Speed humps and speed tables: Externalities on vehicle speed, pollutant emissions and fuel consumption

Speed hump/table are devices used on roadways with the objective of reducing vehicular speed. Nevertheless, the effects of said devices on traffic streams are not that clear. Therefore, through descriptive statistics and approximations of linear models, an analysis was carried out on a collector street, as a case of study, taking into consideration the shapes and spacing of bumps, and pollution and fuel consumption of vehicles. The results indicate that the shape and size of the speed control devices are the most important factors for efficiency in reducing maximum speed between devices, achieving a reduction of 50%–75% with speed humps, and a 10%–65% reduction of maximum speed in those which are trapezoidal shape (speed tables). The spacing between speed control devices does not significantly effect a vehicles speed upon passing over said devices, but it does have an impact on pollutant vehicle emissions and extra gasoline consumption. The estimated models to calculate the speed control device characteristics can help to determine which geometric shapes to use when deciding about type and placement of the device, depending on the requirements of a particular thoroughfare.