The Effect of Speed Control with a Mobile Radar With or Without an Advanced Warning Sign: A Statistical Analysis on Speeding Behavior

Abstract

Speeding is an important risk factor in road safety. Generally, this risk factor plays a role in one out of three fatal crashes. Speed enforcement is one of the measures to tackle this problem. In this paper, the authors investigate the effect of a stationary police control in an unmarked police car equipped with a mobile radar with and without an advance warning sign alongside the road section. These two methods were tested on two road segments of regional roads (70 km/h and 90 km/h) in the Flemish region of Belgium by means of two field experiments. Since the use of a warning sign raises the visibility of the covert speed control the authors assume - partly based on previous research - that the effect on speeding behavior will be higher and longer lasting (than without the advance warning sign). The effect of both methods is evaluated by means of descriptive analyses, significance tests and multiple linear regression analyses. In this paper, the authors present the results of these analyses with respect to a frequently used speed behavioral indicator namely the 85th percentile of speed (“V85”). Analysis of the general effect of both enforcement methods, show a larger effect of the speed control with advanced warning sign (- 10 km/h) than for the speed control only (- 5 km/h). Results with regard to the effect in time are less conclusive. However, regression models, show only a longer lasting effect for the combination of the advanced warning sign with the speed control.