Various types of barrier used to prevent injury and damage being caused due to vehicles leaving the roadway are described. The types dealt wit are those designed to be effective against the impacts of passenger cars and similar sized vehicles. These include concrete kerbs and post mounted barriers, which have as horizontal elements beams of concrete and corrugated metal and in some cases strung cables. All these types nomaly act the deflect the vehicle. Other types which act only the reduce the vehicles speed without changing its direction are also described. Particular mention is made of otherwise conventional roadside barriers which have been adapted for use on bridges and central carriage way dividers (medians) as well as types developed specifically for use in such situations. Results and descriptions are given of tests designed to investigate the dynamic properties of various designs by means of impact testes using both full-sized vehicles and scale models. Up to the present no fully comprehensive testes have been reported as a result of which direct comparisons may be made between all the available barriers. The greater part of the work has been done using much heavier cars, mostly American, than are common to this country. Points which need further consideration include the whole question of the theoretical aspects of barrier-vehicle interaction during a collision as well as more detailed points such as the importance of the soil strength on the behaviour of post-mounted types.
Samenvatting