A
Jersey barrier or
Jersey wall is a modular
concrete or plastic barrier employed to separate lanes of
traffic. It is designed to minimize vehicle damage in cases of incidental contact while still preventing the crossover case of a head-on collision. Jersey barriers are also used to reroute traffic and protect pedestrians during
highway construction, as well as temporary and semi-permanent protections against landborne attack such as suicide vehicle bombs. A Jersey barrier is also known in the western United States as
K-rail, a term borrowed from the
California Department of Transportation specification for temporary concrete traffic barriers, or colloquially as a
Jersey bump. Plastic water barriers of the same general shape are also now commonly referred to as Jersey barriers.