Influence of Speed Bumps Design on Vehicle Safety

During a journey motor vehicles are forced to overcome different types of irregularities in the pavement. Such irregularities can be random or introduced for a specific purpose, such as asphalt protrusions and transversal bands of rubber, which have been installed into all sorts of avenues and roads open to traffic. Generally, these elements are included in a stretch of road to slow down the vehicle velocity at certain sites, such as pedestrian crossings. However, the influence of speed bumps installed shows other additional effects which must be studied to ensure the safety of vehicles and pedestrians. In some cases, it is found that, passing over ridges and transverse bands at a speed below the limit defined by law, the vehicle is damaged or the tires lose grip with the pavement, precluding any kind of braking or turning maneuvers. Such phenomena indicate that this element is not properly sized, or the placement is not appropriate, becoming counterproductive for traffic safety. In spite of the importance of these consecuences derivated from these elements they haven’t been studied deeply enough and there are very few paper about this subject. In order to analyze the actions generated by the overcome of these irregularities on the different components of the vehicle and its occupants, the problem has been studied not only using computer simulation but also by means of experimental testing on a real vehicle where accelerometers were installed in order to check the severity of the bumps. CarSimTM has been the simulation software used to calculate vehicle dynamic forces on the tires and suspension system and the accelerations and displacements that are applied to the vehicle. To characterize the behavior of a vehicle when is driven over one of these obstacles, it is necessary to study several parameters such as: speed, geometry and dimensions of the bump, and the type of vehicle and its suspension. From this information it is possible to establish a set of guidelines for the proper design and installation of speed bumps in different roads.