The goal of these devices is to absorb the kinetic energy of the vehicles that hit them. Some of the devices work by redirecting the vehicle away from the danger or hazard. This includes making them veer away from machinery and workers who are on the side of the road or in the road. They are very effective when they are placed in stationary locations. However, it is also possible to utilize a truck-mounted version of the device. These will typically go on the back of vehicles that have a higher chance of being hit from behind, such as maintenance vehicles.