Abstract
An experiment aimed at investigating the memory effect of the presence of an enforcement symbol is described. The experiment consisted of an enforcement symbol being present on chosen sites. The enforcement procedure was used during one peak period and one off peak period as it was thought that the behaviour of commuter and non-commuter drivers may differ. The results showed that for commuters drivers on some sites it is possible to produce a memory effect of enforcement. The effect lasted for at least three days after the enforcement had been removed.