The influence of speed bumps heights to the decrease of the vehicle speed – Belgrade experience

• Compared to the state before the speed bumps were installed, statistically significant speed reducing was achieved.
• The values of the measured speeds became lower as the speed bumps height raises.
• At locations where larger pedestrian presence is expected, speed bumps can successfully reduce the speeds of vehicles.
• The implementation of traffic calming measures, such as speed bumps, significantly contributes to the safety of pedestrians.

In the inhabited zones where a large number of pedestrians and other vulnerable road users are expected, like school zones, it is necessary to decrease the speed to such a level that the risk of vulnerability is the lowest possible. One of the commonly accepted and often implemented speed decrease measures is vertical raising of the road pavement (speed bumps, speed humps, etc.). This work shows the influence of speed bumps of different heights (3, 5 and 7 cm) to the decrease of vehicle speed. Speed measurements had been done before speed bumps were installed, 1 day and 1 month after the installation. Applying ANOVA analysis and post hoc analysis, using Tukey–Kramer’s multiple comparison test, a comparison was made of mean, 50th percentile and 85th percentile speed, before and after speed bumps setting. It has been shown that there is a significant speed decrease on the places where speed bumps were set, compared to the period before setting. Based on the research results, it was suggested that on the locations where vulnerable road users are extremely endangered, speed bumps 5 and 7 cm high should be set, whereas at less endangered locations speed bumps 3 cm high could be set. Also, it has been shown that the effects of speed bumps on speed decrease are enduring, because there has not been any significant deviation in vehicle speeds neither 1 day nor 1 month after speed bumps setting.