Traffic jams are caused by too many vehicles on the road at the same time, slowing speeds and increasing trip times. A traffic jam, also known as a traffic congestion or traffic snarl-up, occurs when the number of vehicles using the roads increases and exceeds the road's capacity. Potential solutions to reduce traffic jams include widening roads, adding bus lanes, building new tunnels or ring roads, developing light rail networks, or adjusting traffic light timing.