An investigation of the relationship between traffic enforcement and the perceived risk of detection for driving offences

Monash University Accident Research Centre - Report #134 - 1998

Authors: W.A. Harrison & N.J. Pronk

Abstract:

The report presents the results of a survey of 3,700 licensed drivers in Victoria, Australia, concerning their experiences of speed and drink-driving enforcement and their perceptions of the risk of detection for speeding and drink-driving. Exploratory analyses of the data indicate that there were five groups of correlated items. These related to the perceived risk of detection for drink driving and exposure to drink driving; exposure to drink-driving and speed enforcement in general; the perceived risk of detection for speeding; the type of driving exposure of respondents; and the recency of contact with enforcement. These factors were largely independent, with the exception of the two perceived risk factors which were moderately correlated. The factor analysis results were used to investigate similarities between drivers in a cluster analysis, where it was shown that there were six groups of respondents defined in terms of their experiences with and attitudes to enforcement activity which differed on a number of other survey measures.

Executive Summary

The nature of the relationship between the perceived risk of detection and exposure to traffic enforcement is unclear, and the processes underlying the effects of enforcement on driver behaviour are unclear.

This report details the results of a survey of 3,700 drivers in four Police Districts in Victoria. The survey was conducted as part of an evaluation of a specific enforcement program, and the present report uses the data collected in the survey to investigate the relationship between exposure to enforcement activity and the perceived risk of detection for traffic offences in the speeding and drink driving domains.

The survey questionnaire included items relating to:

The perceived risk of detection for speeding during daylight and night-time hours separately;
The perceived likelihood of being checked for alcohol during daylight and night-time hours separately;
The perceived risk of detection for drink-driving during daylight and night-time hours separately;
The occupation, age group, and sex of the participant;
The amount of driving and proportion of built-up-area and daylight driving of each participant;
The awareness of road safety publicity; and
The personal experience and indirect knowledge of others' experiences of traffic enforcement.

A factor analysis of the survey data indicated that there were five groups of correlated items. These were items relating to:

The perceived risk of detection for drink driving and exposure to drink driving enforcement;
Exposure to drink-driving and speed enforcement in general;
The perceived risk of detection for speeding;
The type of driving exposure of respondents; and
The recency of contact with enforcement.

These factors were largely independent, with the exception of the two perceived risk factors which were moderately correlated.

The factor analysis results were used to investigate similarities between drivers in a cluster analysis, where it was shown that there were six groups of respondents defined in terms of their experiences with and attitudes to enforcement activity which differed on a number of other survey measures.

The final exploratory analyses investigated the nature of the relationship between survey measures and perceived risk in more detail.

The results are interpreted, in part, as having relevance to the generalisation of deterrence models to speed-choice behaviour, where it is suggested that the nature of speed-choice makes it unlikely that a deterrence model is the most appropriate way of accounting for the relationship between enforcement and behaviour.

Sponsoring organisation: Transport Accident Commission