Respecting a speed limit and its effectiveness in a traffic calming zone

Abstract

The purpose of the study was to test the level of respecting the speed limit by drivers of vehicles in a traffic-calming zone that was not formally designated, located in a part of an old city in a middle of the Polish city. Due to the historic assets in that location, the applied means of traffic calming included only legal-organizational means, i.e. local speed limit signs. The analysis was carried out of vehicles speed in selected measuring sections; next, the level of respecting speed limits by drivers was determined. The results proved that just installing the speed limit signs at entrances to zones or at priority to the right intersections are insufficient to obtain the required speeds. The tests revealed that in all tested sections, drivers exceeded the speed limit of 30 km/h. An average speed varied from 32.1 km/h to 37.1 km/h, with the 85% quantile of speed amounting from 36.1 km/h to 42.7 km/h. A large percentage of drivers who exceed the speed limit was recorded, which was from 35% to 90%. The lowest percentage of drivers exceeding the maximum speed was recorded in sections where the surface was made of cobblestone (only 10%). This stemmed from the fact that in order to obtain the driving comfort, the drivers were forced to reduce the speed significantly. The results of tests show explicitly that in order to obtain desired traffic conditions from the safety perspective, it is necessary to apply physical means of traffic calming that force drivers to reduce speed. Such measures should include: An adjustment of the traffic corridor geometry in a general layout, narrowing a lane, speed bumps, raised speed tables at intersections, and raised pedestrian crossings. The applied traffic calming measures, including but not limited to areas that are subjects to the conserver's supervision, should meet high functional, engineering, and visual standards, and be a harmonious part of the historic surrounding.