ABSTRACT
At one level, public policy-making on sustainable transport is straightforward, as it is more or less taken for granted that once a policy decision has been made the policy will be implemented, and the people will respond with the expected changes in behaviour. When the results of a policy fall short of their expectation, the people are blamed. Individuals regularly refuse to behave in ways that the policy-makers would prefer. This gap between the assumptions underlying policy measures on the one hand, and the behavioural responses by individuals on the other, is normally referred to as the policy behaviour gap. With reference to the gap between policy measures and behavioural responses to congestion, Salomon and Mokhtarian (1997) point to the large set of alternative strategies that individuals have at their disposal to avoid the expected behaviour. But ‘non-rational’ behaviour by the public may also be reinforced by poor implementation whereas the measure does not accomplish what was intended.
