Buses are often perceived to be a cause of traffic congestion, or at least a contributory factor. This is often the case where services are unregulated and provided by a large number of small operators, particularly when small vehicles are used.
Compared to private transport, buses require less road space per passenger, and should therefore cause less congestion. However, excessive dwell times, poor driving, inappropriate vehicle size or type, and an excess of vehicles often result in increased congestion.