THE GEOGRAPHY OF TRANSPORT SYSTEMS
Source: adapted from Barber, G. (1995) "Aggregate Characteristics of
Urban Travel", in S. Hanson (ed) The Geography of Urban Transportation,
2nd Edition, New York: The Guilford Press, p. 92.
Urban Travel by Purpose and by Time of the Day
The above figure is a typical representation of urban travel by purpose and by time of the day, notably in North American cities. Two peak hours around 8h00 and around 17h00 corresponding to home-to-work trips are prevalent. Shopping trips mostly occur during the afternoon, while social/recreational trips are mainly occurring in the evening. This unequal distribution of movements is often creating congestion at "peak hours". Three major strategies can be implemented to alleviate this problem:
- Flexible Work. Alter the times at which people are arriving at and leaving work. This would level out the distribution of trips. For several activities such as retailing this strategy is difficult to implement since they require synchronized work shifts.
- Land Use Modifications. Change the employment distribution to alleviate traffic in most congested areas and spread the traffic around. Since the 1950s, several activities have been relocated in suburban areas, notably nearby highway interchanges. However, in several instances this only increased or moved congestion problems elsewhere.
- Constraining Transport. Private cars can be denied access to central areas or tolls (congestion pricing) can be used. In a number of cities, traffic is getting increasingly controlled such as in Singapore where car purchases are controlled (through a system of quotas) and where access to downtown is restricted by a permit system.