Speed Calming Using Vertical Deflections in Road Alignment

In densely urbanized areas with intensive land uses, traffic calming is a vital safety countermeasure to avoid violation of permitted speed-limits in hazardous areas such as: un-signalized at grade intersections and upstream of surface pedestriancrossings at or nearby densely land-uses. Previous research showed that speed calming is done by horizontal or vertical deflections. Horizontal deflections in road alignment could be achieved through narrowing carriageway width, adopting horizontal alignment to prevent over speed, etc. while vertical deflections in road alignment could be achieved through instillation of speed humps upstream to the required speed calming or temporary work-zones locations. This paper focuses on determining actual traffic performance up and down streams of speed calming countermeasures using vertical deflections in road alignment to study the influence of their physical and geometric characteristics on traffic performance, in terms of speed profile and also to extract some guidelines for their most suitable locations.