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How can speed enforcement be made more effective? An investigation into the effect of police presence, speed awareness training and roadside publicity on drivers’ choice of speed

How can speed enforcement be made more effective?  An investigation into the effect of police presence, speed awareness training and roadside publicity on drivers’ choice of speed
Aswin Azhar Siregar


Institute for Transport Studies, University of Leeds, Leeds LS2 9JT, UNITED KINGDOM.


The effectiveness of police strategy in influencing motorists’ choice of speed must be questioned because speeding has remained a consistent factor in accidents to this day. In light of this persistence, the objective of this research is to develop more effective speed enforcement by investigating the effects of police presence, motorists’ training, and roadside publicity on motorists’ choice of speed. These factors are the most widespread interventions implemented by police all over the world, although only few have investigated how effective these interventions in fact are either as a single or as a combined intervention.

This study was conducted in Indonesian road and applied a factorial experiment design where police, training and publicity were operated as the intervention factors. Participants’ responses were recorded during driving throughout prearranged test routes. Further, a traffic survey and questionnaires for motorists and police officers were utilized to support the study’s results.

A survey of motorists shows that they are aware of the consequences of speeding, although prefer softer approaches to handle it, while a survey of police forces shows a high level of satisfaction for existing measures, including the new proposed speed enforcement program. There are still many aspects yet undiscovered that correlate to public attitude and police officer job satisfaction to current speed enforcement methods.

One important finding of this research is the discovery of a three-way interaction effect on dual carriageways, which means that the addition of training and publicity to police interventions increases the effectiveness of speed enforcement. However, on single carriageways, the only significant effect was produced by police presence. The combination of three factors not only reduced mean speed by 14% and 10% on dual and single carriageways respectively, but also increased compliance by 72% and 33% until the end of test route. The estimated fatal casualty reductions are 52% and 33% for single and dual carriageways. Surprisingly, the training as single factor has increased travel speeds on dual carriageways, although the effect has changed drastically when combined with police and roadside publicity. This finding could only be justified by the fact that training increase motorists’ confidence. Thus, we need guidance to avoid the confidence bias. Also, different distances of Halo effect were observed on both routes in relation to combination of intervention applied.

Finally, the result shows that there is potential for further development of speed enforcement programs by combining training and roadside publicity into police enforcement. In addition, this study also proposes a number of policies so that enforcement agencies can increase the effectiveness police enforcement.