Acceleration/deceleration lanes (also known as speed change lanes) provide drivers with an opportunity to speed up or slow down in a space not used by high-speed through traffic. On freeways and some major streets, the speed change between the mainlanes and the adjacent streets can be substantial and cause stop-and-go traffic and more collisions for the main vehicle flow. Dedicated acceleration lanes allow cars that have turned onto the main road to speed up to match the flow of traffic.