The invention relates to impact resisting posts and crash barriers constructed using such posts.

There is massive worldwide use of both temporary and permanent crash barriers and bollards to protect buildings, pedestrians and other road users from vehicular impact as well as to prevent vehicles from gaining access to roads and other areas.

Bollards and barriers are often used to provide protection to buildings and other structures likely to be hit by slowly moving vehicles. For example barriers are often placed around lamp posts that are situated in car parks so as to prevent them being damaged by parking vehicles. Conventionally these barriers and bollards are rigid and can be deformed or damaged relatively easily by an impact, especially by impacts from heavier vehicles such as HGVs and forklift trucks. Such bollards and barriers must be replaced after every significant impact. This canbe a substantial expense especially if the bollards or barriers are situated in positions where collisions are fairly regular occurrences, such as lorry loading bays. Additionally the rigidity of the barriers and bollards tends to produce significant damage to the vehicle causing the impact. To reduce this problem some bollards and barriers have soft buffers attached to their impacting surfaces. However this only reduces damage to the colliding vehicle and the impacting surface of the barrier or bollard and does not prevent plastic deformation of the barrier or bollard during most collisions. Therefore the use of rigid barriers and bollards tends to be restricted to situations where the potential cost of damage caused by vehicles colliding with the structure being protected is much greater than the cost likely to be incurred when a vehicle collides with a barrier or bollard.

A solution to these problems is the use of barriers which have supports made of spring steel. Current spring steel barriers are designed to absorb low speed impacts and so lessen damage to the vehicle and barrier. They differ from conventional barriers in that the barrier supports are made of rectangular cross section spring steel formed so as that it is able to flex in the horizontal direction perpendicular to the barrier length. Specifically the barriers are supported by generally vertical lengths of rectangular cross section spring steel that extends downwards

to a securing point. This design means that upon impact the barrier is pushed backwards and rotates towards the floor as the steel flexes at one or more points below the barrier at which the stress is concentrated. Currently the barrier supports are made of thin sections of spring steel and this combined with their design means they will plastically deform at these stress concentration points under all but the lightest of impacts. After each collision in which the barrier support is plastically deformed it will need to be repaired or replaced and this may incur substantial cost or cause significant disruption, ftideed the supports will need to be replaced after a finite number of crashes in which they have been plastically deformed as their structural properties will have been diminished by each such impact.

These barriers are not used for high speed impacts for two reasons; firstly the materials currently used are too weak to be able to withstand impact from a high speed vehicle but secondly and perhaps more importantly the method of deformation is unsuitable for such applications. The fact the barrier will rotate backwards towards the ground about the securing point below the barrier can cause significant problems for an impacting vehicle. The force caused by a vehicle colliding with the barrier at high speed may be enough to cause the barrier to rotate back until it forms a sloping surface relative to the ground. This will either act as a ramp encouraging the colliding vehicle to pass over the barrier or, if the front of the vehicle does not slip over the barrier,. may cause the rear end of the vehicle to rise off the ground which would cause the vehicle to either flip over or crash back down with significant force.

Another major use of crash barriers is on road sidings, motorway central reservations and other positions where barriers are needed to prevent high speed vehicles from colliding with structures and other hazards or coming to rest in hazardous positions, such as on railway tracks. For example on road bridges passing over railways it is usual practice to have a significant length of barrier either side of the bridge to prevent vehicles which leave the road crossing the railway tracks. As stated in the Highways Agency's review of safety fences which was completed in February 2002 "the prime requirements of safety barriers are to prevent vehicles from crossing from one carriageway to the other and to prevent errant vehicles (that is, vehicles leaving the carriageway) from impacting with or entering roadside hazards". Additionally, all such barriers are subject to regulations laid down in the UK safety

barrier standard; "Safety Fences and Barriers" TD 19/85. This standard is based upon existing barrier types which all operate according to the principles laid out in section 3.2 of the standard:

"A safety fence is intended to absorb some of the energy impact caused by an errant vehicle striking it and to redirect the vehicle within a narrow angle to follow the line of the fence so that it does not gyrate or overturn.

A safety barrier is intended to provide containment without significant deflection or deformation under impact, and to redirect errant vehicles along the line of the barrier in the direction of the traffic movement."

There are a number of reasons given for this preferred method of barrier operation. Firstly energy absorption by a barrier, for example by plastic deformation, reduces the severity of the damage caused to the impacting vehicle and thus reduces likelihood of serious injury of the occupants of the vehicle. The prevention of the vehicle overturning is to minimise the possibility of the vehicle's occupants being trapped. Finally the redirection of the impacting vehicle along the line of the barrier, which is commonly called containment, is so that the vehicle does not re_enter the stream of traffic. In practice these regulations mean that only two types of barrier were deemed suitable for use on high speed roads in Britain in 1985.

The first of these barriers consists of longitudinal tensioned steel beams supported by 'Z' section steel posts. The tensioned steel beams are either corrugated beam (CB) or rectangular hollow section beam (RHS). CB has a 'W shape when viewed in cross section and RHS is a simple hollow rectangular beam that is conventionally either 100mm x 100mm or 200mm x 100mm in cross section. When attached to the posts both these types of beams are tensioned along the length of the barrier between anchorage points. When a barrier constructed in this manner experiences an impact the posts plastically deform in the direction perpendicular to the barrier's length whilst the tensioned beam maintains structural integrity along the barrier's length. The plastic deformation of the barrier results in a slower deceleration of the impacting vehicle compared to collision with a rigid barrier and thus reduces the degree of damage to the impacting vehicle and the likelihood of injury to the vehicle's occupants. The

maintenance of the structural integrity of the tensioned beam causes the impacting vehicle to be redirected along the barriers length and prevents the vehicle from overturning or entering roadside hazards, as required by the standard.

The second type of barrier is the British Concrete Barrier (BCB). This is a solid concrete barrier that has a profile contoured to assist vehicle redirection. However the BCB is entirely made of concrete and as such provides very low energy absorption during any impact. Therefore any vehicle impacting with such a barrier at anything Other than a narrow angle or very low speed will not be redirected arid will instead experience significant damage with the possibility of serious injury to its occupants. This means that the use of BCB barriers has been minimised and is limited to sites where only a short length of barrier (less than 45m) can be installed and it is not possible to provide a suitable spacing between anchorage points for a CB or RHS barrier.

Additionally since the publication of the British Standard there has been introduced the use of tensioned wire barriers that are constructed in the same manner as tensioned beam barriers but have tensioned steel wires (TSW) in place of the tensioned steel beams. These operate in exactly the same manner as CB and RHS barriers.

However, in practice the operation of CB, RHS and TSW barriers according to the British standard is not ideal. The redirection of impacting vehicles along their length (containment) causes a prolonged vehicle_barrier contact which may result in parts of the vehicle being torn off and scattered into the path of following vehicles as well as causing permanent damage to the extended length of barrier over which the collision occurs. The debris caused by such an impact often causes secondary accidents when following vehicles either lose control on the debris or swerve to avoid it. Additionally each collision causes permanent damage to a significant length of crash barrier and this entire length of barrier must be replaced. This replacement of crash barriers is a major expense and can also cause significant disruption if the barrier is situated alongside busy highways.

A wide variety of vehicles are present on most roads and roadside crash barriers should be able to cope with an impact from any of them, hi the UK barriers are tested with a 1500kg

saloon car impacting at 70mph from an approach angle of 20° to test for the likelihood of the barrier causing injuries to a lighter vehicle's occupants and with 16 and 30 tonne lorries travelling in a similar manner to test for containment. The fact that validated barriers must pass both of these test means the barriers currently in use are a compromise; they are strong enough to cope with an impact from lighter HGVs and are not likely to cause fatal injuries to the occupants of medium sized family cars travelling at average speeds. However they are unable to cope with impact from very heavy vehicles and they do little to minimise injuries to the occupants of lighter vehicles or those travelling significantly over 70mph. This is a significant problem as many drivers routinely drive over 70mph on motorways and a considerable number of cars being driven in the UK weigh considerably less than the weight for which the motorway barriers are validated. For example a Ford Fiesta weighs approximately 900kg.

According to a first aspect of the invention there is provided an impact resistant post having the features specified in claim 1.

According to a further aspect of the invention there is provided a barrier member having the features recited in claim 22.

According to a further aspect of the invention there is provided a barrier member having the features recited in claim 28.

According to a further aspect of the invention there is provided a crash-barrier having the features recited in claim 33.

According to a further aspect of the invention there is provided a crash-barrier having the features recited in claim 46.

According to a further aspect of the invention there is provided a impact resisting gate having the features recited in claim 47.

According to a preferred aspect of the present invention there is provided an impact resisting

post comprising a length of generally rectangular cross section spring steel having mutually relatively wider and narrower faces that includes: an anchorage portion; an upright portion which extends upwardly from said anchorage portion; a bent portion in a plane perpendicular to the wider faces of said upright portion, having a proximal end integral with an upper end of said upright portion and a distal end integral with a downward portion of the post; the downward portion being spaced from the upward portion to avoid contact therewith, and terrrώiating at a height above the junction between the anchorage portion and the upright portion; wherein: when said post experiences an impact that exerts a horizontal force on said downward portion in the direction of the upright portion, said upright portion moves resiliently away from the impact in a direction perpendicular to the wider faces of the upright portion; and said downward portion moves resiliently towards said upright portion with flexure of the bent portion.

Preferably said anchorage portion is fixed in the ground by receiving the anchorage portion in a sleeve or bracket.

Preferably said anchorage portion is fixed in the ground by setting said anchorage portion or said sleeve in concrete such that the upright portion protrudes upward from the concrete's upper surface.

Preferably the anchorage portion is vertical and is contained within a bracket also set within the concrete.

Preferably said post is additionally secured in the concrete by means of a wedge forced between the spring steel and the concrete at the concrete's upper surface.

Preferably said anchorage portion is substantially horizontal, generally parallel to amounting surface and is fixed by said fixing means to said surface.

Preferably said fixing means is a bracket attached to the mounting surface such that said anchorage portion may be accepted into said bracket.

Preferably said anchorage portion may be additionally fixed in said bracket by a securing means.

Preferably said post additionally comprises a second bent portion at the lower end of said downward portion which substantially forms an eye at said lower end of said downward portion wherein a barrier may be formed from a plurality of said posts by joining said plurality said posts by barrier members which pass through said eyes.

Preferably a cushioning material is attached to the outer face of the downward portion over the length of said portion at which impact is likely to occur.

Preferably said cushioning material is substantially a block of rubber which is fixed to the outer face of the downward portion over the length of said portion at which impacts are likely to occur.

According to another preferred aspect of the invention there is provided a crash barrier comprising a barrier member attached between adjacent ones of said plurality of posts.

According to another preferred aspect of the invention there is provided a crash barrier comprising a barrier member attached between adjacent ones of said plurality of posts, wherein said barrier members are attached to the outer faces of the downward portion of said posts.

Preferably said barrier members are lengths of conventional motorway CB.

Preferably said barrier members are lengths of conventional motorway RHS.

Preferably each post additionally comprises a second upward portion joined to the lower end of the downward portion by a second bent portion such that it is parallel to and of a similar length to the downward portion with a slot formed between the downward portion and the second upright portion; and wherein said barrier members are attached to said posts by slotting a sleeve member attached to each barrier member into said slot.

Preferably said barrier members are lengths of conventional motorway CB with said sleeve members attached to their inner face.

Preferably said barrier members are lengths of conventional motorway RHS with said sleeve members attached to their inner face.

Preferably each barrier member is additionally secured in said slot by locking means which pass through the second upright portion of said post to prevent the barrier member from being lifted out of said slot.

Preferably each barrier member is additionally secured in said slot by locking means which pass through the downward portion of said post to prevent the barrier member from being lifted out of said slot.

Preferably each barrier member is additionally secured in said slot by locking means which passes through the downward portion and the second upright portion of said post to prevent the barrier member from being lifted out of said slot.

Preferably each barrier member is additionally secured in said slot by locking means which passes though and may be fixed in said slot in a direction parallel to the barrier member to prevent the barrier member from being lifted out of said slot.

Preferably a reinforcing post is sited behind each of said impact resisting posts in such a position that the upright portion of each of said impact resisting posts is spaced from the reinforcing post sited behind it and will not contact said reinforcing post when subjected to relatively light impacts but will contact said reinforcing post when subjected to relatively heavy impacts.

Preferably each of said reinforcing posts is an impact resisting post according to any of claims 1 to 11 and is sited behind each of the other impact resisting posts such that the outer face of their downward portions are facing, aligned with and spaced from the upright portion of each of said other impact resisting posts.

Preferably each of said reinforcing posts is comprises a length of generally rectangular cross section spring steel having mutually relatively wider and narrower faces that includes an anchorage portion and an upright portion which extends upwardly from said anchorage portion and is of a similar height to the upright portion of said impact resisting posts; and wherein each reinforcing post is sited behind each impacting resisting post such that the upper end of the upright portion of each of said reinforcing posts is facing, aligned with and spaced from the upper end of the upright portion of each of said impact resisting posts.

Preferably said anchorage portion of said reinforcing post is fixed in the ground by setting said anchorage portion of the length of spring steel in concrete such that the upright portion protrudes upward from the concrete's upper surface.

Preferably said anchorage portion of said reinforcing post is vertical and is contained within a bracket also set within the concrete.

Preferably said anchorage portion of said reinforcing post is additionally secured in the concrete by means of a wedge forced between the spring steel and the concrete at the concrete's upper surface.

Preferably said anchorage portion of said reinforcing post is substantially horizontal, generally parallel to a mounting surface and is fixed by said fixing means to said surface.

Preferably said fixing means is a bracket attached to the mounting surface such that said anchorage portion may be accepted into said bracket.

Preferably said anchorage portion of said reinforcing post maybe additionally fixed in said bracket by a securing means.

Preferably said reinforcing post is sited such that the wider face of said anchorage portion of said reinforcing portion is in full contact with the wider face of the anchorage portion of the impact resisting post behind which said reinforcing post is sited and both of said anchorage portions are fixed in the same manner.

Preferably said upright portion of each of said reinforcing posts is slightly curved such that the upper end of said upright portion is substantially vertical and parallel to the upper portion of the impact resisting post behind from which it is spaced and the lower end of said upright portion of each of said reinforcing posts is parallel to and sloped away from the lower end of the upright portion of the impact resisting post from which it is spaced.

The posts are designed to be placed in situations where it is desirable to prevent vehicles colliding with structures or other vehicles and are suitable for both preventing head_on low speed collisions, for example in front of HGV loading bays, and when used as part of crash barriers for deflecting high speed collisions, for example on motorway central reservations. It is also possible to build crash barriers using the posts in situations where low speed collisions are expected such as in car parks. In all these situations the posts are designed to be positioned such that collisions will compress the downward portion of the post towards the upright portion in the horizontal direction.

The posts are designed to elastically deform upon impact so that a colliding vehicle suffers a lower deceleration than that which would occur if the vehicle hit a rigid structure and thereby lessen the probability of injuries to the vehicle's occupants and lessen the damage caused to the vehicle itself. Upon collision the post will elastically deform in a manner such that the upright portion bends backwards and the downward portion bends inwards. The stress caused by an impact will be highest in the bent portion and at the intersection between the upright and anchorage portions. The deformation will cause the point of impact to move elastically backwards, away from the point of collision, such that the vehicle is brought to a halt over a longer distance than in a collision with a rigid barrier. Additionally the design of the post means that during a collision the impacting portion of the post will move approximately horizontally backwards and there will not be any problems caused by the post or barrier becoming slanted and acting as a ramp during a collision. After the vehicle has been halted the post will elastically rebound towards its initial position pushing the vehicle away from the post or barrier. Preferably the grade and dimensions of the steel used will be such that the post will not suffer any plastic deformation in the collisions it is designed to withstand and it will therefore return to its initial position when the colliding vehicle is removed. When used individually as bollards to protect against low speed head_on collisions it is preferable to

provide a soft or easily deformable material on the outer face of the post at the point at which impact is likely to occur in order to minimise any damage occurring to the impacting portion of the colliding vehicle The posts may be secured in a variety of manners as long as both the upright and downward portions have enough space to flex away from an impact. For example they maybe secured by penetrating the post into the ground and setting the anchorage portion of the post in concrete or, if the post is formed such that the anchorage portion is horizontal, by bolting or otherwise fixing said anchorage portion to the ground.

Alternatively by providing a suitable anchorage portion such that said portion may be secured to, and project out from, a vertical surface the posts may be attached to such surfaces, for example loading bay walls.

By using the posts as the supporting members for a conventional barrier member, barriers may easily be formed. The posts may be formed so as to more easily support the barrier member. For example a loop may be provided at the lower end of the post's downward portion such that a length of wire or a rigid bar may be passed through the loops of more than one suitably sited post to form a length of barrier. Preferably when used as barrier member supports the posts should be oriented such that the outward face of each downward portion is perpendicular to the barrier length at that point. This will produce a barrier in which each supporting post will react to a collision in much the same way as described above for an individual post. Preferably the barrier members supported by the post are easily attached and removed from the posts so that after a collision if the barrier members experience significant plastic deformation and/or fail they may be easily replaced without the need to replace the posts, which are unlikely to fail and/or plastically deform. These barriers may be used alongside lower speed roads for protecting against low speed impacts, for example in a car park.

By pairing the impact resisting posts with stronger reinforcing posts, barriers suitable for motorway use may be formed. Preferably the reinforcing posts will be spring steel posts that are designed to withstand impacts from HGVs weighing in excess of 30 tonnes. Preferably impact resisting posts paired with each reinforcing post will be designed to withstand impacts from smaller vehicles such as cars, which may range in weight from 900 to 3,000 kg. The

reinforcing posts may be formed in the same manner as the impact resisting posts or may be simple substantially straight lengths of rectangular cross section spring steel. In use the reinforcing posts are placed directly behind, parallel to and slightly separated from each impact resisting post. This combination of the posts can be used in such a manner that they directly replace the 'Z' section steel posts currently in use for tensioned steel barriers. This may done by fixing a number of the combination posts at regular intervals along the length intended to be protected by the barrier such that all the impact resisting posts are in the same orientation with the outer faces of the downward portions of the impact resisting posts perpendicular to the length of the intended barrier and facing the direction of potential impact, and then by fixing lengths of conventional crash barrier CB or RHS to the outer face of each of said posts such that they are vertical, at such a height and in such an orientation that their outer faces will be hit by the expected impact and so that a continuous barrier is formed in front of and between the posts by the lengths of CB or RHS. If needed the lengths of CB or RHS may be tensioned and anchored at each end of the barrier to provide greater longitudinal structural integrity.

Barriers formed in this way could also be used on road sidings near railways to prevent vehicle_train collisions. If a double sided barrier is necessary, such as in a motorway central reservation, this can be achieved by placing two single sided barriers back to back with a gap between them sufficient to allow the posts to flex backwards during a vehicle_barrier collision. This gap could be minimised by staggering the two barriers such that the posts of each barrier are not coincident. When a motorway crash barrier constructed using these posts experiences an impact the CB or RHS will maintain their structural integrity along the longitudinal length of the barrier and as a result the force experienced by each pair of posts will be approximately perpendicular to the length of the barrier. In this way during a collision each impact resisting post will act in the same manner as described above for a low speed collision. If the impacting vehicle collides with a force that the impact resisting post has been designed to withstand then it will act elastically in exactly the same manner as if the reinforcing post had not been present. However, if the impacting vehicle collides with more force than the impact resisting post has been designed to withstand, for example if the vehicle is an HGV or is a speeding car, the impact resisting post will elastically deform far enough so that the back face of its upright portion impacts upon the face of the reinforcing post. As each

reinforcing post is substantially stiffer than its partner impact resisting post the reinforcing post will then prevent further significant deformation of the upright portion of the impact resisting post whilst, to a lesser degree, deforming away from the collision and absorbing the energy of the impact itself. The only part of the either post that may plastically deform during such a collision will be the bent portion of the impact resisting post. In this manner the posts may protect against a wide range of impacts, from light cars to very heavy goods vehicles without significant plastic deformation or the possibility of failure.

As barriers constructed in this maintain their structural integrity during a collision and the posts will in most cases elastically deform, the impacting vehicle or vehicles will, depending on the speed and direction of impact, tend to rebound off the barrier. In high speed situations this will reduce the length of tensioned beam that is damaged by each impact as compared to conventional motorway barriers. However, much more importantly it will reduce the amount of debris that flies off the vehicle and so reduce the possibility of secondary accidents caused when cars suddenly brake to avoid such debris or lose control as they drive over or hit it. With suitable engineering the rebound strength of the barriers may be designed such that when a collision is caused by a car gently swerving into the barrier from the adjacent road lane, for example when a driver falls asleep at the wheel, it will rebound no further than said adjacent lane, thereby allowing following vehicles to pass the collision in any other available lanes.

The invention will now be described, byway of example only, with reference to the attached figures in which:

Figure 1 shows a side view of an embodiment of a single post with an anchorage portion which may be secured vertically in the ground;

Figure 2 shows a three dimensional view of the same post secured in the ground using a bracket and with a rubber buffer attached to the outer face of the downward portion;

Figure 3 shows a side view of an embodiment of a single post with an anchorage portion which may be horizontally secured to the ground;

Figure 4 shows a three dimensional view of the same post secured to the ground using a bracket and with a rubber buffer attached to the outer face of the downward portion;

Figure 5 shows a side view of an embodiment of a single post with a second upright portion to enable it to be easily attached to a suitable barrier member;

Figure 6 shows a three dimensional view of a short length of crash barrier constructed using the same posts attached to a length of CB;

Figure 7 shows a side view of an embodiment of a single post with an eye at the lower end of the downward portion;

Figure 8 shows a three dimensional view of a short length of barrier constructed using the same posts;

Figure 9 shows a three dimensional view of an impact resisting post and reinforcing post as may be used in motorway crash barriers;

Figures 10(a) shows a plan view of a barrier member of a first type;

Figures 10(b) shows a plan view of a barrier member of a second type;

Figures 10(c) shows a side view of the barrier member of the first type;

Figures 10(d) shows a side view of the barrier member of the second type;

Figure 10(e) shows an extended length of crash barrier section assembled from barrier members of the first and second type;

Figure 11 shows a simplified perspective view of a crash barrier assembled from a plurality of barrier members and a plurality of impact resisting posts;

Figure 12 shows a perspective view of a portion of a crash barrier assembled from a plurality

of barrier members and the impact resisting and reinforcing posts;

Figure 13 shows a perspective view of a portion of a crash barrier assembled from a plurality of barrier members and conventional posts;

Figure 14(a) shows a side view of a further embodiment of a single post;

Figure 14(b) shows a side view of an embodiment of a parallel barrier mounting post;

Figure 14(c) shows a side view of a further embodiment of a parallel barrier mounting post;

Figure 14(d) shows a side view of an embodiment of a long drop mounting post;

Figure 15 (a) shows a side view of an embodiment of a double hooked post;

Figure 15(b) shows a side view of a further embodiment of a a double hooked post;

Figure 16 shows a simplified perspective view of a first embodiment of a crash barrier gate; and

Figure 17 shows a simplified perspective view of a second embodiment of a crash barrier gate;

A number of embodiments of the invention will be described referring to the attached drawings.

A first preferred embodiment of the present invention is shown in figure 1. This embodiment consists of a single piece of rectangular cross section spring steel that has been formed into a hook shape such that it consists of an anchorage portion 7, an upright portion 2, a bent portion 3 and a downward portion 4, wherein both the upright portion 2 and the downward portion 4 are straight.

This embodiment of the invention may be fixed in the ground as shown in figure 2. The

anchorage portion 7 is set vertically in the ground to a significant depth such that the post 1 is securely fixed, the lower end of the downward portion 4 does not contact the ground and the outer face of said downward portion 4 is facing the direction of probable impact. The post 1 may be set in the ground using a receiving bracket or sleeve 5 that is fixed in the ground, for example by setting in concrete, before the post so that it is vertical and may accept the anchorage portion 7 of the post 1. The post 1 may then slotted into the bracket 5 such that it is vertical and facing the direction of probable impact. Additionally a rubber buffer 6 may be attached to the outer face of the downward portion 4 to provide a softer impacting surface that is less likely to damage a vehicle during a collision. During a collision this embodiment of the invention will experience the greatest stress in its bent portion 3 and at the intersection between the anchorage portion 7 and the upright portion 2, said intersection being the point at which the post 1 enters the ground.

Conveniently, the anchorage portion may be received in the bracket / sleeve such that the anchorage portion may move a certain amount, within the bracket, on impact. This reduces the stress exerted on the intersection between the anchorage portion 7 and the upright portion

2.

A second preferred embodiment of the invention is shown in figure 3. This post 8 is also is made from a single piece of rectangular cross section spring steel that has been formed into the shape shown. In the same manner as the previous embodiment this post 8 has an upright portion 9, a bent portion 10 and a downward portion 11 that together substantially form a hook shape. At the lower end of the upright portion 9 the anchorage portion 12 extends backwards from the upright portion 8 such that the two portions are approximately perpendicular.

This embodiment is designed for situations where it is impossible to set the post 8 in the ground to a significant depth, for example where there is an existing concrete surface that can not be dug up in order to set a bracket and/or it is not possible to dig a hole deep enough to accommodate a significant length of the post. One method of fixing this post 8 is shown in figure 4. A suitable bracket or sleeve 13 is fixed to the ground using a number of bolts 14. The bracket 13 is formed such that the anchorage portion 12 of the post 8 maybe slid in and out

of it as necessary and so that the upright portion 9 is substantially vertical. Additionally a rubber buffer 15 may be attached to the outer face of the downward portion 11 to provide a softer impacting surface that is less likely to damage a vehicle during a collision. During a collision this embodiment of the invention will experience the greatest stress in its bent portion 10 and at the intersection 16 between the upright portion 9 and the anchorage portion 12. There may also be fixing means (not shown) for fixing the post 8 in the bracket 13 such as a bolt passing through the anchorage portion 12 of the post 8 and the bracket 13. An alternative method of fixing this embodiment of the invention to the ground would be to simply bolt or pin the length of the anchorage portion 12 directly to the ground.

In order to make the above embodiment more secure against impact a facing portion (not shown) may be used. Such a facing portion would be formed from a straight length of rectangular cross section steel, of a similar width to that from which the post 8 is constructed, and set substantially vertically in the ground behind the anchorage portion 12 such that a part of the facing portion is above the ground, and said part has its wider face parallel and immediately adjacent to the end of the anchorage portion 12 furthest from the upright portion 9. In this arrangement when the outer face of the downward portion 11 experiences an impact the post 8 is pushed backwards in the bracket 13 and the far end of the anchorage portion 12 comes into contact with the length of the facing portion that is above the ground, preventing the intersection 16 between the upright portion 9 and the anchorage portion 12 being forced back into the bracket 13. This is desirable because forcing the intersection 16 into the bracket 13 could, if the post 8 is impacted with sufficient force, cause the bracket 13 to be pulled away from the surface to which it is attached.

As described previously, the anchorage portion maybe received in the bracket / sleeve such that the anchorage portion may move a certain amount, within the bracket, on impact.

A third preferred embodiment of the invention to be used to create lengths of barriers is shown in figure 5. This embodiment 17 consists of a single length of rectangular cross section spring steel that has been formed in to the shape shown. The post 17 has an anchorage portion 35 , an extended upright portion 18, a bent portion 19 and a downward portion 20 in the same manner as the first preferred embodiment. However this embodiment also has a second

upward portion 22 that is joined to the lower end of the downward portion 20 by a second bent portion 21 such that it is parallel to and of a similar length to the downward portion 20. A slot 23 is formed between the downward portion 20 and the second upright portion 22. This post 17 may be fixed in the ground in exactly the same manner as the first embodiment. An alternative of this embodiment would have an anchorage portion perpendicular to, and at the lower end of, the upright portion 18 in much the same manner as the second preferred embodiment of the invention as described above. This alternative embodiment could be fixed in position using the fixing methods described for the second preferred embodiment of the invention.

The use of the third preferred embodiment of the invention to make a length of crash barrier 25 is shown in figure 6. The figure shows a short length of barrier 25 in which a length of conventional motorway CB 24 has been attached to the outer faces of two posts 17 such that it is at the height of likely impact and forms a continuous barrier between the posts. The posts 17 are securely fixed in the ground in the manner described for the first preferred embodiment. The CB 24 is attached to each post 17 by means of sleeve members 26 attached to the inner side of the CB 24 such that they may be slid into the slot 23 formed in each post 17 by simply lowering the CB 24 onto the posts 17. This secures the CB 24 against all horizontal impacts and also enables the CB 24 to be easily replaced should it be damaged during a collision. For additional security there may be a locking mechanism (not shown) on each post 17 situated above the upper sleeve member 26 such that an CB 24 could not be either installed or removed without first unlocking said mechanism.

It will be readily understood from figure 6 that a much longer length of barrier could be formed in the following manner. A suitable number of posts may be fixed in position such that they are suitably spaced along the length to be protected by the barrier and in an orientation such that their outer faces are perpendicular to the length of the barrier and facing the direction of likely impact. Lengths of CB may then be fixed between each pair of posts in the manner described above so as to form a number of the short barriers shown in figure 6. Each end of these short barriers may then be joined to the immediately adjacent short barrier by additional CB lengths in such a manner that each of said additional CB lengths is fixed at each end to the end of an CB which previously formed one of said short barriers and a

continuous length of CB is formed along the length of the desired barrier. Preferably said additional CB lengths will be fixed by means that is secure but readily undone, such as a nut and bolt, so that any given length of CB maybe unattached and replaced if it is damaged in a collision. Barriers constructed in this manner would be suitable for protecting against lower speed vehicular impacts, such as alongside 30 mph limited roads or in car parks.

As shown in Figure 9 the third preferred embodiment of the impact resisting post 17 may also be used to construct crash barriers suitable for protecting against high speed impacts from a wide range of vehicles. This is achieved by pairing each impact resisting post 17 with a rectangular cross section spring steel reinforcing post 35 that is substantially stiffer than its partner impact resisting post 17. The embodiment of the reinforcing post shown in Figure 9 consists of a anchorage portion (not shown) and an upright portion 36. The reinforcing post 35 is fixed in position, by its anchorage portion and by any of the methods described for the impact resisting post 17, such that its upright portion 36 is slightly behind the upright portion of the impact resisting post 18. The upright portion 36 of the reinforcing post is slightly curved such that it is closest to the upright portion of the impact resisting post 18 at its lower end and is of such a length that its upper end is at substantially the same height as the upper end of the upright portion of the impact resisting post 18. There may also be a cushioning buffer 37 attached at the upper end of the upright portion 36 of the reinforcing post to protect both posts against damage caused when the upright portion of the impact resisting post 18 is forced towards the upright portion 36 of the reinforcing post during a collision. A barrier may be formed from these pairs of posts by attaching conventional motorway CBs between impact resisting posts 17 in the same manner as described above for a barrier suitable for protecting against low speed vehicular impacts.

By suitably engineering the elastic strength of the reinforcing posts 35, and impact resisting posts 17 a barrier suitable for motorway use may be constructed. Preferably the impact resisting posts 17 will be engineered such that they may elastically resist impacts from light to moderately heavy vehicles travelling at speeds up to 70 mph without contacting the reinforcing post 35. Preferably the reinforcing post 35 will be significantly more resilient than the impact resisting post 17 such that if the barrier experiences an exceptional impact, such as from a very heavy goods vehicle, and the impact resisting post 17 is forced into contact with

the reinforcing post 35 the reinforcing post 35 will prevent further significant deformation of the impact resisting post 17 and elastically absorb the energy of the impact itself without significantly any significant plastic deformation.

A fourth preferred embodiment of the invention is shown in Figure 7. This post 27 is also is made from a single piece of rectangular cross section spring steel that has been formed into the shape shown. In the same manner as the previous embodiments this post 27 has an upright portion 28, a bent portion 29 and a downward portion that together substantially form a hook shape as well as an anchorage portion 36. Additionally at the lower end of the downward portion there is a second bent portion 31 that forms an eye 32. This embodiment may be fixed in the ground in the same manner as the first preferred embodiment. It will also be understood that an alternative of this embodiment would have an anchorage portion which is perpendicular to, and at the lower end ol the upright portion 27 in much the same manner as the second embodiment of. the invention as described above. This alternative embodiment could be fixed in position using the fixing methods described for the second preferred embodiment of the invention. The use of the fourth preferred embodiment is shown in figure 8. The posts 27 are fixed in position such that the outer faces of their downward portions 30 are facing the direction of likely impact and have rubber buffers 33 attached to them to cushion each post 27 and colliding vehicle during a collision. Additionally a barrier member 34 is situated between the posts 27 such that it passes through the eye 32 of each post 27 thereby forming a short barrier. The barrier member 34 may, for example, be a steel bar. Additionally there may be a fixing member (not shown) at each end of the barrier member 34 such that the barrier member 34 may not be installed or removed without first unlocking and/or removing the fixing member. A longer length of barrier may easily be formed by suitably positioning a number of posts 27 and situating a barrier member 34 through the eye 32 of each post 27 so as to form a continuous length of barrier. If the barrier is curved a length of chain or steel cable may be used as said barrier member 34.

Figures 10(a) to 10(e) show complementary barrier members of a first and second type at 50a and 50b respectively. Each barrier member 50a, 50b, comprises an elongate section of barrier material 52a, 52b, teraiinated at each end by a hinge portion 54a, 54b. Each barrier member 52a, 52b, is provided with a plurality of mounting portions 56a, 56b, for allowing the barrier

members to be mounted on impact resisting posts as generally described previously.

The barrier material may be any suitable material, but typically will be in the form of rectangular cross-section steel.

Each hinge portions 54a, 54b, is formed from at least one section of barrier material, rolled to form a hinge eye 58a, 58b having an axis extending, substantially perpendicular to the length of the barrier member, in the 'Z' direction. As seen in figures 10(c) and 10 (d) the hinge portion 54a of the first type of barrier member 50a comprises two coaxial hinge eyes 58a extending longitudinally from the top and bottom of the barrier member 50a. Similarly, the hinge portion 54b of the second type of barrier member 50b comprises a single hinge eye 58b extending longitudinally from the centre of the barrier member 50b. The positions and dimensions of the eyes 58a, 58b, of each member 50a, 50b, are configured for coaxial mutual engagement with corresponding eyes of the other member 50a, 50b.

Thus, the hinge portions 54a, 54b, of the respective complementary sections 52a, 52b, are mutually engageable with one another,- and with a locking or hinge pin 60, to form a hinge 62 having a hinge axis extending, substantially perpendicular to the length of the barrier member, in the 'Z' direction, as best seen in figure 10(e). Thus, in operation, a plurality of barrier members 50a, 50b, of alternating type, maybe arranged to form an extended length of crash barrier section, hinged at regular intervals.

It will be appreciated that although two types of barrier member are described, a single type of barrier member could be used in which the hinge portions at opposing ends are mutually engageable to form the hinge. Such barrier members are shown, in operation, in figure 11.

Referring back to figures 10(a) to 10(e), the mounting portions 56a, 56b are located on an inner side of the barrier member at suitable positions along its length, in dependence on the length of the barrier member 50a, 50b, and the required number of posts per unit length. Li the illustration two mounting portions are shown, however, it will be appreciated that any suitable number may be used.

Each mounting portion 54a, 54b comprises at least one sleeve member, configured for mutual engagement with the second upward portion 22 of an impact resisting post of the type described with reference to figures 6 and 9.

In figure 11 a crash barrier is shown generally at 70. The crash barrier 70 is assembled from two extended lengths of barrier section 72, 72', mounted on a plurality of inverted 'J' shaped impact resisting posts 73 as generally described previously.

The extended barrier sections 72, 72' are assembled from barrier members 74, similar to those described with reference to figures 10(a) to 10(d). Unlike the sections of figures 10(a) to 10(d), however, the sections 74 are of a single type having hinge portions 76, at opposing ends of each section. Like the barrier members 50a, 50b, the barrier members 74 are each provided with mounting portions 78 by which the extended sections 72, 72' are mounted on the impact resisting posts 73.

The two extended sections 72, 72' are mounted one above the other in a generally vertical, spaced apart relationship, thereby forming an upper 72 and lower section 72' separated by a gap. The vertical spacing between the extended sections 72, 72' is maintained by a plurality of generally cylindrical tubular spacers 82, each located in between, and in coaxial alignment with the hinge portions 76, 76', of the respective sections 72, 72'. A locking or hinge pin 84 is received through each respective upper hinge portion 76, spacer 82, and lower hinge portion 76' to form a hinged connection between respective barrier members 74, thereby forming a hinged crash-barrier, having two barrier rails 72, 72'.

It will be appreciated that the crash barrier may have any suitable numbers of rails made of an appropriate number of barrier sections, including a single rail.

Figure 12 shows a further implementation of a hinged crash-barrier generally at 90. The barrier 90 is similar to that described with reference to figure 11 and like parts are given like reference numerals. A single section of the crash-barrier is shown for illustrative clarity. It will be appreciated, however, that a plurality of such sections maybe lunged to one another to form an extended length of hinged crash-barrier as generally described previously.

The crash barrier is shown mounted on a plurality of impact resisting posts 92 located at an ^" appropriate distance from one another, each having an associated reinforcing post 93. The posts 92, 93 are similar to those described with reference to figures 6 and 9 and will not be described again in detail. To allow mounting the crash barrier 90 is provided with a plurality of mounting portions 78, each comprising a sleeve member, configured for mutual engagement with a corresponding upward portion 94 of the impact resisting posts 92.

Hence, in typical operation to assemble the barrier, the sleeve members 78 of a barrier member for a lower section 72', of the barrier 90, are received on the upward portions 94 of the impact resisting posts 92. The sleeve members 78 of a barrier member for an upper section 72, of the barrier 90, are then received on the upward portions 94 in a vertical spaced apart relationship with the lower section 72' . A gap is provided between the upper and lower barrier members by cylindrical tubular spacers 82, each located in between, and in coaxial alignment with hinge portions 76, 76', of the members.

Retention means comprising a locking bolt 96 or the like are located above the upper barrier member for the retention of the barrier sections, for example during an impact with the barrier. Locking or hinge pins (not shown) are received through each respective upper hinge portion 76, spacer 82, and lower hinge portion 76' to form a hinged connection between adjacent barrier members of the barrier sections 72, 72', thereby forming a hinged crash- barrier, having two barrier rails 72, 72 ' . A height pin (not shown) or other support means may also be provided for each post, below the barrier sections 72, 72', on which the lower barrier members of each extended section 72' rest during operation.

The locking bolts 96 and height pins (where provided) are located such that, in operation, when the barrier suffers an impact, the sleeve members 78 of the affected barrier members are free to slide, within limits, up and down on the corresponding upward portions 94, thereby giving additional flexibility.

Thus, in operation, when a vehicle strikes the crash barrier 70 the posts 73, 92 flex, as generally described previously, substantially in the 'YZ' plane. At the same time, the extended crash barrier flexes about the hinges, substantially in the 'XY' plane. Furthermore,

the affected barrier members slide on the upward portion providing additional flexibility in the 'ZX' plane. This three-dimensional flexibility is particularly advantageous because it reduces the probability of significant damage to the barrier members, and improves the safety quality of the barrier.

Specifically, where only one-dimensional flexibility is provided, for example using the flexible impact resisting posts without a hinged barrier, damage to the barrier members can prevent the flexible impact resisting posts from returning elastically to their original configuration. The two-dimensional flexibility of the crash-barrier 70, helps prevent damage to the barrier members 74, thereby improving the safety quality of the barrier.

Figure 13 shows a further implementation of a hinged crash-barrier generally at 100. The barrier is similar to those described with reference to figures 11 & 12 and like parts are given like reference numerals.

The barrier 100 is assembled essentially as described for the barrier shown in figure 12 and hence will it not be described again in detail. Unlike those described previously, however, the crash barrier is shown mounted on a plurality of conventional posts 102 located at an appropriate distance from one another. To allow mounting the crash barrier 100 is provided with a plurality of mounting portions 78, each configured for mounting using locking nuts and bolts in a conventional manner.

Even when a hinged barrier is implemented using conventional posts it provides a distinct advantages in terms of damage reduction and improved safety quality.

Figures 14(a) to 14(c) show alternative embodiments of impact resisting posts similar to those described with reference to figures 5 and 6 in particular. The posts 200, 220, 240 will not be described again in detail other than to highlight the principal differences.

As seen in figure 14(a) the post 200 comprises an anchorage portion 202, an upright portion 204, a bent portion 206, a downward portion 208 and a second upward portion 210 as generally described previously. As with the earlier embodiment, a slot 212 is formedbetween

the downward portion 208 and the second upward portion 210. However, the downward and second upward portions 208, 210 and hence the slot 212 are longer than the equivalent features described with reference to figure 5. The lengths are such that the slot 212 reaches almost reaches to ground level, in operation, when the post is installed. Typically, for example, the operational clearance between the portions 208, 210 and the ground is of the order of 100mm.

Posts such as these are particularly advantageous for crash barriers having multiple barrier rails and especially those having three or more such vertically spaced rails formed from associated barrier members. Crash barriers made with such posts have the advantage that the front of a vehicle impacting the barrier will not tend to force itself under the barrier, thereby tending to push the affected barrier members upwardly over the bonnet of the vehicle or the like.

It will be appreciated that where the barriers are bolted directly to the post, the post need not have the second upward portion as shown in figure 14(d). Instead, the barrier members may be bolted to the downward portion directly.

Figures 14(b) and (c) show posts suitable for the parallel mounting of crash barriers.

The parallel mounting post 220 in figure 14(b) essentially comprises two posts 222,224 of substantially the same design as the post described with reference to figure 5. The two posts 222, 224 are located in opposite orientations with respective first upward portions adjacent one another.

The parallel mounting post 240 in figure 14(c) also comprises two posts 242, 244 of substantially the same design as the post described with reference to figure 5. However, the two posts 242, 244 are integral, being formed from a single length of material. The posts 242, 244 are interconnected by their anchorage portions, which are perpendicular to the upward portions in the manner described with reference to figure 4. The anchorage portion may be anchored as described previously, either directly using at least one bolt 246 as shown in figure 14(c) or indirectly using a bracket.

Figures 15 (a) and 15(b) show alternative embodiments of impact resisting posts, each comprising a double hooked post.

In figure 15(a) a double hooked post is shown generally at 260. The post 260 comprises an inner post 262 and an outer post 262' . The inner and outer posts 262,262' are each similar to the post described with reference to figures 1 and 2, and each comprise an anchorage portion 261, 261', an upright portion 264, 264', a bent portion 266, 266', and a downward portion 268, 268', as generally described previously. However, inner post is located 262 within the outer post 262' with corresponding upward portions 264, 264' adjacent and in contact with one another; and with corresponding downward portions 268, 268' parallel to but transversely spaced from one another. The inner and outer posts are further configured such that the lowest points of the downward portions 268, 268', as seen in figure 15(a), are substantially at the same height above the ground, in operation.

In operation to resist an impact the outer post 262' is impacted first, driving the corresponding downward portion 268 ' toward the corresponding portion 268 of the inner post until the associated gap between them is closed. Hence, most of the impact is resisted by the outer post, the downward portion of the inner post acting to reinforce the corresponding portion of the outer post.

The adjacent upward portions 264, 264' provide additional strength but because each upward portion 264, 264' is separately flexible, they can both flex under impact where a single post of a corresponding thickness would not be able to.

A crash barrier may be constructed using the double hooked post 260 as generally described previously, by mounting the or each barrier member to the outer downward portion 268' of each of a plurality of posts. The barrier may be constructed using one or more barrier members of known type or using hinged barrier members as described with reference to figures 10(a) to 12.

In figure 15(b), a double hooked post is shown generally at 280 with barrier members of a crash barrier in position. The post 280 is similar to the double hooked post 260 described

with reference to figure 15(a), comprising an anchorage portion 281 , 281 ' , an inner post 282 and an outer post 282' as generally described previously. The inner and outer posts 282,282' are each similar to the post described with reference to figures 1 and 2, and each comprise an upright portion 284, 284', a bent portion 286, 286', and a downward portion 288, 288', as generally described previously. However, inner post is located 282 within the outer post 282' with corresponding upward portions 284, 284' adjacent and in contact with one another; and with corresponding downward portions 288, 288 ' parallel to but transversely spaced from one another.

Unlike the post described with reference to figure 15(a), however, the downward portion 288 of the inner post extends further than the corresponding portion 288' of the outer post. The inner downward portion 288 is provided with a mounting block 290 which extends outwardly perpendicularly from the extended part such that a mounting face of the mounting block is substantially aligned with the outer face of the outer downward portion 288'.

A crash barrier is constructed using a plurality of the double hooked posts 280, by mounting an upper barrier rail 292 to the outer downward portion 288 ' of each post, and a lower barrier rail 294 to the mounting block 290. The barrier may be constructed using one or more barrier members of known type or using hinged barrier rails as described with reference to figures 10(a) to 12.

Hence, in operation to resist an impact, the affected barrier member of the lower barrier rail flexes on the inner downward portion, substantially independently of the flexing of the affected barrier member of the upper barrier rail. Generally, for many vehicles, the lower rail and hence inner downward portion will take the initial impact, this being followed by an impact to the upper rail and the outer downward portion.

The impact resisting posts described may also be used as a crash barrier gate for protecting warehouses or the like from ram raids. Figure 16 shows a simplified perspective view of a further embodiment of a such a crash barrier, where configured as a gate.

In figure 16, the further embodiment of a crash barrier is shown generally at 300. The crash

barrier comprises a barrier member 302, and two impact resisting posts 304, 306.

The barrier member 302 comprises a section of corrugated beam material. It will be appreciated, however, that the barrier member 302 may comprise any suitable material, for example rectangular hollow beam or the like. Furthermore, a plurality of barrier members may be used, arranged to form a dual barrier rail or the like.

The impact resisting posts 304, 306 comprise posts of the type described with reference to figure 5. The posts are, in operation, secured into sleeves, or like, located at an appropriate distance from one another in front of a premises requiring protection. The sleeves are robustly mounted in concrete.

The barrier member 302 is hingedly connected at a first end by a hinge 308 to a first of the posts 304 for rotational movement as indicated by arrow 'A' between an open and closed position. A first hinge flap 310 of the hinge 308 is mounted in the slot formed between the downward and second upward portions of the first post 304 using suitable means 312 such as bolts or the like. The remaining hinge flaps 313 are similarly secured to the barrier member.

The opposite end of the barrier member 302 is provided with securing means 314 for securing the barrier member to the second post 306. The securing means 314 and the second post are located for mutual engagement when the barrier member 302 is in the closed position. The securing means 314 comprises a pair of protruding brackets, which locate transversely on either side of the second upward portion of the second post. Each bracket is provided with a corresponding aperture 316 and is located for mutual alignment both with the corresponding aperture on the other bracket, and with the slot foπned between the downward portion and the second upward portion of the second post, when the barrier member 302 is in the closed position.

Hence, in operation a locking bolt of appropriate dimensions (not shown) may be inserted through the apertures, via the slot to secure the barrier member in the closed position.

Appropriate locking means 320 are provided on the downward portion, for securing the bolt

member to the second post 306 when the barrier member 302 is secured in the closed position, thereby locking the crash barrier shut. The locking means may include a conventional key operated barrel lock or the like.

Hence, the crash barrier 300 operates in the same manner as a gate, allowing an open loading bay of a warehouse, or the like to be protected whilst still allowing easy vehicle access for personnel holding a correct key.

A second securing means 324 is provided approximately centrally relative to the length of the barrier. The second securing means 324 is located for mutual engagement with an optional third post (not shown), similar to the second for providing a more robust barrier. Typically, the third post is, in operation, removably received in a corresponding sleeve when vehicle access is not required, for example at night. The barrier is then closed and locked in the closed position at both the second and third posts.

hi figure 17, a further embodiment of a crash barrier is shown generally at 400. The crash barrier comprises gate is similar to the gate described with reference to figure 16 and will not be described again in detail other than to highlight the main differences.

The gate comprises two impact resisting posts 404, 406 each of the general type described with reference to figure 5. The posts are, in operation, secured into sleeves, or like, located at an appropriate distance from one another in front of a premises requiring protection. The sleeves are robustly mounted in concrete.

Unlike the gate of figure 16, the gate comprises a plurality of barrier members 402, 402' similar to those described for the hinged crash barrier. A first pair of the barrier members 402 are each hingedly connected at a first end by a hinge 408 to a first of the posts 404 for rotational movement as indicated by arrow 'B' between an open and closed position. A first hinge flap 410 of the hinge 408 is mounted in the slot formed between the downward and second upward portions of the first post 404 using suitable means 412 such as bolts or the like. The remaining hinge flaps 413, 413' are respectively secured to each of the first pair of barrier members 402.

The opposite end of each of the first pair of barrier members 404 are hingedly connected to respective ends of each of a second pair of barrier members 402' by hinges 418, to form a pair of hinged barrier sections.

The end of each of the second pair of barrier members 402' opposite the hinged end, is provided with securing means 414 for securing each barrier section to the second post 406. The securing means 414 and their operation are similar to the corresponding securing means described with reference to figure 16 and will not be described again in detail.

A second securing means 424 is provided approximately centrally relative to the length of each hinged barrier section. The second securing means 424 is located for mutual engagement with an optional third post (not shown), similar to the second for providing a more robust barrier. Typically, the third post is, in operation, removably received in a corresponding sleeve when vehicle access is not required, for example at night. The barrier is then closed and locked in the closed position at both the second and third posts.

The respective lengths of the first and second barrier members 404, 402' are such that each second securing means are located toward the corresponding end of each respective barrier member of the second pair 402 ' . It will be appreciated, however, the lengths may be such that the hinges 418 may be located in alternative positions, for example, on the other side of the second securing means 424, or towards the first securing means 414, as indicated at 418', 418" respectively.

The use of hinged barrier sections provides additional impact protection because of the additional barrier flexibility. Furthermore, the barrier sections may be folded back on one another, when open for more compact and convenient opening, especially in confined spaces. The fold-back advantage is particularly evident for barrier hinge positions 418, 418' toward the centre of the barrier sections.