CA2030906A1 - Rumble strip for highways - Google Patents

Abstract

Abstract of the Disclosure RUMBLE STRIPS FOR HIGHWAYS

The rumble strips comprise wide (5-10 cm) strips of rubber let into grooves in the road surface. The groove is out by a reflex-percussion machine (in which the cutting bit is forcibly withdrawn from the surface the instant the bit strikes the surface, so that the material flakes by induced tension). The rubber strip is wide and bulky, and provides good rumble intensity without interfering with tire passage.
The rubber strip may be held in place with a shaped anchor strip, made of metal and bolted to the base of the groove.
The strip may extend across the full width of a traffic lane, or may be short.

Description

-- 2~30~06 RUMBLE STRIP FOR HIGHWAYS

This invention relates to the provision of rumble strips and the like in highways.

Ru~ble strips are strips which are placed across one or more lanes of a highway at the approach to a road junction or other hazard. The rumble strips are provided where it is dee~ed desirable to present drivers with an audible warningJ
that they may be especially alerted to the hazard. As the vehicle runs over the runble strips, the driver hears a rumbling noise. The driver also "feels" a physical change in the road surface/ which also serves to alert him.

Practice varies somewhat, but typically the rumble strips are arranged in four groups of oight or ten strips positioned 80, 60, 40, and 20 metres from the hazard.

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BACKGROUND TO THE INVENTION

One of the major problems ~ith rumble strips, as with other road hazard markings, is that anything that protrudes, even slightly, above the surface of the roadway imposes a very `~
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tight restriction on the use of snow plows.
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The impact of a snow plo~ blade against a rumble strip cannot be allowed to be too vigorous, or the rumble strip . . , .: ~ - - , ~ : : .: :: : . . .
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-- 2will be da~ged -- and, perhaps even wor~e, the edge of the snow plow blade also may be da~aged. If the snow plow is ~oving at any significant speed ~hen the i~paot occurs, and if the da~age takes the for~ of pieces being broken fro~ the ru~ble strip, or fro~ the blade, the broken pieces ~ay be hurled at other road users.

On the other hand, if the ru~ble strips are so smooth and gentle that a sno~ plow blade passes easily over the strips, then the proble~ arises that the passage of the tires of vehicles ~ay not produce enough ru~ble intensity to perfor~
the pri~ary function of alerting the driver.

A conventional ru~ble strip co~prises a narrow ~ound of asphalt. This ~ound is perhaps 1 cm high above the road surface at its ~idpoint, and is typically 15 cm wide, being feathered into the surface at the leading and trailing (front and rear) edgss. The ru~ble strip is applied to the road surface after the surface itself has been flattened.
' ' Such si~ple ru~ble strips are caused to adhere to the road surface basically by ~eans of an adhesive. The adhesive is not as strong as the asphalt, and asphalt itselfJ while of course hàving very good bulk strength, is not at all strong when in the for~ of feathered edges. Also, the ru~ble strip inevitably is subject to accentuated wear, si~ply because the strip does protrude above the road surface. For these ~, reasons, runble strips in the for~ of asphalt ~ounds tend to , .: .. - . . . .

break uP, and they are not well regarded by highway engineers.

In place of asphalt, mounds of conorete have been used, especially on concrete roads, but concrete is little better than asphalt in this regard.

It has been proposed to cut a groove~ with a saw, in the road surface, and to secure a strip of rubber in the groove.
The problem here lies in the fact that, although the saw-cut groove may be perhaps 2 cm deep, the width o~ the groove, as produced by the saw blade, is very li~ited, the maxi~um groove width bein~ of the order of 5 mm or so. The result of this limitation is that only very small, ~ sy, pieces of rubber can be used. If the groove is widened by the process of repeatedly passing the sa~ along the ~roove, it becomes very difficult to hold the width of the groove accurately constant along its length, with the result, if that method were used, that sometimes the rubber would work loose.

GENERAL FEATURES OE THE INVENTION

In the invention, the ru~ble strip co~prises a strip of rubber, but unlike the flimsy rubber strips associated with ;~-narrow saw-cut grooves, the rubber strip in the invention is several centimetres, as ~uch as 5 or 10 cm, wide, and is . .

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correspondingly deep. In the invention, the groove in the road surface, Eor receiving the rubber ru~ble strip, is not cut by ~eans of a saw but is cut by the ref]ex-percussion process, and preferably by the ~odification of the reflex-percussive process in which the cutting tool does not rotate.

British patent publication nu~b0r GB-2215257 (CLARKE, Sept ?
1989) shows how the reflex-percussion process may be carried out with non-rotating cutting bits.

Such a process, it has been found, is very effective in cutting deep Nide grooves in concrete and asphalt. The resulting grooves are tre~endously accurate as regards constancy of width. Also the cut is very clean, and the lips or edges of the groo~-e are quite sharp. The base of the groove, as cut~ is easy to control accurately as to its depth, and the surface finish which it is possible to achieve on the base of the groove would be virtually unobtainable by any other (cutting) process, even if cost were no object.

In a groove cut by the reflex-percussion process the edges of the groove tend to be strong, and the junction between the walls and the base of the groove can be at a sharply defined angle (generally a right-angle). The process is highly controllable. The process causes only a ~inimum of da~age in and around the groove cavity, both as regards the ~--` 20309~

avoidance of gross cracks, and also as regards the avoidance of micro~racturin~.

Notwithstanding these benefits of accuracy, the process is relatively fast: other methods of re~oving material from a groove of the above dimensions, such as the use of a jack hammerJ are much slower.

In the inventionJ the reflex-percussive prooess is essential for cutting the grooves. It is not essential that the cutting bit does not rotate. However, the resulting loss of accuracy, and slowness, when a rotating bit is used, make that variation of the process much less attractive, and it is therefore preferred that the bit be constrained against rotation. In explanation of this preference~ it ~ay be noted that when the bit does not rotate, as shown in CLARKE, the bit may be designed with a row of cutting teeth alon~
its edge, and it is this row which produces the side wall of the groove. When the bit rotates, there is not the same concentrated cutting action on the side walls.

In the invention, it is recognized that the ~roove which -results from the reflex-percussive process is accurate enough as regards the width of the groove to enable a preformed rubber strip to be inserted and securely held in the groove. If the groove were inaccurate, and if the attempt were made to fill the resulting irregularities and voids with adhesive or sealing compound~ it is recognized ~ .
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that the risk would be too high that the rubbsr strips ~ight work loose.

It is recognized also that the reflex-percussive process produces a groove which is wide enough to acco~odate a worthwhile width of rubber strip, for example 5 or 10 c~, as distinct from the thin, flimsy rubber strips which were all that could be acco~odated in saw-cut grooves. The depth of the groove preferably should be at least half its width.

The inventîon lies in the recognition of the usefulness of the reflex-percussion proc2ss for cutting the grooves for rubber rumble strips. It is recognized that the process provides wide, accurate grooves verY econo~ically, so ~uch ~-so indeed that it becomes economically practical to use - ~ -bulky pieces of rubber as the material for the strips.
Without the reflex-percussion process to cut the grooves, ~ ~
there ~ould be no economical way to make the groo~es - -accurate enough and wide enough; and without wide, acourately-cut grooves, large rubbsr strips cannot be used.

It ~ay be noted also that the accuracy of the depth of the groove is hardly less important than the accuracy of the width, and again, reflex-percussion gives an excellent degree of accuracy as re~ards the groove depth.

There are other ways of making wide, accurate grooves: for exa~pleJ by excavating a large trench, and filling the 2~fff~f~9~f~;

trfench with concrete into which the groovfs i5 ~oulded.
Ho~ever, such a procedure would out of the question on cost groundfs for rumble strips. It is possible to cut the two sidfe walls of a wide groove fairly accurately by using gan~ed saws, and by then re~oving the material between the saw cuts with a jack hamner. This prooedure, howevf-ffr, is not so econo~ical as reflex-percussion, and in any case the floor oP tlhe groove in that case cannot be controlled accurately.

The ability, with reflex percussion, to control the depth of the groove accurately, and the ability to obtain a s~ooth flat surface to the botto~ of the groove, are important contributing factors in the usefulness of the reflex- ;

percussion process in the invention.
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With the invention, ru~ble strips can be installed quickly and easily. The grooves are cut in one pass, and the strips are preforLed in the factory and are suitable for i~ediate on-site insertion into the grooves. If the grooves are arranged in the usual four groups, the lane need be closed ~for the work to be done) only for a few hours.

DETAILED DESCRIPTION OF PREFERRED EM~ODIMENT

By ~ay of further explanation of the invention, an exenplarY
e~bodi~ent of the invention will now be described with reference to the acco~panying drawingsJ in which:

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--- 2V309~)6 Fig 1 is a lateral cross-section across a lane oP a roadway in which a groove is being cut by a reflex-percussion ~achine;

Fig 2 is a section corresponding to that of Fig lA, showing the use of a diP~erent ~achine;

Fig 3 is a plan view showing one relationship of the cutting bits of the ~achine of Fig 1 to a groove;

Fig 4 is a view corresponding to Fig 3, showing an alternative relationship; :~

Fig 5 is a cross-section taken along the length of the roadway of a co~pleted groove, into which has been inserted a rubber strip;

Fig 6 is a section corresponding to Fig 5, showin~ a different rubber strip; : :
' Fig 7 is a seotion corresponding to Fig 5, showing another `~
for~ of the groove, and a different rubber strip;

Fig 8 is a lateral cross-section across the lane, corresponding to Fig 1, showing the co~pleted groove and inserted strip of Fig 7;

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Fi~ 9 is a section corresponding to ~ig 8, showing a dif~erent configuration o~ the lane.

The apparatus shown in the acco~panying drawings and described below are exa~ples ~which e~body the invention. It should be noted that the scope of the invention is defined by the acco~panYing clai~s, and not necessarily by speci~ic features o~ exe~plary e~bodiments.

Fig 1 shows two cutting heads of a reflex-peroussion groove-cutting apparatus 2J in the process of cutting a groove 3 across the width of a lane of a roadway.

The apparatus 2 is generally si~ilar to that sho~n in CLARRE. The construction and operation of one of the cutting heads 4 will now be described. A ha~mer 5 is grooved along its downward-facing surfaceJ and a series of bits 6, in the form of cross-bars, are let into the grooves, and are fixed therein. The ha~mer 5 is fixed to the nose 7 o~ a piston 8, in such a ~anner that, during operation, the ha~mer is unitary with the piston.

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The piston 8 is able to reciprocate in a cylinder 9, the cylinder being for~ed in a block 10. The piston 8 is provided with a head 12; the head is eccentric with respect to the rest of the piston, and is reciprocable in a comple~entary eccentric bore formed in the block 10. By virtue of the eccentric arrange~ent, the piston ~ay ~ -~ . .

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reciprocate freely in the cylinder, but the piston is constrained against rotation.

Ports are formed in the block 10; a pressure port 19, which is connected to a source of compressed air, and an exhaust port 16, which is open to the atmosphere. ~hen the piston is at the top of its stroke, ail from the port 14 flows into the annular space 18, through the hole 20 to the centre passage 23~ and into the chamber 25. The pressure then acts on the head 12 of the piston, driving the piston downwards.

The piston descends to the position shown in Fis 1. Now, air flows from the chamber 25, through the passage 23, through the hole 27, and out through the exhaust port 16.
Supply air enters the annular space 18, driving the piston back up~ and the reciprocating cycle is complete.
Typically, a reflex percussion hammer strikes 1400-1800 blows per minute.

It should be noted that, in accordance with the principles of ~eflex percussion, the piston (together with the hammer 5) does not bounce against the bottom of the groove 3: -~
rather, the piston is forcibly pulled clear of the groove just as the blow is struck.
' ' The shock wave from the blow travels into the material of the roadway, and is reflected back. But, when the shockwave l~ reflected ~ack to th~ ~ur~ace of the m~terl~l, there ls "

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no ~assive anvil present to resist the shockwave, and it is the resulting induced tension which ~ractures the material into small flakes or pieces.

It is the ~orced retraction of the piston which ensures that the hammer is olear be~ore the shock wave is reflected. In an apparatus such as a jack ha~er, where the anvil si~ply bounces clearJ it i5 in fact the re~lected shock-wave itself which causes the anvil to bounce. The mass of the anvil, ~hich is in contact with the material at that ~oment, abosorbs the returning shock wave and prevents tension being induced in the material. A jack ham~er cuts by a penetrating, crushing action: a reflex-percussion machine, by virtue of the ~orced withdrawal of th0 ham~er, cuts bY
inducing the ~aterial to ~racture itself.

In use, the block lO is located over the plaoe ~here the groove 3 is to com~ence, and the block is lowered until the ~ ~ -outtin~ bits 6 contact the surface of the roadway. As the block is lo~ered ~urther, the piston 8 is forced upuards;
reciprooatory vibration com~ences, and the bits start to cut down into the roadway. As the block descends still further, the other piston 29 is pushed upwards until the moment comes when it too starts to reciprocate. ~hen the cutting heads have cut down to the depth level shown in Fig 1, the descent o~ the block is checked, and the block is set to traverse horizontally to the right, thereby progressively cutting the groove.

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Preferably, the groove 3 is cut in a single pass. Thus, the bits 6 preeerably should extend aoross the ~ull width of the groove. However, in order to keep the mass of the hammers down, which is desirable in order to maintain a ~ast rate of reciprocation, the designer ~ay prefer not to have a bit ~idth o~ more than 5 cm. I~ the groove ~idth i8 to be 10 cm, the desi~ner may provide double the number o~
hammers, and arran~e them in stagg~red formation. Then, each hammer may be relativsly light, and each hammer has its o~n piston, and may reciprocate independently of the others.
Fi~s 3 and 4 show different ways of arranging the stagger o~
the bits relative to the groove, in cases where a stagger is re~uired~

Alternatively, when the cuttin~ head can be accuratelY
guided in its traverse, it is per~issible to cut a wide groove by taking two, or more, passes.

Fi~ 5 shows a rubber strip ~itted into the completed groove.
The grooves and strips are arranged in parallel, across the road, at the approach to a hazard, such as a road junction.
The rubber striP 30 is preformed, ~or example as an extrusion, having the same cross-section at all points along its length. The strip 30 may include holes 34, ~hich are included as part of its extruded form. The material of the strip 30 may be neoprene of the non-interconnected cell type.

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To install the rubber strip 30 in the groove 3, first the base 36 and walls 38 of the groove are liberally smeared with a suitable adhesive, or sealant/adhesive, material, preferably a one-part, moisture-curing, polyurethane and hydrocarbon solvent mixture. Then the strip is pressed down into the groove. The groove and strip should be oP
complementary widths, whereby the st~ip is a tight fit in the groove, and in fact has to be hammered in.

The rubber strip 30 is formed with a slightly convex upper surface 40, which is so dimensioned as to protrude slightly above the road surface after installation. Such holes 34 as :
are present are arranged so that the strip will have suitably resilient characteristics of depression when a tire rolls over the strip.

The strip 30 should not provide too much of an obstacle to a light vehicle such as a notor-cycle and yet the strip should provide sufficient intensity of rumble as to alert the driver of a heavy truck. By selecting a suitable grade of rubber, and by suitable dimensioning and positioning of the holes 34, the strip can be given a rate characteristic that is variableJ whereby a light load will easily de~lect the strip down to the level of the road surface 43, whereas a ~uch heavier load is needed to deflect the strip further down below the su~face.

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In the version shown in ~ig 6, a spacer 45 (made of metal, or a hard plastic) is includPd, the purpose of which is to allow the sprin~-characteristics of the strip 47 to be more accurately controlled.

In Fig 7, the rubber strip 49 is not held (or not held exclusively) by means of the sealant/adhesivs. In Fig 7, a channel 50 is cut into the floor 52 of the groove 3. The channal 50 preferably is also cut by the reflex-percussion process.

Into the channel 50, an anchor strip 54, made of aluminum for example, is secured by means of bolts 56. The bolts engage with the material of the roadway (asphalt, concrete, etc) and are of the self-expanding type.

The anchor strip S4 is formed with a Tee-shaped head S8, and the rubber strip 49 is formed with a complementar~ Tee-shaped slot.

The mechanical connection established by the interaction between the rubber strip and the anchor strip makes the strip even more secure within the groove than it was with the adhesive as previously described. It certainly is important that the rubber strip should never be allcwed to become detached from the groove, and the mechanical connection provides even greater security from that standpoint.

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The profile of the rubber strip 49 may be provided with holes, as at ~0, by means of which the deflection characteristics ~ay be opti~ized.

In the arrangement of Fig 7, the rubber strip has to be assembled by sliding khe strip onto the Tee-head 58 along the len~th of the strip, ie across the width of the road.
Access ~ust be provided at one end of the strip to enable assembly to be acco~plished in this way. Fig 8 sho~s how this may be done in the case of a country road with no sidewalk or kerbJ but where the side oP the road slopes away into a grass verge. The road surface 63 is generally a few centimetres above the level 65 of the verge, or it is in any event a si~ple matter to excavate the verge locally to provide acces~ to the (sloping) edge 67 of the asphalt or concrete.

As may be inPerred from Fig 1, when the operation of cutting the groove stops, the ri~ht hand end of the finished groove has a run-out, whereas the left hand end (ie the end of the groove which was formed first) is more nearly vertical.
Preferably, therefore, the groove should be started at the ~iddle of the road and should be cut towards the side o~ the road~ where the run out can be acco~odated. Thus, if in Fig 8 the groove is started at the end 69 near the ~iddle of the road, the end 69 can be al~ost sharply Yertical, and ~;
there~ore the rubber strip may be pushed almost to the very ;~

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end o~ the groove. The s~all space between the end of the rubber and the end 69 of the groove ~ay b~ filled with a suitable sealant and ~iller material.

The other end o~ the groove i5 at the side o~ the roadJ and the rubber ~ay be tri~med o~f to suit: again the space at the end o~ the groove is filled in with filler.

In the Fig 9 case, a kerb 70 is prssent at the side of the road. Therefore the groove cannot run out, as was ~ossible in Fig 8. The ri~ht hand end 74 of the groove h~s a ~uch ~ore gradual slope than the left hand end. There is no dif~ioulty in feeding the rubber strip onto the Tee-head fro~ the right hand endl since the strip is flexible enough to bend around the kerb. Again the ends of the groove, beyond the rubber, are filled in -- with a bulk filler such as asphalt if the voids are large enough.

When a snow plow blade strikes the rubber stripJ the i~pact is easily absorbed without either the strip or the blade being damaged. Th9 blade rises up slightly, and the strip descends sli~htly. The shock-absorbing nature of rubber, plus the fact that the rubber striP is wide and bulky, together with the ~act that the blade of a snow-plow is generally set at an angle so as to de~lect snow to the roadside, whereby the i~pact of ths blade does not occur all at once, co~bine to ~ake the rumble strips as described very easy to plo~.

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Although not called for ~y present standards, the rubber strips may be of a bright, evsn fluorescent, colour, to further alert a driver to the hazard. It ~ay be noted that the colouring would be ir,herent in the rubber, and would not be worn away. Th~ Pact that the upper surface Oe the rubber strip protrudes serves also to make the strips easily visible, especially in dark, wet contlitions, when any road marking that does not prctrude can be almost invisible.

Although the upper surfaces o~ the rubber strips have been shown as convex in the drawings, it is within the scope of the invention that the strips may be flat on top, and may be set flush with the road surface. This would reduce the rumble intensity~ and the visibility, but would render the strip even less liable to plowing problems, such as might arise for example in very cold conditions when rubber loses so~e of its flexibility.

The upper surface of the rubber strips ~ay be provided with a series of grooves. These would assist in conducting water away fro~ the surface, and would provide a measure of skid resistance.

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It ~ay be noted that in ~he rumble s~rips as described so~e s~all interval of time w~ll elapse from the ~o~ent a tire strikes the rubber until the rubber starts to descend, due ',: .
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to the hysteresis of the material. This delay would be totally insignificant if the strip were narrow, but, because the strip is some centimetrss wide, in the invention, the delay is suffioient that the rubber does not sink so quickly when the tire passes at a rapid speed, as uhen the tire passes slowly.

Therefore, a characteristic of the wide strip of the invention is that a rapidly travelling vehicle makes a louder noise than a slow vehicle, simply because the rubber cannot move aside very quickly. It is known that it is effective to place rumble strips progressively closer together, the nearer to the hazard, to ~ake it appear to the driver that he is going too fast: even more so with the invention, the vigour and intensity of the ru~ble alarm si~nal as created by a fast vehicle is considerably greater than that created by a slow vehicle.

It is contemplated, in the invention, that the rubber strip might alternatively be pre-set in a channell the channel being made of metal or hard plastic. The attachment of the rubber to the ~aterial of the channel could then be carried out in the factcry. The securin~ of the channel into the groove of course uould still have to be carried out in situ, but it is a less demanding task to produce, on the road, a good secure bond between the channel and the groove, than bstween the rubber and the groove. However, the provision of a channel would normally be re~uired only if the ~aterial : ~
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of the road were particularly soft, or in other adverse conditions.

In the ru~ble strip as described, the process by which the groove is cut involves traversin~ the cutting head along the length of the groove. The reflex-psrcussion process produces a groove in wllich the walls and base are very accurately defined, with strong edges; and in partioular, the junction between the walls and the base is accuratelY
defined. This ~eans that the rubber co~ponent may be made to fit very inti~ately into the wall-to-base iunction or corner. The result of this intimate corner-~it is that the strip has a great resistance to rotation of the rubber about an axis parallel to the length of the groove. The groove is disposed across the width of the roadway, which means that this high resistance applies to the ~ode of rotation in which the rubber ~ight work itself out of the groove, due to the long-ter~ action of traffic.

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Thus, in the invention, it is recognized that by usin~
reflex-percussion the rubber can be ~ade to fit very ~ -inti~ately into the corners between the walls and the base of the groove, and that therefore the rubber will have a great tendency not to rotate itself out of the groove. It is recognised that this resistance is utilized, in the case o~ a ru~ble strip running across the road, because the direction of the traffic is transverse to, and not parallel to, the direction of traverse of the cutting ha~er.

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-- ~o --It may be noted that the the rumble strip as described above is intended to extend across nearly the full width of a traffic lane, ie to be of about 3 metres in length. It is conte~plated, however, that the strip ~ay be shorter, and so~etimes ~ay be ~uch shorter. Such a short strip might be hardly longer than its width, and it should be understood that the ter~ rumble strip as used herein includes within its scope such a short rumble strip, which may rather be described as a ru~ble stud.

A ru~ble stud could be used as a between-lanes marker or delineator. As ~entioned, it is important that the direction of traverse of the reflex-percussion ham~er should lie transversly across the roadway, and not lie along the length of the roadway, and therefore the rumble stud should be so oriented that the (short~ groove is cut transverselY
across the width of the road, and not parallel to the length of the road. -Reflex-percussion is not an appropriate process for cutting strai~ht down, ie for drillin~ holes, or cutting a recess straight down, without a lateral traverse, into a body of concrete or asphalt, where the profile of the recess is the sa~e as the outline of the cutter. Reflex-percussion comes -~
into its own only when the cutting head is traversed in a direction parallel to the plane of the surface into which the recess is being made. ~hen cutting straight down, ie ,: - , . . .

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without traverse, the recess would tend to beco~e clo~ged with debris -- this ~ay be contrasted with the prooess o~
drilling such a recess, in which the drill-bit is provided with flutes for clearing the debris.

Thus, in reflex-percussion i.t is preferred that the outter be traversed across the surfaoe in order to cut tho reoess:
in the invention, it is preferred that the direotion of traverse should lie transverse to the length of the roadway;
and it is i~portant that these preferenoes be applied also in the case when the ru~ble strip is a ru~ble stud.

Preferably, therefore, the ru~ble stud takes the for~ of a short rubber strip inserted into a short reflex-percussion ~roove, where the groove was cut by an across-the-road traverse. In this case, the stud may be very secure, and is -~ I
able to stand up to years of service, including snow-plow~ ~:
action, without the rubber tending to work out of the groove due to repeated traffic contact.

It ~ight be considered that the ru~ble stud could be set in a groove which i5 cut by a reflex-percussion traverse that is directed not across, but along the length of, the roadway. But in such a case, the resulting ru~ble stud would be ~uch less secure, and that orientation of the strip is not preferred, in the invention.

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Claims (9)

1. CLAIM 1. A procedure for providing rumble strips in a roadway, comprising the steps:
   
   of providing a reflex percussion apparatus, having at least one piston and an associated hammer, which are arranged for rapid vibratory movement towards and away from the surface of the roadway so as to strike blows at a rapid rate on the surface of the roadway, wherein the apparatus includes a piston retraction means, operated by compressed air, for forcibly retracting the hammer clear of the road surface, substantially at the instant a blow has been struck;
   
   of cutting several grooves in parallel, laterally across the width of a traffic lane of the roadway, at the approach to a hazard, wherein each said groove is several centimetres wide;
   
   of providing strips of elastomeric material, one per groove, wherein each strip is of a width such that the strip is a tight fit in its respective groove;
   
   of providing a means for constraining the strips securely against working loose from their respective grooves;
   
   and of inserting and sealing the strips in their respective grooves.
2. CLAIM 2. Procedure of claim 1, wherein the apparatus includes a means for constraining the hammer against rotation.
3. CLAIM 3. Procedure of claim 2, wherein the hammer is provided with a plurality of outting bits in the form of bars, which extend across the width of the groove.
4. CLAIM 4. Procedure of claim 3, wherein the bars of one piston extend across only a portion of the full width of the groove, and of providing and arranging sufficient additional pistons in the apparatus that the bars in aggregate straddle the full width of the groove.
5. CLAIM 5. Procedure of claim 4, including the step of cutting the full width of the groove in a single pass of the reflex-percussion apparatus.
6. CLAIM 6. Procedure of claim 1, wherein the strip of elastomeric material substantially completely fills the groove, and protrudes slightly above the road surface.
7. CLAIM 7. Procedure of claim 1, wherein the strip of elastomeric material is of constant cross-sectional profile along its length, and wherein the strip includes a void or hole within the profile.
8. CLAIM 8. Procedure of claim 1, including the further steps:
   
   of providing an anchor strip, having a profile with an enlarged upper form, of providing fixing means for fixing the anchor strip securely within the groove;
   
   of providing a form in the profile of the elastomeric strip that is complementary to the form in the profile of the anchor strip;
   
   and of assembling the elastomeric strip lengthwise onto the anchor strip.
9. CLAIM 9. Procedure of claim 8, including the further steps of cutting a channel in the base of the groove, and of fixing the anchor strip in the channel.