Guard rails have been designed to prevent cars from colliding with obstacles behind the rail. They absorb energy and control the trajectory of the vehicle in collision with the rail. Existing rails have not been designed for collisions by PTW's and may cause severe injuries to their riders.
The first studies on collisions of PTW's with guard rails have concentrated on the design of the rail post as a short term, low cost solution. A recent German study tested several guard rail designs intended to reduce injuries to motorcycle riders . The full scale collision tests showed two problems: a motorcycle sliding against the rail with the rider hitting the rail post and/or sliding under the rail and an upright motorcycle with the rider hitting or being trapped by the upper part of the rail. The experimental devices were designed to be retrofitted to existing rail designs. The test results showed the devices to be effective in preventing injuries to the rider and in controlling the trajectory of the motorcycle. They have not been tested yet in collisions by a car.
The costs of fitting these devices can be reduced by selecting road sections where collisions by motorcycles is more frequent, i.e. in tight curves in rural areas .