Transport Supply, Demand and Travel Time
Within an urban area, transport supply (A) tends to be stable throughout
the day, with the exception of public transit that adjusts its services
(namely in terms of frequency) to cope with peak hours. Transport demand
(T), on the other hand, varies considerably for several reasons, mainly
linked with commuting. Typically, transport demand exceeds transport
supply twice during the day (morning and afternoon peaks). The resulting
congestion significantly increases travel time.