The effectiveness of speed humps as traffic calming for accident reduction

Abstract

eThekwini Municipality has been allocating millions of Rand each year for speed humps as a traffic calming measure, to curb rat-running and ensure pedestrian safety in the city. Since 2012, the City has spent R42.1 million of its capital budget on speed humps. Despite all traffic calming efforts, there haven’t been significant changes in the city’s total accidents. Between 2000 and 2015, the City’s total crashes have never been below 50 000 per annum. In terms of injuries, the same trend can be observed. Person injuries have been increasing year-on-year since 2012. This research used information available to assess changes in specific roads, i.e. roads that have been traffic calmed. The study looked at accidents before and after the implementation of speed humps. Speed humps have been proven to reduce speed of vehicles (Vanderschuren & Jobanputra, 2009). Dixon and Jacko (1998) conducted a before and after study in The Netherlands to investigate changes in driver behaviour due to implementation of speed humps. This research showed that there was a 40% decrease in travel speeds after speed humps were installed. Another study by Ponnaluri and Groce (2005) showed that speed humps reduce mean speeds, median and 85th percentile speeds. In Belgrade, Serbia a study showed that speed humps reduce speed and that the design (height) of the speed hump also affects the extent of this change (Antić et al., 2013). This paper assessed the impact of reactive (responsive to requests) traffic calming in the form of speed humps using accident data. The assessment looked at changes relating to the number of crashes before and after implementation of speed humps, it will also focused on changes in the severity of accidents involved. The research analysed changes in relation to the types of accident involved, particularly pedestrians.