A Multiple Event Response Trailer (M.E.R.T.) is a lightweight, rapidly deployable trailer designed to carry traffic control and safety equipment for emergency road closures, accidents, or public event... A Multiple Event Response Trailer (M.E.R.T.) is a lightweight, rapidly deployable trailer designed to carry traffic control and safety equipment for emergency road closures, accidents, or public events. These trailers allow police or highway crews to quickly set up barriers, cones, and, in some models, solar-powered message signs to secure scenes and manage traffic flow efficiently