In this paper the results from a field experiment (conducted in 2012) are presented, in which 3 regional police units in the Flemish region of Belgium each tested a particular combination of a speed control (with mobile radar in an anonymous car) with communicative signage. The goal of this paper was to scientifically evaluate frequently used field set-ups. The following set-ups were tested in one week: (1) police unit 1: speed control with and without a static feedback sign placed after the control; (2) police unit 2: speed control with and without a digital feedback sign placed after the control; (3) police unit 3: speed display followed by a second speed display further along the road section. During certain time frames, speed control took place in between both signs. All tested field set-ups generated significant reductions in the speed level. Studying the effect of the different variations for each set-up reveals that the effect of the speed control is generally larger in combination with the signage alongside the road. After the period during which the police activities took place, speed levels again reached their initial level. Based on the before–after analysis, only in police area 2 was a small ‘time halo-effect’ found. To generalize results from this pilot study, repetition of tested set-ups in the field is recommended as well as testing on a larger scale.