Crash barriers can be classified on the basis of their design and implementation. Guardrail, wire rope safety barrier, crash cushions and high containment barrier are a few that can be seen on roadways. All the crash barriers work on a similar principle, they are designed to absorb the impact of the vehicle going off track and hence help it get on to the road again without letting it lose its balance.

At times, the crash barrier to be used on a roadway is determined by the kind of vehicle traffic the roadway gets. For example high containment barriers are put up on the roadways with a large traffic volume of heavy vehicles. Then, crash cushion is specifically designed to protect motorists from impacting the end of concrete barriers and toll plazas. Guardrail is the most commonly seen crash barrier but has a history of highest injury and fatality in a fixed object crash. This is where wire rope safety barrier scores over guard rail as it consists of wire ropes and is flexible.

Though the crash barriers prevent several accidents everyday, they sure don't prevent all of them. There have been incidences of fatalities, which were mainly attributed to the design and material of the crash barriers. Most of the roadways get all types of automobiles and therefore it becomes difficult to decide on the height and strength of the crash barrier. For, a motorbike can slip under the barrier that's meant to keep a car from going off track, while a big truck may trip well over the same barrier.

As a step towards ensuring safe road travel, road safety products are first tested and then put up on roadways. The crash barriers are tested in accordance with the guidelines mentioned in National Cooperative Highway Research Program (NCHRP) Report 350, ?Recommended Procedures for the Safety Performance Evaluation of Highway Features?.

These guidelines are based on the findings of continuous road safety researches and are subject to revision.