Extent of highway capacity loss resulting from road humps

Abstract

Road humps are traffic calming devices placed across road widths solely as speed reduction mechanism. They include, speed cushions, junction tables, road humps. Whilst it is clear that 75mm deflection like road humps would reduce speed to 20km/h on average, determining their impact on traffic flow rate has often been poorly reported. Based on the hypothesis that on any route with humps mean stream flow will lie within highway capacity loss envelope; moving car observer survey method was used to determine mean stream flows as well as a volumes and speeds of ‘with and without’ road humps sections. The studies were carried out under day light and dry weather conditions so as to eliminate their effects. An important part of the study is employment of dynamic passenger car equivalent values for the road sections. Results show significant highway capacity loss and the mean traffic flows lying within capacity loss envelope. The study concluded that although road humps are effective mechanism for vehicle speed reduction, their resultant highway capacity loss is significant.