Until 1994 urban transport policy tried to cope with inexorable traffic growth by a few sporadic improvements in road capacity but, in essence, the network remained unaltered. Traffic growth did occur but at times and in places which allowed it: congestion did not 'get worse' by becoming more intense but by spreading in time and space. Organic change in the structure and size of the city was the result.

After the 1994 Rio Conference there was a widespread policy shift because of concerns about the damage to the global and local environments caused by excessive car use. The policy is now to try to fit demand onto the existing city network. This brings problems: politicians have to take hard and often misunderstood decisions, rather than being inert spectators of urban change; technical officers have to predict the uncertain results of those decisions; the public and the media will keep a hawkish eye on what is done. And, just for good measure, responsibility for the transport system is spread over a range of organisations, all with their own agendas.

It is a heady political and technical brew in which many of the policies appear impossible or undesirable. There are no painless panaceas but a plethora of potential policies in an area which affects us all.