Abstract: Two rails are disposed in a direction of wheel travel and joined at their ends so as to permit continuous rolling of the wheel from one rail to the other. These rails maintain the wheel at a predetermined elevation, and the ends have a gap therebetween. The wheel is supported in a region overlapping the gap at an elevation equal to the predetermined elevation of the rails without any significant drop of the wheel into the gap. The wheel may be elevated to maintain the predetermined elevation by contacting a rolling surface location thereon, differing from that normally contacted by at least one of the two rails. The wheel may also be elevated over the gap by a support positioned along the side of at least one of the two rails that extends outward away from the end of the rail in the direction of wheel travel.

Abstract: An energy absorber which comprises in cross-section at least one limb of rubber-plastic composite material comprising a layer of rubber and a layer of plastics, said layers being united together and each extending substantially in the direction of the length of the limb, and the layer of plastics material being capable of absorbing more energy than the layer of rubber during deformation of the limb by bending or buckling.