl~s deflect upwardly when engaged with the p~v~ . The ribs' upward deflectlon allows the marker to reslst removal f rom the borehole as shown ln Fig. 7 .
The mountlng devlce can perform multiple functlons:
mountlng the marker wlthin the pdV~ -~t cavlty at a proper _ _ - 2 ~ 9 0 8 height; provldlng ea3y, fEIst replacement of marker body members when refurblshlng 18 recaulred; and counteractlng the asphalt creep process, whi ch could compromlse marker cavlty lntegrlty and lead to unsafe roadway condltlons. Under hot weather condltlons and heEIvy vehlcular trafflc, asphalt becomes pllable and has a tendency to "creep" and flll cavltles in p~v, ~. If the creep 18 left unchecked, the lntegrlty of the marker's base portlon may be compromlsed and depresslons may form ln t~le ~v, l a~out the perlphery of the marker. In wet, cold weather, lce could form ln these depresslons presentlng a ~lar~ard to trafflc.
As shown ln FlgE;. l and 2, the lnner surface 25 of rlng 20 18 deslgned to recelve flange lga of the base portlon 31. The outer surface of base portlon 31 preferably flts snugly agalnst the lnner surface 25 of rlng 20 . The snug f lt can reduce lngress of molEIture and debrls lnto the assembly that could compromlse the p~v~ - ' marker's performance. The snug flt could be llmlted to the lower reglons of the marker body's base portlon 31 anc~ mountlng devlce rlng 20, as shown on the left slde of FIG. ,~ to provlde an annular alrspace or gap 28 between the base portlon 31 of the marker body member and the lnner surface 25 of the mountlng devlce rLng ln the upper reglon of the base E~ortlon 31. Thls gap 28 provldes addltlonal flexlblllty to the marker top-sectlon allowlng a faster, more compllant reEiponse of the top portlon 32 of the marker to plow lmpact to l:urther lmprove the marker' 8 ablllty to survlve. As mentloned, the upper one thlrd of the marker , 2~al890g body base portlon 31 may be thlnned to one half the wall thickness of the lower portion to provlde addltlonal lateral flexlbllity to the marker body 10. This geometry acts ln concert wlth the gap 28 in the mountlng devlce 20. Alr currents on roadway surf~ces caused by hlgh speed trafflc flow can tend to keep such a gap clear of partlculates. In the case of no annular rlng mount lng devlce ln use as shown ln Flg. 9, where the marker body 18 grouted ln place, partlal groutlng 61 above the flange l9a can produce such a gap.
The mount ing devlce rlng may be pressed lnto a bored p~v L cavlty wlthout grout. Thls allows for rapld lnstallatlon because cavities, bored ln the ~v~ t wlth water-flushed drllls, res~ulre drylng before groutlng. An efflclent method of lnstalllng the marker 10 or another ob~ect and the mountlng devlce rlng 20 lnvolves presslng the preassembled comblnat lon of the mount lng devlce 20 and the ma~ker 10 lnto the ~v~ 1 borehole 40. Thls may be accompllshed manually, u~llng a hammer, or a hydraulic power ram. The drlll that formed the borehole, may be used for thls purpose Q8 lt contains such a hydraullc power ram.
FIGS. 12 and 13 show borehole drllllng equlpment 70, lncludlng unlque drlll blt 74 and lnsertlon flxture 77 and lllustrates a novel lnstallatlon method for the pavement marker system. The hydraullcally powered drllling equlpment 70 18 typlcally mounted ~n a vehlcle 71 whlch also carries a hydraulic power unlt whlch 18 rated, typlcally between twenty and elghty horsepower. The vehlcle 71 (shown only ln portlon) 2~ 58908 may also carry hundreds of gallons of water for cooling the drlll blt 74 and f lushing debrls f rom the pavement borehole 40. A hydraullc motor 73 rotates the drlll blt 74 during borehole drllllng whlle hydraullc ram 72 slmultaneously drlves the drlll blt 74 downwart l lnto the peiv~ ~ 42. Water 18 pumped lnto the lnterlor of the drlll blt durlng the drllllng operatlon. Drlll blt 74 contalns unlt~ue "kerf" cuttlng components 75 ( located orl the upper perlphery of the drlll blt ) to ensure ~d~ , Dlarker8 10 are lnstalled at proper operatlng depth ln the pavement 42. The "kerf cutters" cut a kerf 43 whlch clrcumscri~)es the borehole at the pdV.- 1. top surface when the lower cuttlng components 76 of the drlll blt 74 have reached proper borehole depth. The drlll blt 74 18 then ralsed by hydraullc ram 72 and the borehole 40 18 cleared of water and debrls. A E)reassembly of marker 10 and mountlng devlce 20 18 then placed ln the borehole 40 wlth the lower heel of the mountlng device 20 belng small enough to flt ln the borehole 40 thus pro~idlng a centerlng functlon for the preassembly. An lnsertion f lxture 77, havlng a lower f lange 78, whlch conforms to and centers on the mountlng devlce upper rlm 24, 18 placed over tlle preassembled marker/mounting devlce. The lnsertlon devlce does not touch the marker 10.
The lower flange 78 of t~le lnsertlon flxture 77 extends radlally beyond the perl~?hery of the mount ing devlce 20 but 18 small enough ln radlal d:~menslon to flt wlthln the dlameter of the kerf 43 of the borehole 40 . The f lxture 77 also has an upper surface 79 made frt~m hlghly reslllent materlal deslgned 21~8908 to be cont~tcted by the dr:Lll blt lower cuttlng elements 76 wlthout damaglng the flxttlre 77 or the cuttlng elements 76.
The drlll blt 74, whlch remalns centered above the borehole 40, is then drlven downwal-ds by hydraullc ram 72 thus contactlng and drlvlng the insertlon flxture 77 and the marker/mount lng devlce asf~embly lnto the borehole 40 . The downward travel of all components 18 controlled and stopped when the lower radlally e:~tended flange 78 of the lnsertlon f lxture 77 contacts the kerf face 43 of the borehole 40 . In thls method, no excesslve hydraullc presf3ure 18 applled to the devlces mounted wlthln the borehole as proper lnsertlon depth of the markerJmountlng devlce is controlled by the relatlve dlmenslon of drlll blt cul~tlng elements 75,76 and the lnteractlon of lnsertlon :Elxture flange 78 and borehole kerf 43. Durlng the lnsertlon method, the rlbs 26 of the mountlng devlce 20 deform upwards and grlp the lnner surface of the borehole 40. The drlll blt 74 18 not rotated by the hydraullc motor 73 durlng the lnsertlon method nor 18 water pumped to the drlll blt 74 . Proper insert lon of the p~v~ - ~ marker 10 and mountlng devlce 20 by thls method 18 efflclently accompllshed ln a few seconds. Rlng seal 30 may or may not be used ln thls method.
Flgure 7 shows a sectlonal vlew of the marker lO, mounted ln an annular rln~g mountlng devlce in a pavement cavlty 40. The grlpplng rlbs 26 are shown deformed and captured wlthln a grout 50 ln~ected between the outer surfaces of the mount lng device rlng 20 and the pavement 42 . The upper rim 24 resides ~ust be3~ow the pavement surface 41 wlthln the vertlcal cut dlmenslon. 'rhe lnner top-sectlon 27 of rlng 20 i8 at a reduced elevatlon to the uppermost rlb to avold capture by a snowplow blade and resldes below the pavement surf ace 41.
Flgure 2 8hows ~I plurallty of axlally extendlng channels 22, each spaced ~It approxlmately nlnety degrees to an ad~acent channel. The ch~lnnels are dlsposed on the outer surface of the annula~ rlllg 20, to vent the lnterlor cavlty and may alternatlvely be ~sed as channels for grout 50 to further anchor the rlng lllto the pdV~ t. It 18 contemplated that a slngle channel may provlde satlsfactory ventlng, but a plurality of channels 18 I?referred to ensure good ventlng and to avold the posslblllty of lnadequate ventlng whlch could occur if a slngle channel were to be blocked, for example, by debrls. Use of grout depends on slze and quallty of the bore cavlt les, pavlng materlal~ and }J~:IVG 1. condlt lons . The rlng 20 of the mountlng devlce may be fabrlcated as a slngle component (l.e. lntegral) or lt may be molded as a plurallty of separate parts adapted to be locked together as shown ln Flg. 2 wlth the rlng fabrlcated ln two pleces Sectlonlng the rlng provldes a beneflt r~gardlng potentlal pro~ectlve threat lf a marker and rlng becol;ne dlslodged on the roadway ln that the rlng half welghts ln the order of 60 grams and the f lexlble urethane marker ln the order of 160 grams . Such welghts and materials 2re unllkely to present a slgnlflcant threat to motorlsts. A preferred materlal for the rlng 18 a 9 O g hlgh denslty polyethylene such as HD 10062~ avallable from the Dow Chemlcal Company . The mount lng devlce ring 20 pref erably conforms to the y~v~ 1 topography and by havlng a f lexlble body member and, preferably, also conforms to the lnstalled alt itude . A ma~or advantage of thls system 18 that p~v, - ' markers can be prled ln and out of the rlng wlth ease.
Installatlon and removal of pavement markers may be accompllshed wlth a slmple tool. The markers remaln ln the rlngs under the abuslve forces of vehlcular trafflc and plows as these forces act normal to the pry removal force.
FIG. 3 shows a rlng seal 30 that 18 dlmensloned to f lt the p~v~ 1 cavlty lmmedlately below the annular rlng 20 .
It may be manufactured from closed cell foam materlal such as cross-llnked polyethylene foam (for example, T200 avallable from Voltek Inc ., Lawrence, Mass . ) and 18 lntended to compress when the mountlng devlce rlng 20 18 installed above lt as shown ln Flgure 7. The rlng seal 30 preferably 18 reslllent 80 that a f luld seal can be malntalned between the pd\~
marker's lnterlor and the amblent envlronment. The fluld seal prevents molsture from enterlng the p~v~ L marker's lnterlor. The rlng seal 30 occuples space ln the y~v, cavlty below the rlng 20 preventlng molsture from collectlng ln the pavement cavlty. ~lolsture, when frozen, can expand to drlve rlng 20 upwards exposlng lt to the plowblade. Even lf rlng seal 30 does not fully occupy a gap below mountlng devlce rlng 20, due to excesslve pt~VI t bore cavlty depth, lt stlll effectlvely protects the mountlng devlce rlng 20 from belng . 21~g908 forced upwards ln the bore cavlty by freezlng molsture The expansion of molsture when freezlng ln the bore cavlty would tend to compress the rlng seal 30 before lt would act upon the hlgh frlctlon mounted mountlng devlce rlng 20.
Dlffering comblnatlons of the system components may be used for system lnstallatlon under varlous condltlons.
Concrete presents a relat lvely smooth bored cavlty that may reduce the frlctlon lock of the polyethylene rlng. As shown ln FIG. 7, grout 50 may then be used to lock the rlng 20 ln the pavement cavlty 40. Concrete generally has a low poroslty, and therefore mclsture wlthln the cavlty may be slow to draln. Rlng seal 30 can be used under such clrcumstances to keep molsture f rom resldlng below the rlng. The seal 30 would render vent channels 22 (FIG. 2) lnoperatlve for ventlng and 80 too would grout 50. In thls sltuatlon marker ventlng 16 can be accompllshed by provldlng a hole 16 ln the upper portlon of the marker body 10. ~For ease of moldlng the body member of the marker, only a partial hole 18 formed. It can easlly be completed by pur,chlng or drllllng. ) Grout 50 also may be used ln asphalt ~d~`e- l. when the cavlty 18 overslzed due to drlll equlpment eccentrlclty. The grout adheres to the pavement materlal and can form a mechanlcal lock ln the plurallty of rlbs 26 of t~le annular rlng 20. In appllcatlons where vehlcular trafflc 18 low ln volume, for example a parklng area, marker bodles 10 could be lnstalled ln bored cavltles dlrectly wlth rlgld grout 50, or wlth softer more f lexlble grouts . The gro~lts may ~e used wlthout annular rlng - 35 ~

- 2i~8908 20 because these lnstallat ions are unllkely to promote marker deterloratlon, and ease of replacement 18 less a concern.
Rlng seals 30 are not necessary for appllcatlons that do not lnvolve annular rlng mountlng devlces 20 because the grouts are used to set marker helght and perform the functlon of the seal 30 and also perform the marker capture function, otherwlse performed by th~ annular rlng mountlng devlce.
Agaln, vent lng may be accompllshed by provldlng a hole 16 ln the marker body 10.
Referrlng to FlaJures 8 and 9, another embodlment of the inventlon 18 shown wh~ch uses closed cell, ~ioam band 51.
Thls band may be employed when the marker body member 10 18 lntended to be anchored ln the p~v, -- t wlth grout 52. The band 51 is stretched and lnserted about the central ralsed core sectlon ln the borehale 40. The body member 10 18 then posltloned onto and about the foam band 51, wlth the band 51 reslllently compresslng and supportlng the body member 10.
The body member 10 may be manually ad~usted to proper lnstallatlon helght relatlve to the pavement surface 41 by the Z0 use of the foam band ln thls embodlment. Grout 52 18 then lnserted lnto the borehole about the perlphery of the marker body member 10. The foam band 51 prevents grout from enterlng the lnterlor oi~ the borehole cavlty 40 and, more lmportantly, prevents grout from enterlng or resldlng behlnd the "heel" 53 of the marker lower base p~ortlon opposlte the flange. The grout 52 remalns ln the pc,v, ~ cavlty and may not need to ~e replaced ln the refur~lshlng operatlon. In essence, thls . 21S;~908 method of lnstallation of the marker body creates the benef lclal equlvalent of a mount lng devlce wlthln the borehole after the grout has cured. Partlal groutlng 61 as shown ln Fig. 9 may also be employed to create the benef lcial equlvalent of the mountlng device gap 28 shown ln Flg. 7. As both grout 52 and foam band 51 effectlvely seal the lnterlor of the body member 10 f rom the amblent environment, the hole 16 is provlded to vent the marker body member 10 to atmosphere as shown ln Flgure 9. Like the foam seal 30 shown ln Flgure

3, the foam band 51 shown ln Flgure 8 may be fabrlcated from closed cell polyethylene foam.
The act lon of the marker body ln response to lmpact by a snowplow blade 18 schematlcally lllustrated ln Flg. lO, parts (a), ~b1 and (c~. Fig. 10 uses the same reference numbers as Flg. 5 wlth the addltlon of reference number 54, whlch denotes a snowplow blade, and reference letter "A" whlch shows the low tangent angle of lmpact A malntalned across the flrst stlff reglon 33 of the marker body from lnltlal lmpact, Flg. 10, part (a), to later stages shown ln Flg. 10, parts (b) and (c). Flg. 10 also shows the flexlble second sectlon 14 deformlng lnto the lower portlon of marker lO as the plow strlke progresses, alded by the relatlvely flxed but hlghly f lexlble hlnged area 18 around the perlphery of the top port lon of the marker 10 and also alded by the f lexlble upper base region l9b whlch provldes lateral r,~ v~ 1 of the top port lon of the marker body .
Another hlnge polnt 18 shown as hlnged area 34 --- 21~8908 locate~ between the flrsl stlff reglon 33 and the flexlble second reglon 14.
An advantage of the present lnventlon 18 that lt ls essentlally a totally no~l-metalllc system. When pav ' 18 resurfaced cast metal u~llts are extrlcAted from p2~V ' wlth tools such as ~ack-hammers. The system of thls lnventlon may be consumed by a "scarlf :Ler" machlne employed ln resurfaclng maklng removal of the mal~kers unnecessary. All ~ ..1.8 would melt and/or lntegrate lnto the used asphalt that may be recycled for subseguent use.
Whlle the lnvelltlon has been described wlth reference to preferred embodiments lt wlll be understood by those skllled ln the art that varlous changes may be made and equlvalents may be subst~tuted for eleme~ts thereof wlthout dep~rtlng from the scope of the lnventlon deflned by the followlng clalms.

Claims (68)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A raised pavement marker for installation in a pavement borehole, the marker comprising a body member having a base portion and a generally dome-shaped top portion, the top portion having a first stiffened region and a second flexible region, the first stiffened region having a surface for receiving a retroreflective material, the second flexible region assisting in allowing the top portion to be deflected downwardly into the base portion when the top portion receives a force on the first region, the pavement marker being sufficiently resilient to enable the top portion to return to its generally dome-shaped configuration upon release of the force.

2. A marker as claimed in claim 1 wherein said top portion is joined to said base region by a surrounding border region more flexible than said first and second regions.

3. A marker as claimed in claim 2 wherein said base portion is tubular including a lower section having a first thickness and an upper section having a second thickness less than said first thickness.

4. A marker as claimed in claim 3 wherein said second thickness is approximately one-half said first thickness.

5. A marker as claimed in claim 4 wherein said first section has a height approximately twice the height of the second section.

6. A marker as claimed in claim 5 wherein said second region is substantially larger than said first region.

7. A marker as claimed in claim 6 wherein said first region extends from said border region inwardly to beyond the center of the top portion.

8. A marker as claimed in claim 7 wherein said first region comprises approximately 1/3 of the top portion.

9. A marker as claimed in claim 7 wherein said second region has a downwardly concave portion disposed near said first region.

10. A marker as claimed in claim 7 wherein said concave portion is substantially symmetrical with respect to an imaginary plane bisecting said first and second regions.

11. A marker as claimed in claim 10 wherein said first region has a recessed portion adapted to receive a retroreflective element, said recessed portion being surrounded by a thickened section.

12. A marker as claimed in claim 11 wherein said retroreflective element is secured to said recessed portion by a flexible weatherable adhesive.

13. A marker as claimed in claim 12 wherein said body member is formed of polyurethane having a glass transition temperature (Tg) of -40°F or lower.

14. A marker as claimed in claim 13 which is colored black.

15. A marker as claimed in any one of claims 11 to 14 wherein said first region has a first average thickness, said second region has a second average thickness and said border region has a third average thickness, and wherein said second average thickness is less than said first average thickness and said third average thickness is less than said second average thickness.

16. A marker as claimed in claim 15 wherein said first average thickness, not including said recessed portion and said thickened section, is approximately 3 to 9 mm, preferably 5 to 8 mm, said second average thickness is approximately 1 to 5 mm, preferably 2 to 4 mm, said third average thickness is approximately 20% less than said second average thickness.

17. A marker as claimed in claim 16 wherein said recessed portion has an average thickness of approximately 4 to 12 mm, preferably 6 to 10 mm, and said thickened section has a thickness of approximately 5 to 11 mm, preferably 8 to 12 mm.

18. A marker as claimed in any one of claims 1 to 14 and 17 including means for venting said marker to atmosphere.

19. A marker as claimed in claim 18 wherein said means for venting comprises a hole in said top portion.

20. A marker as claimed in claim 18 wherein said means for venting includes a plurality of axially-disposed channels spaced around said base portion.

21. A marker as claimed in claim 19 wherein said base portion has an end opposite said top portion, said end having an outwardly extending circumferential flange.

22. A marker as claimed in any one of claims 1 to 12 inclusive wherein said body member is formed of polyurethane having a glass transition temperature (Tg) of -40°F or lower.

23. A marker as claimed in claim 22 which is colored black

24. A marker as claimed in claim 22 including means for venting said marker to atmosphere.

25. A marker as claimed in claim 24 wherein said means for venting comprises a hole in said top portion.

26. A marker as claimed in claim 22 wherein said means for venting includes a plurality of axially disposed channels spaced around said base portion.

27. A device for mounting an object in a pavement borehole, said device comprising an annular wall having an inner surface and an outer surface, said inner surface being adapted to frictionally engage said object and said outer surface having a plurality of annular ribs adapted to engage said pavement within said borehole.

28. A device as claimed in claim 27 wherein said ribs have a diameter slightly larger than the diameter of said borehole whereby, when said device is forcibly inserted in said borehole said ribs deflect upwardly in engagement with the peripheral sidewall of the borehole to resist removal from the borehole.

29. A device as claimed in claim 28 wherein it comprises two matching pieces which fit together to form said annular wall.

30. A device as claimed in claim 29 wherein said inner surface has an annular recess to receive an annular flange on said object.

31. A device as claimed in claim 30 and further comprising an inwardly directed bottom flange for receiving a bottom surface of said object.

32. A device as claimed in claim 31 wherein at least one axially extending channel divides the ribs.

33. A device as claimed in claim 31 including a plurality of axially disposed channels spaced apart around the device and dividing the ribs.

34. A marker as claimed in claim 1 wherein said base portion is cylindrical and engages an inner surface of an annular wall of a device for mounting it in said borehole, said device being formed of flexible synthetic material, said wall having an outer surface provided with a plurality of ribs adapted to engage said pavement within said borehole.

35. A marker as claimed in claim 34 wherein said ribs have a diameter slightly larger than the diameter of the borehole whereby, when said device is forcibly inserted in the borehole, said ribs deflect upwardly in engagement with the pavement around said borehole to resist removal from the borehole.

36. A marker as claimed in claim 35 wherein said second region of said body member is substantially larger than said first region.

37. A marker as claimed in claim 36 wherein said first region extends from said border region inwardly to beyond the center of the top portion.

38. A marker as claimed in claim 37 wherein said first region comprises approximately 1/3 of the top portion.

39. A marker as claimed in claim 37 wherein said second region has a downwardly concave portion disposed near said first region.

40. A marker as claimed in claim 38 wherein said concave portion is substantially symmetrical with respect to an imaginary plane bisecting said first and second regions.

41. A marker as claimed in claim 39 wherein said first region has a recessed portion adapted to receive a retroreflective element.

42. A marker as claimed in claim 39 wherein said retroreflective element is secured to said recessed portion by a flexible, weatherable adhesive.

43. A marker as claimed in claim 41 wherein said resilient material is polyurethane having a glass transition temperature (Tg) of -40°F or lower.

44. A marker as claimed in any one of claims 34 to 43 wherein said top portion is joined to said base region by a surrounding border region more flexible than said first and second regions, and wherein said base portion is tubular including a lower section having a first thickness and an upper section having a second thickness less than said first thickness.

45. A marker as claimed in claim 44 wherein said second thickness is approximately one-half said first thickness.

46. A marker as claimed in claim 45 wherein said first section has a height approximately twice the height of the second section.

47. A marker as claimed in claim 46 including means for venting said marker to atmosphere.

48. A marker as claimed in claim 47 wherein said means for venting comprises a hole in said top portion.

49. A marker as claimed in claim 47 wherein said means for venting comprises a plurality of axially extending channels dividing said ribs.

50. A marker as claimed in claim 49 wherein said tubular base portion has an end opposite said top portion, said end having an outwardly extending circumferential flange.

51. A marker as claimed in claim 50 and further comprising a ring of closed cell foam material disposed beneath said inwardly directed bottom flange.

52. A marker as claimed in claim 51 wherein said foam material is flexible grade polyethylene.

53. A marker as claimed in any one of claims 45 to 52 wherein said resilient material is polyurethane.

54. A marker as claimed in claim 53 wherein said flexible synthetic material is high density polyethylene.

55. A raised pavement marker that comprises a body member having a base portion and a generally dome-shaped top portion, said top portion having a hole venting said marker to atmosphere and being capable of being deflected downward into the base portion upon receiving a force on the top portion, the pavement marker being sufficiently resilient to enable the top portion to return to its generally dome-shaped configuration upon release of the force.

56. A raised pavement marker as claimed in claim 55 wherein said top portion has a first region and a second region, said second region being more flexible than said first region.

57. A marker as claimed in claim 55 wherein said top portion is joined to said base portion by a surrounding border that acts as a hinge, allowing the top portion to be deflected downwardly into the base portion.

58. A marker as claimed in claim 57 wherein said base portion is tubular including a lower section having a first thickness and an upper section having a second thickness less than said first thickness.

59. A marker as claimed in claim 58 wherein said second thickness is approximately one-half said first thickness.

60. A marker as claimed in claim 59 wherein said first section has a height approximately twice the height of the second section.

61. A method of mounting a pavement marker comprising the steps of forming a borehole in pavement with a central core raised above the bottom of the borehole but below the surface of the pavement, said core having a predetermined diameter, stretching a band of closed cell foam material, which has an unstretched diameter less than said predetermined diameter of the central core, and inserting it about said core, positioning a tubular base portion of a marker onto and about said band with the band compressing and supporting said marker so that said marker has a top portion extending above the surface of the pavement.

62. A marker as claimed in claim 1 in combination with a band of closed cell foam material, said band being adapted to be stretched and inserted about a central core of a borehole in pavement, said core being raised above the bottom of the borehole but below the surface of the pavement, said band having an unstretched diameter less than the diameter of said central core, said base portion of said marker being adapted to be positioned onto and about said band with the band compressing and supporting said marker so that said top portion of the marker extends above the surface of the pavement said marker being anchored in the pavement with grout.

63. The combination comprising a device for mounting an object in a pavement borehole and a ring seal of flexible, closed-cell foam material, said ring seal being adapted to be disposed at the bottom of the borehole with said mounting device above it, said ring seal being compressed when the mounting device is installed above it in the borehole.

64. A pavement marker adapted to protrude from a roadway surface when installed thereon, the pavement marker comprising a body member having a base portion and a generally dome-shaped top portion, the top portion having an area for receiving a retroreflective sheeting, the top portion being deformable so that when a force is received thereon the top portion can be deflected downwardly into the base portion, wherein at least the top portion of the pavement marker is comprised of polyurethane that is integrally colored black.

65. A method of installing in pavement an assembly comprising a device and a mounting device ring having an upper end and a lower end, said method comprising the steps of, (a) drilling a hole in the pavement with a drilling machine having a power ram and an end provided with a drill bit, (b) withdrawing the drill bit from the hole while maintaining it centered with respect to the hole, (c) placing an insertion fixture over the end of said drill, said fixture having a lower annular surface conforming to the mounting device ring, a cavity to receive the device without interference, and a highly resilient upper surface to protect the device from damage by the drill bit of said drilling device, (d) placing the lower end of the mounting device of said assembly in said hole, (e) lowering the insertion fixture onto said ring, and (f) operating the power ram, without rotating said drill bit, to drive the fixture and the assembly downward until said assembly is inserted a desired distance into said hole.

66. A method as claimed in claim 65 wherein said device is a pavement marker.

67. A method of installing a pavement marker in a pavement borehole, which method comprises:
(a) providing the pavement borehole;
(b) placing the pavement marker having a top portion and a base portion in a mounting device such that the top portion protrudes from the mounting device, the mounting device comprising an annular wall having an inner surface snugly engaging the base portion of the pavement marker and the outer surface being adapted to engage the pavement borehole; and (c) placing the mounting device in the pavement borehole.

68. A method as claimed in claim 65 which includes forming an annular kerf extending outwardly adjacent the top of said hole and driving the fixture and the assembly downward until an annular flange on said fixture is seated in said kerf, whereby said assembly is inserted said desired distance into said hole.