GB2383362A

GB2383362A - Apparatus for connecting a wire rope safety barrier to a beam safety barrier

Info

Publication number: GB2383362A
Application number: GB0130259A
Authority: GB
Inventors: Bryan Deacon
Original assignee: Brifen Ltd
Current assignee: Brifen Ltd
Priority date: 2001-12-18
Filing date: 2001-12-18
Publication date: 2003-06-25
Anticipated expiration: 2021-12-18
Also published as: GB2383362B; GB0130259D0

Abstract

The apparatus, for connecting a first safety barrier portion 1 formed with at least one wire rope to a second safety barrier portion 2 formed with at least one corrugated beam 9a,9b or box-section, comprises attachment means for attaching at least one wire rope to at least one beam so that tension in the wire rope is transferred to the beam section of the barrier with the wire rope and the portion of the beam barrier adjacent the wire rope barrier being constrained to move together in a sideways direction but being relatively movable lengthwise. The apparatus may include a deflector 21 that covers the end of the beam barrier facing the wire rope barrier, with the deflector having a fixing portion adapted to be connected to the beam barrier and a deflecting portion which is bent relative to the wire rope. The attachment means may comprise at least one holder through which the wire rope passes and at least one anchorage for connecting the wire rope to the beam barrier at a location remote from the end portion of the beam barrier. The anchorage may be adapted to receive an end termination of the wire rope. A third section of barrier 3 may be included after the beam barrier portion which comprises at least one beam 12 which is more rigid than that in the second safety barrier portion.

Description

HIGH INTEGRITY TRANSITION FOR SAFETY BARRIERS This invention relates to safety barriers, in particular for use at the sides or central reservations of roads and motorways.

Known safety barriers include beam-type safety barriers including, for example, a corrugated beam or a box-section beam. Another known safety barrier is a wire rope safety fence, including at least one wire rope maintained under tension; a preferred fence is described in GB-A-2 224 528.

Safety barriers differ in their compliance, depending on the details of their design and construction. The wire rope safety fence is understood to act as a cushion, offering an initially low resistance to penetration by an errant vehicle, the restoring force increasing progressively as the vehicle penetration proceeds. This characteristic is very effective at minimising the deceleration forces on the vehicle and hence the risk of injury to the occupants.

By way of contrast the beam-type safety barriers tend to have a higher initial rigidity and tend to be more effective at limiting vehicle incursion, which can be of critical importance where the barrier is used in close proximity to fixed objects such as lighting columns and bridge piers. The open box beam in particular is noted for its high rigidity and would be favoured in situations where vehicle containment was the overriding priority, for example where the roadway crosses over a railway line.

In rather less critical situations a corrugated beam provides a more compliant solution and this system has been employed extensively on British roads. It is known to give a similar deflection on impact to the wire rope safety fence, although it uses more steel and is more costly to erect and maintain, and therefore increasingly difficult to justify in terms of life cycle costing. The corrugated steel beam section is deliberately designed to have a high second moment of area, so that its flexural stiffness is maximised.

The wire rope components of the safety fence on the other hand have negligible flexural stiffness and rely on their tensile strength to restrain the vehicle. As increasing use if made of such fences to exploit their intrinsic safety features and cost effectiveness, there is growing demand for a safe and reliable method of linking the two types of systems. It is important that the method of connection recognises the step change in the stiffness characteristic of the barrier, particularly when moving from a fence to a more rigid beam-type system.

The existing solution is to continue a wire rope safety fence beyond the end of a corrugated beam barrier so that the two overlap for a distance before the wire ropes are anchored off. This guards against the risk of a vehicle being penetrated or overturned by the starting end of the rigid beam, but introduces the risks and expense associated with the rope anchorage.

The present invention provides apparatus for connecting a first safety barrier section including at least one wire rope and a second safety barrier section including at least one beam, the apparatus comprising attachment means for attaching the at least one wire rope to the at least one beam so that tension in the at least one wire rope is transferred to the second safety barrier section, the at least one wire rope and the end portion of the second safety barrier section adjacent the first safety barrier section being constrained to move together sideways but being relatively movable lengthwise.

Preferred features are set forth in the claims.

In particular, the apparatus may utilise a connecting anchorage which allows the tension in the wire rope to be transmitted directly into the beam section of a rigid barrier (e. g. a corrugated beam). The anchorage may comprise for example one or more housings, bolted to the beam and adapted to receive the end termination of a rope. It is preferable for the rope tension to be transferred to the second barrier section over a significant part of its length. This may be facilitated by interweaving the rope with posts supporting the beam or beams.

A contoured nosing preferably guides the rope (and any impacting vehicle) past the end of the beam section. Typically the protective nose section will be chamfered and/or radiussed in plan view, to minimise the risk of damage to the rope and the vehicle in the event of a collision. The nosing may also be designed to control the position of the rope relative to the end of the beam section.

The anchorage will preferably be positioned on the back face of the beam so that it is not exposed to the risk of impact damage in the event of a vehicle collision. The relative proximity of the anchorage to the nosing is a matter of design choice and whilst they could be virtually integral with one another, it is considered safer and more effective to separate them by a distance approximating to a vehicle length (e. g. 5-15 metres). This provides for a high integrity transitional zone in which both rope and beam are operating in concert.

The invention will be described further, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a plan view of a safety barrier, showing part of a first section, the whole of a second section, and part of a third section; Figure 1 A is an enlarged plan view of the transition between the first and second sections; Figure 2 is a side view of the safety barrier shown in Figure 1; Figures 3A and 3B together constitute an enlarged longitudinal section through the safety barrier shown in Figures 1 and 2; Figure 4 is an enlarged plan view of a transition member which couples the second and third sections ; Figure 5 is a side view of the transition member; Figure 6 is an end view of the transition member; Figure 7 is a side view of one length of corrugated beam, forming part of the second section; Figure 7A is an enlarged detail of Figure 7; Figure 8 is a longitudinal section through a transition assembly at the right-hand end of the second section; Figure 9 is a side view of the transition assembly;

Figure 10 is a plan view of the transition assembly; and Figure 11 is an enlarged section taken on line XI-XI in Figure 9.

The safety barrier illustrated extends, for example, between the two carriageways of a motorway and includes successive sections 1 to 3. The first safety barrier section 1 is in the form of a wire rope safety fence similar to that described in GB-A-2 224 528. The second and third sections 2 and 3 are beam-type safety barriers.

The first safety barrier section 1 includes a series of posts 4 at a spacing of 3.2 m. A pair or wire ropes 6 are placed parallel to each other in slots in the tops of the posts 4. A lower pair of wire ropes 7 are woven through the posts 4 so that they cross between the posts. The lower ropes 17 are supported by locating elements 8 on the posts. The right-hand ends (not shown) of the wire ropes 6 and 7 are anchored to the ground.

The second barrier section 2 comprises a pair of corrugated beams 9a, 9b carried by a series of posts 1 la-d between them. The first post 1 la is spaced 3.2 m from the last post 4 of the first section 1. The first three posts 11 la-c are also spaced 3.2 m apart, but the last two posts 11 c and d are spaced only 1.6 m apart. Each beam 9a (9b) comprises four lengths of corrugated beam of standard cross-section connected together, the length of corrugated beam at the right hand end being considerably shorter than the other lengths. The total length of the second barrier section 2 is approximately 10 or 11 m.

The third safety barrier section 3 comprises an open box section beam 12 (which is more rigid than the corrugated beams 9a, 9b) carried by posts 13 (only one of which is shown) with a spacing of 2. 4 m. The second section 2 is coupled to the third section 3 by a transition member 14 which is best seen in Figures 4 to 6. The transition member 14 is a welded steel fabrication with two corrugated parts 16a, 16b, which are bolted to the beams 9a, 9b respectively, and an extension 17, which is bolted to the box beam 12.

Referring to Figures 1,8, 9, and 10, it will be seen that the right-hand end portion of the second barrier section 2 is provided with a transition assembly or buffer 18 comprising the shorter end portions 19a, 19b of the respective corrugated beams 9a, 9b and a curved deflector or nosing 21 having longitudinally extending fixing portions 22a, 22b which are fixed to the respective beam portions 19a, 19b by welded webs. The deflector or nosing 21 also has a generally semi-cylindrical deflecting portion 24 facing the first barrier section 1.

The wire ropes 6,7 are extended beyond the first section 1 into the section 2. It is to be noted that in Figures 3A and B only one upper rope 6 and one lower rope 7 is shown, for the sake of clarity. The upper ropes 6 diverge on leaving the last post 4 and enter respective upper holes 26 in the deflector or nosing 21. The lower ropes 7 cross after leaving the last post 4 and enter respective lower holes 27 in the deflector or nosing 21. The ropes 6 and 7 extend substantially tangentially to the deflecting portion 24. The height of the ropes is gradually changed in the first section 1 as it approaches the second section 2, so that the longitudinal median level of the ropes is approximately matched to the longitudinal median level of the beams. In particular, the upper ropes 6 are at about the level of the upper corrugation, and the lower ropes 7 are at about the level of the lower corrugation. The change in height of the lower ropes 7 may be minimal, while the height of the upper ropes may increase gradually from the normal height of about 570 mm to a height of about 690 mm above the ground.

Inside the transition assembly or buffer 18 the ropes 6,7 pass through gaps 28a defined behind attachments or holders 28 in the form of brackets which are bolted to the beam portions 19a, 19b inside the deflector or nosing 21. The ropes are frictionally engaged by the holders 28 and the beam portions 19a, 19b. In this way, the ropes 6,7 and the end portion of the second safety barrier section 2 adjacent the first section 1 are constrained to move together sideways, for example under the effect of a vehicle colliding with the transition between the first and second sections 1 and 2. During such a collision, the deflector 21 limits the angles through which the ropes 6,7 are bent and helps to prevent or mitigate damage to the ropes.

In the second barrier section 2, both the upper rope 6 and the lower rope 7 are woven through the posts 11 la-d (or, in other words, the ropes pass around opposite sides of selected posts). Attachments or holders 29 (similar to the holders 28) are bolted to the inner sides of the beams 9a, 9b near the transition member 14. Each holder 29 functions as an anchorage which receives an end termination 31 (Figure 7A) on the associated rope 6 or 7. In this way, the tension which is applied to the ropes 6,7 when the safety barrier is assembled is transmitted to the second safety barrier section 2. The holders 28 and 29 permit differential lengthwise movement of the ropes 6 and 7 relative to the beams 9a, 9b, such movement being caused, for example, by thermal expansion or contraction or by deformation of the safety barrier due to impact.

Various modifications may be made within the scope of the invention. For example, the third safety barrier section may comprise two box-section beams. These two beams could be spaced apart and mounted on separate series of posts. In this case, the two beams of the second barrier section could diverge from the end nearer the first section to the end nearer the third section. The first section could have more or fewer than four ropes. If the safety barrier is to be at the roadside, it is possible to omit one of the corrugated beams of the second section. In this case the deflecting portion 24 of the nosing 21 need not extend through 1800.

The deflector or nosing 21 may be provided with grooves (preferably of arcuate cross-section) extending in the deflecting direction, in order to support the ropes in the horizontal plane in the event of vehicle impact and to lessen the risk of damage to them.

The ropes may pass through holes 32 in the holders 28,29, approximately aligned with the holes 26,27.

The safety fence described above can be arranged to ensure that, when a vehicle collides with the first safety barrier section and continues into contact with the second section, the impact forces are substantially dissipated before the vehicle reaches the more rigid third section. The arrangement also helps to prevent the wire ropes from looping significantly behind the second section.

By bolting down the holders 28 onto the ropes (after the ropes have been tensioned), the buffer 18 can be directly coupled to the ropes so that the second section deflects in unison with the ropes. The interweaving of the ropes around the posts of the second section can assist by transmitting a significant amount of the impact force to these posts. This feature, in conjunction with the holders 28,29 and the terminations 31, ensures that the beams 9a, 9b are free of tension over most of their length The above described safety barrier has been tested by colliding a vehicle with the first section of the safety barrier in such a manner that the vehicle continues into contact with the second section. The tests have shown that, while the buffer 18 and the corrugated beams 9a, 9b have been badly damaged, no significant deflection forces have been observed past the transition member 14 and the third section has not been damaged.

Claims

Claims: 1. Apparatus for connecting a first safety barrier section including at least one wire rope and a second safety barrier section including at least one beam, the apparatus comprising attachment means for attaching the at least one wire rope to the at least one beam so that tension in the at least one wire rope is transferred to the second safety barrier section, the at least one wire rope and the end portion of the second safety barrier section adjacent the first safety barrier section being constrained to move together sideways but being relatively movable lengthwise.
2. Apparatus as claimed in claim 1, including a deflector for covering the end of the second safety barrier section facing the first safety barrier section.
3. Apparatus as claimed in claim 2, in which the deflector has a fixing portion adapted to be connected to the second safety barrier section and a deflecting portion which is bent relative to the wire rope.
4. Apparatus as claimed in claim 3, in which the deflecting portion is curved.
5. Apparatus as claimed in any of claims 1 to 4, in which the attachment means comprises at least one holder through which the wire rope passes.
6. Apparatus as claimed in any of claims 1 to 5, in which the attachment means includes at least one anchorage for connecting the at least one wire rope to the second safety barrier section at a location remote from the said end portion.
7. Apparatus as claimed in claim 6, in which the anchorage is adapted to receive an end termination of the wire rope.

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8. A safety barrier comprising: (a) a first section comprising at least one wire rope under tension; (b) a second section comprising at least one beam, the beam having an outer surface facing a vehicle carriageway and an inner surface facing in the opposite direction to the outer surface; and (c) attachment means for attaching the wire rope to the second section so that tension in the wire rope is transferred to the second section, the wire rope and the end portion of the second section adjacent the first section being constrained to move together sideways but being relatively movable lengthwise.
9. A safety barrier as claimed in claim 8, including a deflector mounted on the end of the second section adjacent the first section, the deflector covering the end of the beam and being bent away from the carriageway in the direction from the second section to the first section.
10. A safety barrier as claimed in claim 8 or 9, in which the beam lies between the attachment means and the carriageway
11. A safety barrier as claimed in any of claims 8 to 10, including a third section comprising at least one beam more rigid than that of the second section, the second and third sections being coupled to each other.
12. A safety barrier as claimed in claim 11, in which the third section comprises at least one box-section beam.
13. A safety barrier as claimed in any of claims 8 to 12, in which the second section includes posts, there are at least two wire ropes, which pass around opposite sides of selected posts carrying the at least one beam of the second section.
14. A safety barrier as claimed in any of claims 7 to 13, in which the second section comprises at least one corrugated beam.

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15. A safety barrier comprising: (a) a first section comprising wire ropes under tension ; (b) a second section comprising a pair of beams arranged side by side; (c) a third section comprising at least one beam more rigid than those of the second section; (d) attachment means for attaching the wire ropes to the beams of the second section so that tension in the wire rope is transferred to the beams of the second section, the wire ropes and the end portions of the beams of the second section adjacent the first section being constrained to move together sideways but being relatively movable lengthwise; and (e) at least one transition member coupling the second section to the third section.
16. A safety barrier as claimed in claim 15, in which the attachment means are arranged between the beams of the second section.
17. A safety barrier as claimed in claim 16 or 17, including a deflector mounted on the end of the beams of the second section adjacent the first section, the deflector covering the ends of the beams and decreasing in width towards the first section.
18. Apparatus for connecting a first safety barrier section including at least one wire rope and a second safety barrier section including at least one beam, substantially as described with reference to, and as shown in, Figures 1 to 3 and 7 to 11 of the accompanying drawings.
19. A safety barrier substantially as described with reference to, and as shown in, the accompanying drawings