The effect of sanctions and police enforcement on drivers' choice of speed.

A Stated Preference survey of speed choice on Norwegian rural roads with 80 km/h speed limit was made by the roadside in order to determine which factors most strongly influence this choice. The aim was to study deliberate speeding to identify any correlations between speed choice and (1) the drivers' perception of the level of police enforcement, (2) penalties for speeding and (3) the speed choice of the other drivers on the road. Drivers were asked about their perception of these variables before being presented to nine hypothetical situations for which they were asked about the most likely speed to choose. Speed measurements were conducted before the interview, but without informing respondents of it. A total of 408 interviews were made. Drivers made bad guesses when estimating the level of enforcement, but had more realistic views of the sanctions given for speeding, as well as the general speed levels. The largest speed reducing effects on individual speed choice were found by either making most other drivers on the road reduce their speed, or by substantially increasing enforcement. Stricter sanctions seem to affect the speed choice only marginally.