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Patent Searching and Data


Title:
ROAD SAFETY BARRIER
Document Type and Number:
WIPO Patent Application WO/2014/207473
Kind Code:
A1
Abstract:
A coupling assembly (16) is provided for use in a road safety barrier to couple one or more longitudinally extending restraining members to a post member secured on or in the ground. The coupling assembly comprises an attachment member (22) for attaching the coupling assembly (16) to one or more restraining members and a coupling (24, 26) that couples the coupling assembly (16) to a post member). In the event of an impact of energy exceeding a first threshold, the coupling (24, 26) is configured to be linearly moveable from a first position to a second position to longitudinally displace the coupling assembly (16) and restraining members with respect to the post member to increase the height of the coupling assembly (16) and restraining members above the ground.

Inventors:
HARRIMAN MATTHEW (GB)
BOWYER STEVEN (GB)
PARDOE ANDREW (GB)
Application Number:
PCT/GB2014/051958
Publication Date:
December 31, 2014
Filing Date:
June 26, 2014
Export Citation:
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Assignee:
HILL & SMITH LTD (GB)
International Classes:
E01F15/04
Foreign References:
EP0708206A11996-04-24
EP1566486A12005-08-24
EP2204495A22010-07-07
FR2647824A11990-12-07
KR100654333B12006-12-08
Attorney, Agent or Firm:
OXLEY, Robin (Alpha TowerSuffolk Street Queensway, Birmingham B1 1TT, GB)
Download PDF:
Claims:
CLAIMS:

1. A coupling assembly (16) for use in a road safety barrier to couple one or more longitudinally extending restraining members to a post member secured on or in the ground, the coupling assembly comprising:

an attachment member (22) for attaching the coupling assembly (16) to one or more restraining members (14); and

a coupling (24, 26) that couples the assembly (16) to a post member; and wherein

in the event of an impact of energy exceeding a first threshold, the coupling (24,

26) is configured to be linearly moveable from a first position to a second position to displace the coupling assembly (16) and restraining members with respect to said post member, to increase the height of the coupling assembly (16) and restraining members above the ground.

2. The coupling assembly of claim 1 , wherein the coupling is linearly moveable in a direction substantially parallel to the post member.

3. The coupling assembly of claim 1 or 2, wherein the coupling is linearly moveable in a substantially vertical direction.

4. The coupling assembly of claim 1 , 2 or 3, wherein the coupling comprises an elongate slot (28) that extends substantially parallel to said post member. 5. The coupling assembly of any preceding claim, wherein the coupling comprises a substantially vertically oriented elongate slot (26).

6. The coupling assembly of claim 4 or 5, wherein the width of the slot is of substantially uniform width along the length thereof and further comprises a first opening at the upper end thereof and a second opening at the lower end thereof, the first and second openings having a dimension greater than the width of the slot.

7. The coupling assembly of claim 4 or 5, wherein the width of the slot is of substantially uniform width along the length thereof and further comprises a first opening at an upper end thereof having a dimension greater than the width of the slot.

8. The coupling assembly of claim 7, wherein the slot is open at the lower end thereof to form a slit in the coupling assembly. 9. The coupling assembly of any of claims 4 to 8, wherein the coupling further comprises a fastener (28) for attaching the coupling assembly to the post via the slot.

10. The coupling assembly of claim 9, wherein the coupling comprises a frictionally resistive component for resisting movement from the first position to the second position.

1 1. The coupling assembly of claim 9 or 10, wherein the fastener has a diameter or thickness that is greater than the width of the slot and is less than or substantially equal to the size of the first opening.

12. The coupling assembly of claim 9, 10 or 11 , wherein the fastener is a yieldable fastener that yields when energy from an impact exceeds a second threshold value to further longitudinally displace the coupling assembly (16) and restraining members (14) from and with respect to the post member (12) and further increase the height of the coupling assembly (16) and restraining members (14) above the ground.

13. The coupling assembly of any of claims 9 to 12, wherein the fastener is a bolt.

14. The coupling assembly of any preceding claim, wherein the attachment member (22) comprises a bridging element (22b) that contacts the upper end of the post member when the coupling is in the first position.

15. The coupling assembly of claim 14, wherein the width of the bridging element is greater than the cross-sectional dimension of the post member.

16. The coupling assembly of any preceding claim, wherein the attachment member comprises a projection or spigot (24) receivable within the upper end of the post member.

17. A road safety barrier comprising one or more longitudinally extending restraining members (14) supported at a height above the ground by one or more post members (12) secured on or in the ground and coupled thereto with a coupling assembly according to any of claims 1 to 16.

18. The barrier of claim 17, wherein the at least one or more restraining members comprise one or more rails, tubular rails or beams.

19. The barrier of claim 18, comprising a pair of rails, tubular rails or beams, one mounted to each side of the attachment member.

20. The barrier of claim 19, wherein the width of the bridging element defines the separation of the rails, tubular rails or beams. 21. A road safety fence post for use in a road safety barrier, comprising a post member securable on or in the ground, and the coupling assembly of any of claims 1 to 16, wherein the coupling couples the assembly to the post member.

22. A coupling assembly substantially as hereinbefore described with reference to Figures 1 , 3, 4 or 5.

23. A road safety barrier substantially as hereinbefore described with reference to Figure 2. 24. A road safety fence post substantially as hereinbefore described with reference to any of the Figures of the accompanying drawings.

Description:
Road Safety Barrier

This invention relates to road safety barriers, and in particular but not exclusively to road safety barriers of the type that employ one or more rails or beams.

Road safety barriers incorporating rails or beams as a vehicle restraining member comprise a series of spaced apart posts that are secured in or on the ground adjacent to the roadway for supporting the rails/beams. For the protection of the vehicle and its occupants, and other road users and nearby pedestrians, road safety barriers are required to restrain an impacting vehicle by arresting it and redirecting it, to prevent traversal of the barrier and encroachment into oncoming traffic or into the roadside.

The design and construction of road safety barriers depends on the type and level of containment required. For example, in order to restrain a heavy vehicle (e.g. a 10000kg truck), which can be tall with a high centre of gravity, it is necessary to configure the barrier to not only prevent it from breaching the barrier, potentially into oncoming traffic, but also from overturning.

Due to the variety of vehicles that are likely to be travelling on the road, the barrier system must be capable of restraining impacting vehicles ranging from small cars (typically 900kg) up to large vehicles weighing 10000kg or more. However, systems devised for restraining the latter may provide too much resistance and actually pose a danger to smaller, lighter vehicles. Furthermore, containment rails provided for restraining tall, heavy vehicles could be provided at too great a height, meaning smaller, lighter vehicles could pass underneath and not be contained.

A simple solution in the art provides barriers with a plurality of vertically spaced rails, although this inevitably increases the cost of the barrier installation. Systems such as those described in FR2647824 and FR2704012 show barrier systems having a pair of beams of W-cross-section supported by a series of posts. A vehicle impacting a proximal beam causes posts of the barrier to bend and, for high energy impacts e.g. from a large, heavy vehicle, the posts are bent to such an extent so as to force the distal barrier beams to the ground and, ultimately, for the fixing means joining the beams to the posts to break. Energy absorption during these processes assists in arresting and containing the vehicle. There is, however, little control over maintenance of the height of the barrier beams and small, light vehicles may be able to pass underneath the raised proximal beam and taller, heavier vehicles are likely to topple over the barrier beams. EP1619310 teaches a system having a spacer element that supports and spaces two W-cross section beams on a series of posts. In the event of an impact, the beam separates from the spacer element, and the spacer element separates from the posts, in order to maintain the position of the beam at the same height above the ground as before the impact.

In US5044609 and US5286137, the rails are supported on support members that can pivot about a fulcrum with respect to the post, and the support members are provided with weakened portions such that, in the event of an impact, the support members pivot causing a pin or suchlike to rupture the support member in the vicinity of the weakened areas and thus aid in absorbing energy from the impact. In the former, the configuration is such that the barrier height before and after an impact is maintained and, in the latter case, the rotation results in a proportional raising of the rail in order to restrain the impacting vehicle. These barrier systems are, however, clearly rather complex and thus difficult and expensive to manufacture, install and maintain. Such systems are also prone to malfunction or failure, e.g. in the event of an impact outside of the normally expected range, e.g. in terms of velocity, direction, energy etc.

The present invention has been devised with the foregoing in mind. In accordance with a first aspect of the present invention, there is provided a coupling assembly for use in a road safety barrier to couple one or more longitudinally extending restraining members to a post member secured on or in the ground as defined in claim 1. In the event of an impact by a car, the coupling assembly remains in the first position but, in the event of an impact by a larger/heavier vehicle, the coupling moves to the second position to still constrain and redirect the vehicle in the same manner, but also taking into account the larger dimensions thereof. Thus, advantageously, the coupling assembly enables road barriers to constrain and redirect impacting vehicles of varying masses, from small cars to large heavy multi-tonne vehicles through the provision of a simple, easy to manufacture, install and maintain mechanism.

Preferably, the coupling is linearly moveable in a direction substantially parallel to the post member or substantially perpendicular to the direction in which the road safety barrier extends. The coupling is therefore moveable in a substantially vertical direction for post members secured in the ground in a substantially upright position. Alternatively, if the post members are inclined with respect to the vertical, the coupling can be configured to be linearly moveable in a direction parallel thereto.

In an embodiment, the coupling comprises an elongate slot that extends substantially parallel to the post member. In an embodiment, the coupling comprises a substantially vertically oriented elongate slot. Preferably, the width of the slot is of substantially uniform width along the length thereof and further comprises a first opening at the upper end thereof and a second opening at the lower end thereof, the first and second openings having a dimension greater than the width of the slot. This provides a 'dogbone' shaped slot. In an alternative embodiment, the width of the slot is of substantially uniform width along the length thereof and comprises a first opening at the upper end thereof having a dimension greater than the width of the slot. Thus, the slot may have an enlarged opening only at its upper end. The lower end may be closed, or open to provide a slot in the form of a slit in the coupling member (to provide a 'keyhole' shaped slot or slit). In another alternative embodiment, the slot may have a width along its length that tapers toward the lower end thereof. In a further alternative embodiment, the slot may be profiled with formations. The formations may be frangible. In yet another alternative embodiment, the slot may be replaced with a line or series of apertures or perforations.

The coupling may further comprise a fastener for attaching the coupling assembly to the post via the slot. In a preferred embodiment, the attachment member comprises a projection or spigot receivable within the upper end of the post member. The slot is preferably provided within the spigot. In an embodiment, the coupling comprises a frictionally resistive component for resisting movement from the first position to the second position. The fastener may have a diameter or thickness that is greater than the width of the slot and is less than or substantially equal to the size of the first opening. Use of a slot and fastener advantageously provides a simple and easily maintainable mechanism for coupling longitudinally extending restraining members (e.g. rails or beams) of a road safety barrier to their supporting posts.

In an embodiment, the fastener is a yieldable fastener that yields when energy from an impact exceeds a second threshold value to further longitudinally displace the coupling assembly and restraining members from and with respect to the post member and further increase the height of the coupling assembly and restraining members above the ground. The fastener may be a bolt. The progression of the coupling from the first position to the second position, and then from the second position to a state where the bolt yields advantageously not only enables containment and redirection of a large, heavy vehicle, but further provides additional energy absorption and dissipation through the frictional resistance of the bolt within the slot and from yielding of the bolt.

The attachment member may comprise a bridging element that contacts the upper end of the post member when the coupling is in the first position. Preferably, the width of the bridging element is greater than the cross-sectional dimension of the post member. In accordance with a second aspect of the present invention, there is provided a road safety barrier comprising a plurality of road safety fence posts as defined in claim 17.

In an embodiment, the at least one or more restraining members comprise one or more rails, tubular rails or beams. Preferably, the barrier comprises a pair of rails, tubular rails or beams, one mounted to each side of the attachment member. The width of the bridging element defines the separation of the rails, tubular rails or beams.

A road safety barrier constructed in accordance with the embodiments described advantageously enables containment of vehicles of a range of sizes and masses without requiring complex mechanisms which would add to manufacture, installation, repair and replacement costs.

In accordance with a third aspect of the present invention, there is provided a road safety fence post for use with a road safety barrier having one or more longitudinal restraining members as defined in claim 21.

In any aspect, the posts may be hollow e.g. of circular, oval, square or rectangular cross-section, although it will be appreciated that posts of other cross-sections can also be used. For example, the post may have a C-, U-, S- or Z-shaped cross section. Alternatively, the posts could be solid, again of any shape and cross-section mentioned above or otherwise.

The invention will now be described by way of example with reference to the accompanying drawings, in which:

Figure 1a is a side view of a road safety barrier according to the present invention;

Figure 1 b is a front view of the road safety barrier of Figure 1 a;

Figure 2 is a perspective view of the barrier of Figure 1 a;

Figure 3 is an expanded perspective view of the spacer element of the road safety barrier of Figure 1 a;

Figures 4a to 4d are schematic views of an alternative embodiment employing a different slot and spigot; and

Figures 5a to 5c are side views of the barrier of Figures 1a and 1 b at various stages before and during impact.

Figures 1 a and 1 b show a road safety fence post 10 embodying the present invention, for use in a barrier 1 1 , e.g. as shown in Figure 2. The post 10 comprises a post member 12 that is adapted to be secured on or in the ground (not shown). The post member 12 is, in the embodiment shown, a hollow post e.g. of circular, oval, square or rectangular cross-section, although it will be appreciated that posts of other cross- sections can also be used. The post 10 is configured to support two rails 14. The rails 14 extend longitudinally with respect to the substantially vertical posts 12. The rails 14 are tubular rails, one mounted on either side of the post 10. In alternative embodiments (not shown), the rails 14 have alternative cross sectional shapes or could be beams (e.g. W-profile beam sections).

The rails 14 are attached to a coupling assembly 16. The coupling assembly is a bracket or spacer, which serves to maintain the two rails 14 at a predetermined separation, and to support the rails 14 on the post member 12. A fixing member 18 is provided (e.g. by welding) on the spacer 16 for attaching the spacer 16 to the rail. In the embodiment shown, the fixing member 18 comprises an elongate plate longitudinally oriented with the rail 14. The plate 18 is provided with a series of apertures 18a for receiving a bolt 20, which also passes through an aperture provided in the rail (not shown) to achieve attachment therebetween.

Using two rails 14 - one provided on either side of the posts 12 - advantageously provides strength to the barrier 11 , and containment for impacts from either side of the barrier 11. In an alternative embodiment, a single rail could be provided on one side only of the post 10, or a plurality of rails (spaced vertically and/or horizontally) could be provided on each side of the post 10.

The coupling assembly 16, rails 14 and posts 12 are preferably made of steel, but it will be appreciated that other materials could be used.

As shown in Figure 3, the spacer 16 comprises a bridge member 22. In the embodiment shown, the bridge 22 is a sheet of material formed or bent into an inverted 'U' shape. The two legs 22a of the 'U' shape provide attachment surfaces or edges for the rails 14 as described above. Although not shown in Figure 3, an aperture may be alternatively be provided within the U-legs 22a for attachment via an aperture in the rail 14 again with a bolt or other suitable fastener. The width x of the top 22b of the bridge 22 (plus the thickness of the fixing members 18, if used) thus defines the separation of the rails 14. The width x of the bridge 22 is greater than the width y of the post member 12, to enable the bridge 22 to be supported on top of the post member 12 at end 12a thereof.

The spacer 16 comprises a spigot 24 that projects downwardly from the bridge member 22. The bridge 22 and spigot 24 may be formed as a unitary component, or may be fixed (e.g. welded or bolted) together. The spigot 24 projects downwardly from the bridge 22 and has a width z less than that y of the post member 12, such that it can be accommodated within confines of the hollow post member 12. The cross-sectional shape of the spigot 24 is preferably, but not necessarily, the same as that of the post member 12. Thus, in the embodiment shown, the spigot 24 and post 12 are of a circular cross section. The spigot 24 is hollow, but may be solid in alternative embodiments. Spigots of other cross sections could also be utilised, for example the spigot 24 may be a flat plate or thicker solid projection. The spigot 24 comprises a longitudinally extending slot or opening 26. As such, the slot 26 extends substantially vertically. One slot 26 is visible in Figures 1 a, 3 and 5 although it should be noted that a further slot 26 is provided in the spigot 24 at a position on the spigot diametrically opposite. In an alternative embodiment, just a single slot is provided.

The slot 26 has a width that is substantially uniform along its length 26a, widening into a first, upper larger opening 26b and a second, lower opening 26c at its ends. The slot 26 thus has a 'dumbbell' or 'dogbone' type shape. A fixing bolt 28 is provided to extend through an aperture 29 provided in the post member 12 and the upper opening 26b, and is externally secured with a nut 30, as shown in Figures 1 b and 3. The diameter of the fixing bolt 28 is substantially equal to or slightly less than the size of the openings 26b, 26c, but slightly greater than the width 26a of the slot 26. This will provide for frictional resistance to movement of the bolt 28 within the slot 26 as will be described in greater detail below.

In the embodiments described above, the slot 26 has a dumbbell shape, with a consistent width 26a along the length thereof and larger apertures at each end thereof 26b, 26c. In an alternative embodiment, the slot may only have an enlarged opening 26b at its upper end. Figures 4a to 4d show an alternative arrangement for a slot and spigot that can be utilised instead of the dumbbell shaped slot shown in Figures 1 , 3 and 5 and discussed in relation thereto. All other features are as previously shown and described, and features in common with the previously described embodiment remain unchanged.

Referring first to Figure 4a, the spigot 24 again comprises a longitudinally extending slot or opening 26' that extends substantially vertically. The slot 26' has a width that is substantially uniform along its length 26a, widening into a first, upper larger opening 26b. The slot 26' extends fully to the lower edge of the spigot 24. As such the lower end 26d of the slot 26' is open so as to provide a slit in the spigot 24. The geometry of the slit 26' is shown in Figure 4b.

As can be seen from Figures 4c and 4d, the slot 26' extends through the spigot 24 such that diametrically opposite surfaces of the hollow spigot 24 each comprises a slot 26'. Alternatively, just a single slot 26' may be provided. Alternatively, the spigot 24 could comprise one closed-ended slot 26 and one open-ended slot 26.

As previously described, a fixing bolt 28 is provided to initially extend through an aperture 29 provided in the post member 12 and the upper opening 26b, and is externally secured with a nut 30, as shown in Figures 1 b and 3.

In another alternative embodiment, the slot 26 may have a width along its length 26a that tapers toward the lower end thereof, in order to provide further frictional resistance to movement of the bolt 28 therethrough. In another alternative embodiment, the slot could be profiled with formations that offer resistance to passage of the bolt therethrough. The formations may be frangible. In another alternative embodiment, the slot 26 may be replaced with a line or series of apertures or perforations such that, in the event of an impact of sufficient energy, the bolt 28 travels through the perforations tearing the material of the spigot therebetween as an energy absorption mechanism.

Referring again to the first embodiment, Figure 5a is identical to Figure 1a, and shows the arrangement of the components in a first position representing the 'initial' or 'nonimpact' state of the post 10. In this first position, before any impact by a vehicle has occurred, the fixing bolt 28 is located within the upper opening 26a of the spigot slot 26 and the bridge 22b of the spacer 16 sits upon the upper end 12a of the post member 12 as previously described.

Figure 5b shows the post 10 in the event of an impact of by a vehicle on the post 10 or barrier 11. In this second state, the energy from the impact exceeds a first threshold. In this second state, the force from the impact has been sufficient to urge the rails 14/spacer 16 unit upwards, and the fixing bolt 28, which is initially located in the upper opening 26a is transferred to the lower opening 26b. In this position, the bridge member 22b has been separated from the top 12a of the post member 12 such that it no longer sits or rests thereon. Since the diameter of the fixing bolt 28 is less than the width 26a of the slot 26, passage of the bolt 28 through the slot 26a is subject to frictional resistance, which assists in absorbing energy from the impact and which, in turn, assists in restraining the impacting vehicle on the carriageway. If the impact energy is great enough, the barrier 10 will enter a third state, as shown in Figure 5c. Here, the energy from the impact exceeds a second threshold. Here, the energy from the impact has been sufficient to force the fixing bolt 28 along the entire length of the slot but, since the yield strength of the bolt 28 is less than that of the material of which the spigot 24 is made, the bolt 28 yields or shears. This enables further upward movement of the spacer/rail unit 14, 16, relative to the post member 12, and release of the spacer 16 from the upper end 12a of the post member 12. The yield strength of the bolt 28 is a known parameter, calculated from factors such as the material composition and dimensions of the bolt 28 and post member 12, and can thus enable separation of the bracket 16 from the post member 12 at a calculable, predetermined impact energy.

Due to the inherent strength of the barrier 1 1 , e.g. due to the provision of two steel rails 14, the arrangement provides for a vehicle up to 1500kg (e.g. an average sized car) to be contained and redirected without the lifting/separating mechanism coming into play. That is, in the event of such an impact, the bridge member 22 will remain in contact with the upper end 12a of the post member 12. Consequently, the vehicle is also prevented from travelling underneath the barrier 1 1. (The beams 14 may typically be provided at a 'standard' height corresponding to the height of the bumper of an impacting car, e.g. approx. 610mm.) For vehicles in excess of 1500kg the spigot slot 26 is designed to travel vertically upward and around the connecting bolt 28, coming to rest such that the bolt 28 is located in the lower hole 26c of the spigot 28, resulting in a rising mechanism that counteracts overturning of a heavier vehicle, and hence reducing its lean. The bolt will then shear (Figure 5c), if the impact energy is great enough, releasing the post 12a from the beams 14, to prohibit the deflecting post 12 from pulling the barrier 11 down and allowing the vehicle to mount the barrier 11.

In the alternative embodiment of Figures 4a to 4d, when the barrier 1 1 is impacted by a small vehicle (e.g. a typical car), the bolt 28 will remain located in the upper aperture 26b before sliding down the slot 26', due to the small impact loading on the barrier. However, when a heavier vehicle (e.g. a multi-tonne truck) impacts the barrier 1 1 , the bolt 28 will travel down the slot 26' almost immediately due to the comparatively higher impact loading on the barrier, raising the height of the beam 14 and thus resisting overturning of the vehicle that might otherwise occur due to the higher centre of gravity of the larger vehicle.

The barrier 11 has thus been designed, and the arrangement calculated, based on years of experience with this field of engineering, so that the bolt 28 will yield when the force of an impact reaches a particular threshold, to purposefully break the connection between the rails 14 and the posts 10. Restraining capabilities will be maintained, due to the rail 14 being connected to other rails and adjacent rails and the posts on which they are supported will ensure integrity of the barrier in the event of an impact. Separation further ensures that the integrity of parts of the barrier arrangement away from the vicinity of the impact is maintained, thus minimising the repairs required after an impact.

Importantly, the upward movement of the rail 14 relative to the post 12 in the event of an impact enables containment of heavy/tall vehicles to be achieved. This is because the increased height of the barrier 11 in the event of an impact is more effective at preventing a tall vehicle from overturning because the centre of gravity of the vehicle is no longer precariously above the height of the barrier 1 1.

By way of an example, as a result of a 10000kg lorry impacting the barrier, the impact energy will be sufficient to force the post 10 from the first state (Figure 5a), through the second state (Figure 5b) to the third state (Figure 5c). I.e. both the first and second energy thresholds are exceeded. However, the energy absorbing capabilities of the post 10/barrier 1 1 - due to the frictional resistance of the bolt 28 travelling through the slot 26 and subsequent shearing of the bolt 28 - are sufficient to restrain the vehicle on the carriageway. By contrast, an average sized car impacting the post/barrier would not provide sufficient energy to reach the third stage. Here, as described above, the first impact energy threshold is not reached.