Raised Crosswalks And Their Design Features InTraffic Calming

Abstract

A road hump, or speed hump, is a traffic calming device used to reduce vehicle speed and volume on residential streets. Road humps are placed across the road to slow traffic and are often installed in a series of several humps in order to prevent cars from speeding before and after the hump. Speed humps are used in locations where very low speeds are desired and reasonable. Speed humps are typically placed on residential roads and are not used on major roads, bus routes, or primary emergency response routes. In Italy, the road humps are often built in the shape of raised crosswalks (RCWs) and they are generally placed both close and between intersections. This paper deals with the analysis of observed data on a sample of RCWs located in Tuscany, central Italy. Such data were referred both to geometry characteristics of the single raised crosswalk and recorded differences in vehicle speeds before and after it. Speed data were gathered using two automatic radarrecorders for each one of the sampled raised crosswalks. All the collected data were analysed firstly through statistical tests in order to assess their homogeneity or not between different locations and various types of roads; secondly, through modelling software to obtain a generally valid formulation to evaluate the functionality of the device. Finally, we were able to make some conclusions and highlight design aspects. On the one side, RCWs with similar geometries have similar effects on the lowering of vehicle speeds, regardless of local conditions (location, road geometry, driver behaviour, etc.). Moreover, recent developments of the research show that raised crosswalks installed in a series have an influence on the speed reduction in function of their number and their distance. On the opposite side, the effects of raised crosswalks with smaller heights (less than 6 cm) show clearly a very low influence on vehicle speed variations.