Recurring Congestion
A typical daily urban commuting profile involves with two peak hours, morning and afternoon, which are recurring on a regular basis (on weekdays). Under normal circumstances, the transport system has a fixed capacity which remains constant throughout the day. This capacity is an outcome of road characteristics such as the number of lanes and operational constraints such as the mix of vehicles and speed limits. Congestion occurs when the amount of traffic exceeds the design capacity, which is commonly the place during the morning and the afternoon peak hours. A common issue is which level of capacity should be provided considering the daily distribution of traffic. A capacity which is too high would be expensive to provide although it would offer the benefits of limited congestion. Limited capacity would be linked with enduring congestion and negative economic externalities.