EP1047843A1

EP1047843A1 - Crash barrier especially for roads and bridges

Info

Publication number: EP1047843A1
Application number: EP99903977A
Authority: EP
Inventors: Jerzy Kryszof Johansson
Original assignee: BCC Baltic Construction Co AB
Current assignee: BCC Baltic Construction Co AB
Priority date: 1998-01-13
Filing date: 1999-01-13
Publication date: 2000-11-02
Also published as: AU2444699A; CA2318058A1; SE511275C2; SE511275C3; AU744717B2; WO1999036630A1; SE9800053D0; SE9800053L; CA2318058C

Abstract

A barrier has posts (10) with at least one metal cable (11, 12) and at least one impact-absorbing rail (16, 33). The metal cable is pretensioned and extends over at least a major part of the length of the barrier and is arranged in cable holders or grooves (13, 14) on the posts. The impact-absorbing rail or rails (16, 33) is/are mounted on the metal cable or cables (11, 12) and is/are mainly supported thereby.

Description

CRASH BARRIER ESPECIALLY FOR ROADS AND BRIDGES

The present invention relates to a railing or barrier, which is intended especially for roads and bridges.

Barriers of the types used for roads and bridges should be highly crash-resistant. Therefore standards for such barriers have been set by the road administrations in different countries. A very common type of barrier in Europe has elements absorbing the impact at the same level as hub caps, i.e. a longitudinal beam positioned on the normal level of the hub caps of the vehicles. Since passenger cars and lorries have different wheel diameters, these elements must have a considerable vertical extent. The most common construction is an impact-absorbing profiled metal sheet of European standard. This pro- filed metal sheet usually has two longitudinal ridges and an intermediate groove. The heads of the mounting bolts are arranged in this groove so as not to immediately touch vehicles sliding along the barrier. This type of barriers functions excellently as impact-absorbing ele- ments but are unfavourable since they block the view. This is a particularly great disadvantage of bridge barriers especially in urban and motorway environment since vehicles approaching a crossing adjacent to the end of the barrier are in many cases difficult to see. Also for aesthetic reasons, a clearer view should be preferred, above all in areas much frequented by tourists. It has therefore been suggested that this impact-absorbing profiled metal sheet should be divided into individual impact-absorbing rods or tubes. Changing to such im- pact-absorbing elements, however, causes an additional problem since the road administrations in different countries require that the surface of the barrier facing the pavement should be smooth and have no extensible mounting elements. As examples of this technique mention can be made of GB-A-1, 209, 191, GB-A-1, 619, 109, GB-A-2, 466, 910, US-A-3,276,750, FR-A-2, 698, 643 and WO 88/00628.

With a view to improving the strength and increasing the crash resistance of road and bridge barriers, it has also been suggested that the individual impact-absorbing rods or tubes should be replaced by steel cables or that steel cables should be inserted in through holes in the individual impact-absorbing rods or tubes. Road fencing having bare steel cables is frequently used along motor- ways, whereas US-A-2, 907, 552 can be mentioned as an example of road fencing and bridge barriers, in which the steel cables are enclosed in longitudinal tubes.

Bare steel cables are approved by the road administrations for road fencing between roadways, but not as bridge barriers. This depends on the fact that the cables often yield outwards when subjected to impact, such that in difficult cases the vehicle can temporarily move almost one metre past the original position of the steel cables in their non-affected state. When the steel cables are fully enclosed in tubes as is the case in the above- mentioned US-A-1, 907, 552, this outward flexing is reduced to a considerable extent or fully eliminated. A further reason why it is preferred to have the cables fully enclosed in a protective tube is that unprotected cables when subjected to impact mill or cut the body of the crashing vehicle open. Precisely this effect of unprotected cables has made many road administrations completely ban the use of unprotected cables on levels above the normal level of hub caps. An unprotected cable at the upper edge of a bridge barrier of normal height could cause severe personal injuries since the cable in that case would be on a level with the windows of passenger cars. To enable the use of steel cables also at levels above the normal level of hub caps, US-A-2, 907, 552 has suggested a road or bridge barrier with specially designed posts having laterally directed U-shaped cable mountings, which besides serve as mountings for the mounting of U-shaped impact-absorbing rods.

The prior-art road fencing with fully enclosed steel cables certainly has great advantages over road fencing with bare steel cables, but also suffers from a considerable drawback. The road fencing is difficult and, thus, expensive to mount since the steel cables must be passed through the tubes and only after that be subjected to tensile prestress. The known road fencing according to US-A-2, 907, 552 is advantageous compared with road fencing with fully enclosed steel cables since the cables can be mounted separately in their cable mountings, before the U-shaped covers or impact-absorbing rods are pushed sideways over the holders and fixed by means of bolts. A problem with the barriers or road fencing according to the last-mentioned US patent specification is, however, that the U-shaped covers or impact-absorbing rods and their fixing bolts must be mounted before the cables are tensioned, at least in connection with fencing through curves, where the fencing is positioned along the side where the cable is located on the concave side of the road fencing. In this prior-art construction, the fixing bolts for the longitudinal U-shaped covers or impact-absorbing rods in fact hold the cables in the cable mountings. Another problem of this known construction is that the holes in the longitudinal U-shaped covers must be bored in a work-shop or, in most, cases, on the occasion of mounting since the distance between the posts is not always exactly accord- ing to the specifications. Since the fixing bolts for the U-shaped covers also serve as fixing means for the steel cables, it is not sufficient to use merely the steel cables as temporary barriers during the building time. It is in fact an imperative labour safety requirement that at least temporary barriers are erected during this time. If a protective barrier according to US-A-2, 907, 552 is subjected to a light crash, which after all is common- est, the steel cable is in most cases intact whereas the U-shaped protective profiled element must be replaced. If the barrier is arcuate along the concave side of a curve, the above problems arise since the fixing bolts serve to hold the steel cable sideways.

A further drawback of this prior-art construction is that the steel cables are subjected to the weather and, which is most serious, also to road salt when the opposite roadway is being cleared of snow. It is true that the steel cable can be protected with a plastic layer, but since the steel cable is not protected against sunlight from all directions, the service life of the plastic protective layer is affected.

Prior-art road fencing and barriers thus suffer from different kinds of drawbacks. An object of the present invention therefore is to provide a new barrier, in which these drawbacks have been obviated or, in any case, reduced to a considerable extent.

A further object of the invention is to provide a new barrier, in which the need of making holes adjacent to post mountings is obviated, such that the need of preparation at the working site is reduced to a minimum.

A further object of the present invention is to provide a barrier, whose impact-absorbing elements con- sist of one or more longitudinal, pretensioned metal cables and in which these cables can be rapidly mounted on the posts of the barrier and be tensioned to serve as temporary protection before the other barrier components are mounted. One more object of the invention is to provide a barrier, which has longitudinal, pretensioned metal cables as principal impact-absorbing elements and in which these metal cables are essentially protected against the effect of sunlight and road salt. Another object of the invention is to provide a barrier, which has pretensioned cables as main impact-absorbing elements and which permits a comparatively simple subsequent mounting of cable covers and impact-absorbing rods.

These and other objects of the invention are achieved if the barrier is designed as defined in the independent claim. The dependent claims define particularly preferred embodiments of this invention.

Summing up, the invention thus lies in a barrier having posts, at least one metal cable and at least one impact-absorbing rail. The cable is pretensioned and ex- tends over at least a major part of the length of the barrier and is arranged in cable holders or grooves on the posts. The impact-absorbing rail or rails is/are mounted directly on the metal cable or cables and is/are mainly supported thereby. A few preferred embodiments of a barrier according to the present invention will now be described in more detail with reference to the accompanying drawings. Fig. 1 is a schematic view of a central barrier, which is formed according to the present invention. Fig. 2 is a perspective view for illustrating the mounting procedure when mounting the central barrier according to Fig. 1. Fig. 3 is a detail view on a larger scale of a hub cap impact-absorber in the barrier according to Fig. 2.

Fig. 4 is a detail view on a larger scale of a profiled cover rod or cover member in the barrier according to Fig. 2. Fig. 5 is a perspective view of an example of a holder element, which is included in the barrier according to the invention. Fig. 6 is a perspective view of an example of a cable clip, which is included in the barrier according to the invention. Fig. 7 is a side view of the clip according to Fig. 6. Fig. 8 is a perspective view of an example of an extension piece, which is included in the barrier according to the invention. Fig. 9 is a second example of a central barrier accord- ing to the present invention.

Fig. 10 is a third example of a central barrier according to the present invention. Fig. 11 is an example of a side barrier according to the present invention. Fig. 1 schematically shows a short portion of a barrier according to the present invention. The barrier comprises a plurality of posts 10, which support cables 11, 12 of metal, usually metal cables. The cables extend through a groove 13 in the upper end of the posts and through hook-shaped cable holders 14 on the sides of the posts. These cables extend along the barrier and are anchored in ground mountings 15 and pretensioned. The technique of pretensioning the cables is the same as that used for known barriers of similar kind, where the cables are completely unprotected.

It is apparent from Fig. 2 that a central barrier according to the invention has a cover member 16, which covers the upper cable 11. On the inside of the cover member, there is an undercut groove 17 with opposing mouth flanges 18, 19. In this undercut groove, a holder element 20 is inserted and attached. As seen in the drawing, the mouth flanges 18, 19 are arranged at different levels. It is also apparent from the drawing that the holder element portion 21, which is intended to be in- serted into the undercut groove, has such a shape that it can be obliquely positioned and inserted under the flange 18. Since the portion 21 is not as wide as the inner parts of the undercut groove, the portion 21 can be moved over the flange 18 so that the opposite end of the por- tion 21 can be inserted under the flange 19. In order to attach the holder element 20, the flange 19 can be upset against the portion 21. In order to enhance the anchorage or to avoid the need of upsetting, a stop screw 22 can be fastened in a threaded through hole in the portion 21. Therefore, when mounting, a firm attachment of the holder elements 20 is achieved on the inside of the cover mem- ber.

The other end of the holder element 20 is Y-shaped to form a cable groove 23. At the aperture end of the groove, there are outwardly directed flanges 24. A clip 25 has corresponding inwardly directed flanges 26 to be able to be mounted on the holder element 20. The clip 25 has a wedge-shaped projection 27, which is directed inwards towards the cable groove 23, when mounting the clip, and which is pressed against the cable 11 and locks the holder element 20 and thus also the cover member 16 in the mounted position. There is no need for further attachment of the cover member, but to avoid pivoting it is advantageous to form the cover member with surface portions, which are located adjacent to or abut against the posts 10 after mounting. For this purpose, the cover member is provided with inwardly projecting support flanges 28.

The flanges 28 can also be used for another purpose, namely for lenghtening rail portions arranged one after the other. The lengthening is carried out by means of profiled extension pieces 29, which are formed to be inserted into the ends of the adjacent profiled rods or rails and engage by press fitting, on the one hand, a projection 30 on the flanges 28 and, on the other, a projection 31 on the mounting flange 19 and a mounting hook 32, respectively.

The central barrier also has hub cap diverter and impact-absorbing rods or rails 33 on both sides. They are designed in essentially the same way as the cover member 16, but they are mounted on the cables 12 on the normal level of hub caps. As is seen, the impact-absorbing rods 33 are formed as about half the cover member 16, the difference being that the undercut groove 17, which is used for the holder element 20, has been placed between the support flange 28 and the mounting hook 32. In this case, the upper edge of the rods 33 will, after mounting, be located adjacent to or abut against the side surface of the posts 10 to rest against the same, if needed, in the same way as the support flanges 28 at the lower edge of the profiled rods 33.

A barrier according to the present invention is very easy to mount. The positioning of the posts 10 as well as the drawing and pretensioning, respectively, of the cables 11, 12 are performed in the same way as in traditional barriers of this type. The novelty resides in the cables being covered afterwards with, respectively, the cover member 16 and the two hub cap impact-absorbing rods or rails 33. The mounting is easy. Except for possibly an upsetting tool, no special tools are needed, if the flanges 19 and the mounting portion 21 are to be upset on the holder elements 20 for anchorage of the same on the inside of the cover member 16 and the impact-absorbing rods 33, respectively. If the stop screws 22 are completely trusted no upsetting tools are, of course, needed.

After the holder elements 20 have been attached, they are placed over the cable 11 and 12, respectively, such that the cables are received by the cable groove 23. Finally, the holder elements and thus also the cover member and the hub cap impact-absorbing rods, respectively, are anchored by the clips 25 being inserted over the outwardly directed flanges 24 on the holder elements. During the insertion of the clips, the wedges 27 will be pressed into the cables 11, 12 such that a firm and permanent anchorage is achieved.

In the case of a crash, it is easy to replace the damaged portions by repeating the above-mentioned process . Fig. 9 shows yet another preferred embodiment of a central barrier according to the present invention. The design of the different parts is substantially the same as in Figs 2-4, except that the parts corresponding to the support flanges 28 have a different design (the details 34 of the cover member 16 and the details 35 of the hub cap impact-absorbing rods or rails 33, respectively) . In this case, the support flanges 34, 35 have a more frail construction. The purpose thereof is to provide a construction, in which the impact-absorbing cables, if possible, are prevented from breaking by having the possibility of sliding out of their grooves 13, 14 in the posts 10 upon a very violent collision. The reason for this is that the cables 11, 12, at the best, should hold upon impact and that only the posts near the location of the collision should need to be replaced.

As seen in Fig. 10, the cable groove 23 can be de- signed to be able to receive more than one cable 11, 12. This can be necessary in cases where particularly strong barriers are required (e.g. when used as bridge barriers) or within portions, where the cables overlap adjacent to the ground mountings 15. Finally, Fig. 11 shows an example of a side barrier, which is designed according to the invention. In this case, the posts 10 do not have any groove 13 in the upper edge, but instead they are provided with upper and lower hook-shaped cable holders 14. A special cover member is not necessarily needed, but the same profiled rod or rail is used both for the hub cap impact-absorber and the cover member. In this case, the same hub cap impact-absorbing rod as in Fig. 10 is used.

Naturally, the invention is not restricted to the embodiments described above and shown in the drawings, as long as the cover member and the hub cap impact-absorbers, respectively, are kept in place mainly with the aid of holder elements, which are mounted on the cables and connected to or formed in one piece with the profiled rod or rods, which is/are used for the cover member and the hub cap impact-absorbers, respectively. If the barrier is formed as a side barrier on a bridge, the embodiment ac- cording to Fig. 10 can advantageously be used, hub cap impact-absorbers being arranged only on the side of the barrier directed towards the bridge. In the various embodiments, rods and cables have been shown on two levels only. It is, however, possible to use cables and rods on more levels, e.g. three or four, in particular if the barrier is used as a side barrier on a bridge or the like.

The inventive principles can be used also for barri- ers where only some of the longitudinal rods are formed according to the invention. Thus a bridge barrier or side barrier, in particular a high one, can use one or more impact-absorbing rods 33 with associated cables 12, whereas the cover member can be made in a traditional manner. The opposite is also possible, for instance in connection with barriers between roadways or central barriers, the hub cap impact-absorbing rods being formed in a traditional manner of profiled metal sheet ("the European profile") and the cover member 16 being formed according to the inventive principles.

Normally, the impact-absorbing profiles 16, 33 are made of metal, in particular aluminium, to permit production by extrusion. It is, however, also possible to use other materials, such as plastic material, especially fibre reinforced plastic material and in particular carbon fibre reinforced plastic material. In principle, use can be made of any material having sufficiently good qualities in terms of structural strength, weather resistance and fastness to light.

Claims

1. A barrier with posts (10), at least one metal cable (11, 12) and at least one impact-absorbing rail

(16, 33), the metal cable being pretensioned and extending over at least a major part of the length of the barrier and being arranged in cable holders or grooves (13, 14) on the posts, c h a r a c t e r i s e d in that the impact-absorbing rail or rails (16, 33) is/are mounted on the metal cable or cables (11, 12) and is/are mainly supported thereby.

2. A barrier according to claim 1, c h a r a c t e r i s e d in that it has holder elements (20) which are clamped on the metal cable or cables (11, 12) and are connected to the impact-absorbing rail or rails (16, 33) .

3. A barrier according to claim 1 or 2, c h a r a c t e r i s e d in that the impact-absorbing rail or rails (16, 33) has/have or is/are provided with support means (28, 34, 35), which are intended to rest against the posts (10) or their cable holders (14).

4. A barrier according to claim 2 or 3, c h a r a c t e r i s e d in that the holders (20) comprise a cable clamp (20) which is attached on a side of the impact-absorbing rail (16, 33) facing the posts (10) and which has a cable-receiving groove (23) , and a clip (25) mountable on the cable clamp (20) for clamping and locking the cable or the cables in the cable-receiving groove.

5. A barrier according to claim 3 or 4, c h a r a c t e r i s e d in that the cable clamp (20) is substantially Y-shaped with outwardly directed mounting flanges (26) for cooperation with the clip (25) .