| 1. | An improved concrete block designed to serve as a roadway or lane defining member, said block (1) having an elongate concrete body with an essentially triangular crosssectional shape including one bottom face (2) and two preferably symmetrical side faces (4), c h a r a c t e r i s e d i n t h a t each side face (4) of the block is formed in the area closest to the bottom face (2) u/ith a straight threshold portion (5) sloping at a gradient of 1:5, said portion being interconnected to a second straight portion (7) sloping at a gradient of 1:7 via an essentially circularly arcuate concave portion (6). |
| 2. | An improved concrete block as claimed in claim 1, c h a r a c t e r i s e d i n t h a t the blocks have a length cf appr. 2 meters. |
| 3. | An improved concrete block as claimed in claim 1 or 2, c h a r a c t e r i s e d i n t h a t the blocks are interlocked with the aid of a means arranged to connect to one another interlocking means mounted on the opposing end faces αf the blocks. OMPI WIPO". |
The subject invention concerns improvements in concrete blocks designed to serve as road barriers, and roadway or lane defining members. The blocks have an elongate concrete body u/ith an essentially triangular cross-sectional shape including one bottom face and tu/o preferably symmetrical side faces ' .
In four-lane traffic routes median barriers and roadway defining members are often used to prevent vehicles travelling in one direction from entering the lanes in which the vehicles are moving in the opposite direction. In case of accidents caused by skidding, aqua-planing, tyre punctures or careless driving such road barriers may prevent the vehicles involved in the accidents from colliding, head-on with oncoming traffic. •The barriers and roadway definin-g .means usually consist of concrete plinths to which horizontal steel beams are attached. One disadvantage with barriers and roadu/ay defining members of this kind is that the steel material of the beams make them somewhat resilient, uiith the result that vehicles colliding with the barrier at an oblique angle of impact as a rule mill be thrown back towards the vehicles travelling in a direction parallel with that of the colliding vehicle, or even be thrown off the road. A comparatively harmless accident therefore may have very serious consequences.
Road barriers of the kind referred to above are permanently anchored, that is, they cannot be opened up to allow the traffic to be rerouted onto adjoining traffic -lanes in case one lane or roadway is blocked off. Nor is it possible to use this kind of road barriers to protect the workmen engaged in temporary road work.
It is also known to use concrete t»ldis s as median barriers to separate opposing traffic roadways. The blocks
have a triangular cross-sectional shape and may be moved temporarily to divert traffic in case of accidents and may also be used as protections during road work. Cases have been reported, however, when as a result of aqua-planing or skidding vehicles hit a row of concrete blocks at an acute angle and roll over the blocks and onto the lane of oncoming traffic, thus causing serious accidents. Also when vehicles hit the concrete blocks at low speeds the damages to the front part of the car chassis have proved to be so serious that the car has to be towsd from the place of accident and be repaired at great expense.
The purpose of the road block in accordance with the subject invention is to prevent vehicles hitting the barriers from rolling over the barriers, from being thrown into the lane of parallel traffic or from being damaged to such an exte,nt that the vehicle must be towed away. The road block is furthermore intended for use in temporary road uiork. It is also designed to allow individual, damaged blocks to be easily replaced, to allow water runoff, and to be rapidly and easily dismantled and removed for asphalting and other paving work or when an opening is desired through the barrier. The block in accordance with the invention furthermore serves as a blind, screening off glaring and blinding lights from oncoming traffic. In addition, it is designed to allow road signs, light poles and noise-reducing mats to be mounted thereon. To achieve these purposes, the block in accordance with the subject invention is characterised in that each side face of the block is formed in the area closest to ^ ,
illustrated in the accompanying drawings, wherein
Fig. 1 is an end View α a concrete block in accordance with the invention,
Fig. 2 is a broken view of two blocks in accordance with the invention with means for inter¬ locking these two blocks together, and
Fig. 3 shows two interlocked blocks. The concrete block 1 is supported on feet 3 formed on a bottom face 2, said feet being provided to allow water to flow freely underneath the block. The side faces 4 have a profi led shape incorporating a lower straight threshold portion 5, a concave arcuate portion 6 and an upper sloping portion 7 on either side of the block. The gradient of the slope of the threshold portion 5 is 1:5. It is designed to turn the front wheel of a vehicle Kitting the block at a small angle of impact • in a direction in parallel with the lengthwise extension of the barrier. As a result, the vehicle will continue its travel alongside the barrier of concrete blocks without being damaged or causing serious accidents.
When t a angle of impact of the vβ icle is larger and the speed higher the vehicle will "climb" over the threshold portion 5 up onto the concave arcuate portion 6. This will consume some of the kinetic energy of the vehicle. When the angle of impact is large the vehicle will "climb" high up onto the sloping .portion 7 the gradient of which . is 1:7, and the majority of the kinetic energy of the vehicle will then be consumed. However, the deceleration is not so abrupt that vehicles behind run the risk of driving into the vehicle colliding with the barrier, which might otherwise have resulted in a chain of collisions.
When it is "climbing" up the barrier the vehicle will automatically be guided in a direction in parallel with the barrier and the rear wheel of the vehicle will follow the front wheel up onto the barrier. In the initial
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phase a considerable amount of the kinetic energy will be absorbed by the tyres and the suspension of the vehicle. A further amount of the energy may be absorbed through the concrete blocks because the latter, being interlocked into a long chain forming the barrier, may be displaced somewhat laterally on the feet 3.
The means for interlocking the blocks 1 to one another are shown in Fig. 2 and comprise a tube 8, a retaining plate 9 and tuiα nuts 10, At each end the concrete blocks 1 are provided with a centrally located and verti¬ cally extending groove 11. The groove 11 terminates short off the base face 2 of the block and is provided at its lower end with a vertically extending pin 12 which is directed upwards. When two blocks 1 have been placed end-to-end the two grooves 11 of adjoining blocks together form a channel in which the tube 8 may be inserted from above. When the tube 8 is inserted fully into the channel it encloses the two pins 12 which are connected with rein¬ forcement irons 13 cast into the block. At the upper end of the channel and spaced from the latter there is provided a threaded pin 14, one adjacent each side face of the block. The retaining plate 9 is formed u/ith apertures 15 matching the pins 14 and the plate may be locked to the latter with the aid of the nuts 10. Each end face of the blocks is slightly bevelled, which allows the blocks, being inter¬ connected at the centre line, to be locked together along the radius of a curve.
The interlocking means in accordance with the invention are capable of withstanding considerable stress without breaking while at the same time they allow inter¬ locked blocks to be rapidly and easily disconnected from one another. Road signs, light poles and noise-reducing mats may be mounted at the interlocking means.
The concrete blocks in accordance with the subject invention have been tested by the Swedish National Road and
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Traffic Research Institute (l/Tl). The tests show that vehicles colliding with a barrier formed by blocks in accordance with the ubject invention as a rule may be driven away from the place of the accident without further. Only in cases of extremely heavy collisions it is necessary to tow the vehicle away. However, not even when the impact from the vehicle colliding with the barrier is extremely strong has one been able to detect any tendencies in the colliding vehicle to bounce away from the barrier in a direction towards the cars travelling in parallel lanes or to roll over the barrier and into the lane of the oncoming traffic.
The invention is not limited to the embodiment described in the aforegoing but various modifications are possible within the scope of the appended claims.
For instance, the height and width dimensions of the concrete blocks may differ, the essential feature of the invention being the provision in the block of a lower straight threshold portion sloping at a gradient of 1:5, a con- cavely arcuate portion 6 and an upper sloping portion 7 the gradient of which is 1:7.. Other interlocking means than those shown to link the blocks to one another are possible.
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