FIELD INVESTIGATION ON THE EFFECTS ON OPERATING SPEED CAUSED BY TRAPEZOIDAL HUMPS

The most effective way to reduce vehicle speed on urban low volume roads, such as residential streets, is the installation of traffic calming systems such as speed humps and tables. In those roads in which these measures are applied, a reduction in traffic volume and accidents is generally observed, with clear benefits for pedestrians, bicyclists and residents. A study was undertaken in order to investigate the effectiveness of trapezoidal speed humps in reducing the operating speed and to highlight the main factors influencing this type of traffic calming system. An urban residential street 1.8 km (1.12 miles) long, characterized by the presence of 12 humps, was monitored during two months (between October and December 2006) and several speed profiles were collected with different measuring systems. All data were processed in order to present a statistical discrete operating speed profile, making it possible to derive a model which links hump spacing, lane width and operating speed. Such a model can be a valuable tool for road engineers in predicting, for design purposes, the effectiveness of trapezoidal speed humps in similar situations.