Abstract: A crash attenuation system having an improved, controlled axle release mechanism for a truck trailer mounted attenuator. The axle release mechanism has an axle release insert disposed within an outer bursting tube which is urged downstream by a mandrel resulting in controlled shearing of the fasteners passing through different size elongated slots in the insert and retaining the insert within the bursting tube. Differential shear forces cause the fasteners to shear at different times as the insert is urged downstream resulting in a controlled release of the breakaway axle assembly.

Abstract: A trailer mounted crash attenuation system has an impact head assembly, a bursting tubular trailer frame member, and a breakaway axle assembly. Upon impact by a vehicle, the head assembly is urged forward bursting the tubular frame of the trailer. As the impact continues, the head assembly contacts an axle accelerator rod which results in the disengagement of the axle, trailer tire, and fenders from the trailer frame member. Impact energy is dissipated by the controlled deceleration of the vehicle as it moves forward through the attenuator system.

Abstract: A crash cushion system to envelop at least one bridge pier. The system has two impact heads, one facing one traffic flow direction and the other facing an opposite traffic flow direction. The heads are connected to multi-stage box beam energy absorbers which are in turn connected to a tubular frame structure which envelops the bridge piers. The frame is spaced apart from the face of the pier sufficiently to avoid an impacting vehicle's snagging the frame and contacting the pier structure. Anchorage cables to stiffen and support the sides of the envelope are positioned inside the frame's parallelogram shape.

Abstract: A portable crash attenuation system having a trailer frame and an energy absorption mechanism attached thereto. The absorption mechanism has a first stage pivotably connected to a second stage and the second stage is pivotably connected to the frame. By pivoting the stages about hinges the attenuation system may be folded from an extended, deployed position or mode to a shortened transit mode for easy relocation of the entire attenuation system.