GB2381285A

GB2381285A - Traffic calming device

Info

Publication number: GB2381285A
Application number: GB0125085A
Authority: GB
Inventors: John Lay; Martin Ashfield
Original assignee: RMC AGGREGATES
Current assignee: RMC AGGREGATES
Priority date: 2001-10-18
Filing date: 2001-10-18
Publication date: 2003-04-30
Anticipated expiration: 2021-10-18
Also published as: GB2381285B; GB0125085D0

Abstract

A device for attachment to a road or carriageway comprises a solid mass made from aggregate and a binder material preferably asphalt or bitumen. The device may be a preformed portion of a speed cushion or a road hump, where two or more devices are attached to the road to form a discreet traffic calming obstacle. The surface of the device is skid resistant. The device is made using a mould into which is placed a heated mixture of aggregate and binder. This mix is allowed to harden and is then removed from the mould. To lift the device, attachment points are provided in the form of removable lifting eyes. The device can then be readily transported to the location for installation, where it can be easily handled into place after adhesive is applied to the road surface or the device itself. The adhesive used is preferably a rapid curing resin such as polyurethane.

Description

Traffic Calming Device The present invention relates generally to the field of traffic calming devices and, in particular, to road humps and speed cushions.

A speed cushion is a form of road hump, occupying part of the traffic lane in which it is installed.

They were first installed on the public highway in the UK in 1993 as an alternative to flat and round top road humps.

The major difference between a road hump, and a speed cushion is that the hump is positioned transversely across the full width of the carriageway, whereas cushions are positioned usually in pairs within the carriageway width, with small gaps in between.

The speed cushion was developed in response to a number of concerns with regards to road humps from bus companies and emergency services. Their main concerns were that of delay and discomfort, and a lengthening of response times for emergency vehicles as they slow down over the humps.

Speed cushions overcome these problems to some extent in that they allow wider wheel base vehicles such as buses to bridge the cushions, thus causing little delay or discomfort. They also allow emergency vehicles to either bridge, or pass between the cushions with little effect on response times.

Speed cushions also allow cyclists and motorcyclists to pass through the gap near to the kerb, thus not causing discomfort or possible hazards

when passing over the top of them.

The concerns over the use of other speed calming systems such as road humps and sleeping policemen, have also led to many such existing systems being replaced by cushions.

Speed cushions are mainly used in built up areas and, in particular, routes leading into towns. Routes in the vicinity of schools and shopping centres also tend to be regulated by speed cushions.

The major concern over the speed cushion system lies in the drivers'tendency to aim for the gap between cushions, thus creating a hazard to other vehicles approaching in the opposite direction.

Solutions to this problem which have been tried are to position a central island between two humps, or to use a three cushion system with smaller gaps separating them.

The current legal position is that the Highways (Road Humps) Regulations (1996) make it unnecessary to seek any special authorisation for speed cushion design, however authorisation for associated markings is necessary (Traffic Signs Regulations and General Directions 1994).

In 1992, track trials, and subsequently on road monitoring tests, were carried out by the Transport Research Laboratory on behalf of the Driver Information and Traffic Management Division of the Department of the Environment, Transport and the Regions (DETR). The study investigated various speed cushion designs and as a result the TRL was able to give recommendations for speed cushion dimensions:

(a) Side ramp gradients not steeper than 1: 4 ; (b) Off/on ramps not steeper than 1 : 8 (curved on/off ramps should have an average gradient not steeper than 1: 5); (c) A maximum height of 80mm (though 75mm has since been found to be preferable); (d) A maximum length of 3700mm (with a minimum plateau length of 800mm to prevent grounding); and (e) A maximum width of 2000mm (for bus routes a width of between 1600mm and 1700mm is preferred).

A number of speed cushion designs are currently used throughout the UK. These include pre-constructed rubber cushions, which are bolted directly on to the road surface, pre-formed concrete cushions, and block paviour construction. These methods have their benefits, however noise and skidding resistance, are particular problems.

The most commonly used mode of cushion construction is that of in situ forming of high stone content bituminous material. This involved planing out the area upon which the cushion is to be constructed in order to provide a key and a firm foundation. The area is then sprayed with a tack coat and the hot asphalt formed using a mould, before being compacted with small rollers and/or vibrating plate compactors to achieve the required shape. The material must then be left to cool before the markings are added and the cushion subjected to traffic. The major problem with this method is one of time as each cushion takes approximately 3-4 hours to construct from planing to completion.

The present invention aims to address at least some of the problems associated with the prior art.

Accordingly, in a first aspect the present invention provides a device for attachment to a running course for the purpose of traffic calming, wherein, in use, said device raises a portion of the running course, and wherein said device is formed into a substantially solid mass comprising aggregate and a binder material prior to its attachment to the road surface.

The device will generally be an integrally preformed speed cushion or road hump, although the present invention is also intended to encompass any speed calming device which acts by raising a portion of the running course.

In an alternative embodiment, the device is a preformed portion of a speed cushion or road hump for combination, in use, with one or more such portions to form a speed cushion or road hump.

The running course will typically comprise a wearing surface overlying a base course and examples include road and carriageways.

The device is preferably preformed from a composition comprising aggregate and a binder comprising one or both of asphalt and/or bitumen.

Asphalt is a name given to various bituminous substances and typically comprises a semisolid mixture of several hydrocarbons. In the road building industry the term asphalt material is often also taken to mean a material comprising aggregate and a bitumen binder.

The aggregate may comprise coarse and/or fine aggregate and typically comprises one or more of

stone, sand and/or filler. An example of a suitable filler is limestone. The filler will typically have a particle size of 75 um.

An adhesive coating is advantageously provided on at least a portion of the device for the purpose of adhering the device to the running course. A particularly preferred adhesive comprises a curing resin (preferably a rapid curing resin) and optionally a fine aggregate such as sand. The adhesive may, of course, include more than one resin. A preferred resin is polyurethane.

Advantageously, the device is provided with means for facilitating lifting of the device. Such means may comprise, for example, one or more attachment points and/or one or more straps, preferably sacrificial straps. For example, one or more lifting eyes may be provided. The means for facilitating lifting of the device is preferably removable so that the device can be lifted and set into place on the running course, and the means subsequently removed.

Advantageously, the device is preformed from a composition comprising aggregate and a binder of asphalt and/or bitumen. This preferably has anti-skid properties. Irrespective of the material from which the device is formed, the device is preferably provided with a skid-resistance surface.

The present invention also provides a road or carriageway comprising a device as herein described, said device being attached to the road or carriageway by means of an adhesive. The adhesive preferably comprises a curing resin (more preferably a rapid curing resin) and optionally a fine aggregate such as

sand. The adhesive may include more than one resin.

A preferred resin is polyurethane.

The terms adhesive and bedding compound as used herein are interchangeable. In other words, the adhesive may act as both an adhesive and a bedding compound.

In a second aspect, the present invention also provides a method of installing a traffic calming device in a running course, the method comprising: (a) providing a device as herein described; and (b) attaching the device to the running course.

An adhesive coating as herein described may be provided on a surface of the device and/or the running course to thereby attach the device to the running course.

In one embodiment, two or more devices are attached to the running course and so arranged to form a discrete traffic calming obstacle. In this case, the two or more devices may be adhered to one another by mean of an adhesive/bedding medium as herein described.

In a third aspect, the present invention provides a method of manufacturing a device as herein described, the method comprising: (i) providing a composition comprising aggregate and a binder material, said composition being provided in a pre-hardened state; (ii) providing a mould having a shape that conforms or substantially conforms to the shape of the device ; (iii) filling the mould with said composition;

(iv) allowing said composition in said mould to harden; and (v) removing the hardened composition from the mould to produce said device.

The composition in the pre-hardened state is able to fill and substantially conform to the shape of the mould. The composition in the pre-hardened state will typically be a viscous material which flows on the application of a shear force.

The composition preferably comprises aggregate and a binder comprising one or both of asphalt and/or bitumen. To achieve the pre-hardened state such a composition is heated. The composition may be described as a thermoplastic material in that it flows when hot. On cooling, the composition hardens. As will be appreciated, the aggregate may comprise coarse and/or fine aggregate and typically comprises one or more of stone, sand and/or filler.

The method may further include the step of applying an adhesive coating as herein described to a surface of the device.

The method may further include the step of attaching the device to a running course.

The present invention will now be described further, by way of example, with reference to the following drawings in which: Figures la and b are schematic illustrations of a speed cushion made according to one embodiment of the present invention.

Figure 2 is a schematic illustration of a speed cushion made according to the present invention with a lifting eye mechanism.

Figures 3a and b are schematic illustrations of a speed cushion made according to a further embodiment of the present invention.

Figure 4 is a schematic illustration of a plurality of speed cushions arranged on a carriage way.

The following discussion relates to speed cushions, but is intended to apply equally to other traffic calming devices encompassed by the present invention such as, for example, speed humps.

The present invention provides a method of manufacturing and installing speed cushions, whereby the cushion is manufactured away from the site, and can be installed as a single unit within the carriageway.

The'off site'manufacture of the cushion prevents carriageway closure for a prolonged period. The current installation method using hot bituminous material often causes a carriageway closure of up to five hours. The use of a rapid cure resin (for example an adhesive comprising one or more polyurethane resins) to fix the cushion to the road surface also helps to prevent unnecessary delay.

The preferred use of a rapid curing resin bedding compound allows the cushion to be mounted directly on to the current road surface and thus prevents the need for costly and time consuming planing of the cushion

area.

The present invention also addresses the problem of uniformity which is apparent in current in situ formed asphalt cushions. By compacting the material into moulds each cushion will be of substantially the same dimensions.

The cushion is preferably constructed in segments (usually quarters) and preferably from asphalt material (for example 35/14 or 55/14 HRA) using 50 Penetration Bitumen (for example 40/60 grade).

The segments are made to the required dimensions by compacting hot material into metal moulds which are then removed once the material has cooled.

Each segment is preferably fitted with a lifting eye and/or strap (s) (preferably sacrificial strap (s)) which enables them to be transported and positioned using mechanical lifting equipment.

The cushions may then be marked to the agreed specification using, for example, a pigmented resin (eg a polyurethane resin).

The cushion segments may be fixed directly on to the original carriageway using a bedding compound. A bedding compound may also be used to bond the segments together. The bedding compound is preferably a durable and flexible material which can withstand the high loading stresses created by heavy vehicles. A particularly preferred bedding compound comprises one or more rapid curing resins, optionally together with a fine aggregate such as sand. An example of a rapid curing resin is a polyurethane resin. It will be

appreciated that the bedding compound may act both as a bedding medium and an adhesive.

Figures la and b show a speed cushion according to the present invention. Typical dimensions are indicated by way of example.

The cushions may be manufactured as an integral body or, alternatively, in segments, for example four quarters. In the latter case, a separate steel mould may be used for each segment or quarter. The moulds are manufactured in order that when the cushion segments are bedded together with the resin compound, they are of substantially the same dimensions, as shown in Figures la and b.

The moulds are placed upside down and supported at the sloped edges in order for the compaction of the material to be uniform. The moulds are preferably provided with a release agent (for example a light grease) to aid the de-bonding of the asphalt from the mould sides.

The moulds are preferably fitted with a lifting eye which passes through the finished cushion and supports its base (see Figure 2). This is designed so that it may be extracted once the mould is positioned on to the bedding compound on site. Alternatively, or in combination, one or more straps (preferably sacrificial straps) (not shown) may be added once the cushion or segment thereof is removed from the mould.

A hot asphalt material (i. e. a material comprising bitumen and aggregate) is placed in the mould and preferably compacted using, for example, a combination of a plate compactor and a vibrating

hammer fitted with a square foot. The vibrating hammer is used as particular attention is needed when compacting material into the mould corners. It may also be used to'finish off'the compaction procedure.

The cushion segments are typically left to cool in the moulds to ambient temperature overnight. The moulds may then be turned using a mechanical lifting device and then removed from the segments.

The cushion segments may then be loaded on to pallets and placed on a lorry fitted with a mechanical lifting arm which is capable of lifting the segments into position on the road or carriageway.

The position of the required cushion is preferably marked on the present road surface prior to the installation of the cushion unit.

The area for the cushion may be surrounded by a rectangular frame, which may be used to provide a uniform thickness of the bedding material. It also enables any irregularities in the road surface to be overcome.

The bedding material is then mixed using, for example, a mechanical mixer such as a cretangle mixer in order for the resin components to be thoroughly and quickly mixed together with the sand.

The bedding frame is then filled with the bedding material and levelled to the top of the frame to give a bed thickness of approximately 10 mm.

The segments of the cushion are then lowered on to the bedding material using the mechanical lifting

arm. Once all four segments are in position the bedding frame is removed along with the lifting eyes from each segment.

If present, the joint between the segments and the voids left by the lifting eyes may then be filled with a more fluid resin and sand mix which then bonds them together and prevents any ingress of water.

Alternatively, or in combination, the sacrificial straps (if present) may be removed.

The edges of the cushion are sealed to the road surface by a'toe'of bedding compound which finishes off the ramped sides.

Finally, the cushions are marked with the appropriate road markings using, for example, a pigmented resin, preferably a polyurethane resin.

The resin will typically be left to cure for thirty minutes before the cushion is opened to traffic.

The cushions may be placed in pairs across the carriageway, typically between 60 and 100 metres apart.

A further embodiment of the present invention will now be described with reference to Figures 3 and 4. This embodiment is based on the same concept of off site manufacture, and rapid installation.

This embodiment brings together the speed cushion concept and the rumble strip system commonly used on entrance roads into towns and villages. It is best suited to roads where a 20 mph speed limit is to be

enforced, such as near schools and shopping centres.

With reference to Figure 4, the overall unit consists of a number of smaller individual cushions which are positioned in the carriageway to create a pattern which significantly reduces the speed of cars.

The pattern also enables larger wheel base vehicles such as buses, and more importantly fire engines and ambulances, to straddle the cushions and thus not reduce response times and ride quality.

The small cushions are manufactured away from site in steel moulds in the same manner as described above.

The cushions may then be transported to site, and fixed directly onto the carriageway using the resin based material (preferably as herein described) in the required pattern.

This embodiment offers a number of advantages, including: (i) Individual cushions can be manufactured off site; (ii) The manufacturing process requires no specialist equipment for handling; (iii) The number which can be manufactured is much higher than the complete cushion system; (iv) The height of the cushions can be adjusted to suit particular contracts without the need for expensive larger moulds; (v) The small cushions are easily transported, removing the need for a lifting arm; (vi) The cushions can be placed by hand; (vii) The amount of bedding required is much less than with the larger cushions;

(viii) The installation procedure is quick and much more adaptable to the carriageway profile; (ix) The markings can be added prior to installation; (x) The units can be positioned to suit any carriageway width; (xi) The installation is rapid and requires little lane closure; (xii) The units can be removed by, for example, planing and/or using a jack hammer, to facilitate resurfacing; (xiii) The traffic is slowed down further by the lower ride quality at high speed than with the cushion system; (xiv) The tendency for drivers to aim between the cushions at higher speeds in the centre of the road is reduced, as the ride quality would be poor even with only two wheels travelling over the cushions; (xv) The length of the unit can be tailored depending on the application.

Claims

CLAIMS : 1. A device for attachment to a running course for the purpose of traffic calming, wherein, in use, said device raises a portion of the running course, and wherein said device is formed into a substantially solid mass comprising aggregate and a binder material prior to its attachment to the road surface.
2. A device as claimed in claim 1, wherein the device is an integrally preformed speed cushion or road hump.
3. A device as claimed in claim 1, wherein the device is a preformed portion of a speed cushion or road hump for combination, in use, with one or more such portions to form a speed cushion or road hump.
4. A device as claimed in any one of the preceding claims, wherein the device is for attachment to a running course which comprises a wearing surface overlying a base course.
5. A device as claimed in any one of the preceding claims, wherein the device is for attachment to a running course which is a road or carriageway.
6. A device as claimed in any one of the preceding claims, wherein the device is preformed from a composition comprising aggregate and a binder of asphalt and/or bitumen.
7. A device as claimed in any one of the preceding claims, wherein the aggregate comprises one or more of stone, sand and/or filler.

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8. A device as claimed in any one of the preceding claims, wherein an adhesive coating is provided on at least a portion of the device for the purpose of adhering the device to the running course.
9. A device as claimed in claim 8, wherein the adhesive coating comprises a curing resin (preferably a rapid curing resin) and optionally a fine aggregate such as sand.
10. A device as claimed in claim 8 or claim 9, wherein the adhesive coating comprises a polyurethane resin and optionally a fine aggregate such as sand.
11. A device as claimed in any one of the preceding claims, wherein the device also includes means for facilitating lifting of the device.
12. A device as claimed in claim 11, wherein said means for facilitating lifting of the device comprises one or more attachment points and/or one or more straps (preferably sacrificial straps).
13. A device as claimed in claim 12, wherein the one or more attachment points comprise one or more lifting eyes.
14. A device as claimed in any one of claims 11 to 13, wherein said means for facilitating lifting of the device is/are removable.
15. A device as claimed in any one of the preceding claims, wherein the device is provided with a skidresistant surface.
16. A road or carriageway comprising a device as

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defined in any one of claims 1 to 15, said device being attached to the road or carriageway by means of an adhesive comprising a curing resin (preferably a rapid curing resin) and optionally a fine aggregate such as sand.
17. A road or carriageway as claimed in claim 16, wherein the curing resin comprises one or more polyurethane resins.
18. A method of installing a traffic calming device in a running course, the method comprising: (a) providing a device as defined in any one of claims 1 to 15 ; and (b) attaching the device to the running course.
19. A method as claimed in claim 18, wherein an adhesive coating is provided on a surface of the device and/or the running course to thereby attach the device to the running course.
20. A method as claimed in claim 19, wherein the adhesive coating comprises a curing resin (preferably a rapid curing resin, more preferably a polyurethane resin) and optionally a fine aggregate such as sand.
21. A method as claimed in any one of claims 18 to 20, wherein two or more devices are attached to the running course and so arranged to form a discrete traffic calming obstacle.
22. A method as claimed in claim 21, wherein said two or more devices are adhered to one another by mean of an adhesive medium.
23. A method as claimed in claim 22, wherein the

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adhesive medium comprises a curing resin (preferably a rapid curing resin, more preferably a polyurethane resin) and optionally a fine aggregate such as sand.
24. A method of manufacturing a device as defined in any one of claims 1 to 15, the method comprising: (i) providing a composition comprising aggregate and a binder material, said composition being provided in a pre-hardened state; (ii) providing a mould having a shape that conforms or substantially conforms to the shape of the device; (iii) filling the mould with said composition; (iv) allowing said composition in said mould to harden; and (v) removing the hardened composition from the mould to produce said device.
25. A method as claimed in claim 24, wherein the binder in the composition comprises asphalt and/or bitumen.
26. A method as claimed in claim 24 or claim 25, wherein the composition is heated to achieve the prehardened state.
27. A method as claimed in any one of claims 24 to 26, wherein the aggregate comprises one or more of stone, sand and/or filler.
28. A method as claimed in any one of claims 24 to 27, further including the step of applying an adhesive coating to a surface of the device.
29. A method as claimed in any one of claims 24 to 28, further including attaching the device to a

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running course.
30. A device for attachment to a running course for the purpose of traffic calming substantially as hereinbefore described with reference to any one of the drawings.
31. A device for attachment to a running course for the purpose of traffic calming as claimed in any one of claims 1 to 15 and substantially as hereinbefore described.