A comparison of the effects of posted feedback and increased police surveillance on highway speeding.

A counterbalanced, reversal design was used to compare the effectiveness of posted feedback and increased police surveillance in reducing speeding on two urban highways. Drivers' speeds were measured using a concealed radar unit. During public posting, a large highway sign, which listed the percentage of drivers not speeding during the preceding week and the best record to date, was erected on each street. Use of the feedback sign alternated with periods of baseline and periods of increased police surveillance and ticketing. During increased police surveillance, highly visible, stationary police radar patrols were established along the highways for either 30 min or 60 min per day, 5 days per week. Results indicated that although public posting was highly effective in reducing the percentage of speeding drivers, increased police surveillance was not. Thus, since the feedback sign required only 30 min per week to maintain, public posting was at least 10 times more efficient in controlling speeding than was police surveillance and ticketing.