Speed bumps are one of many traffic devices used to slow traffic and break up congestion. However, many studies show that speed bumps are not overly effective. In fact, of all the parameters investigated, speed bumps are only advantageous in one situation, regarding child safety. Speed bumps have been found to promote bad driving and cause other traffic problems. Though speed bumps may sound good on paper, they do not work as planned when put in place on roadways.
A study in Oakland, California, investigated the number of children hit by an automobile in a neighborhood without speed bumps and those children that live within one block of a speed bump. The study found that children who lived near a speed bump were less likely to be hit by an automobile, as much as half less likely. Because of this study the city of Oakland installed more than 2,000 speed bumps in residential streets.
Several studies have investigated the speed bumps' effectiveness in controlling speed. It was found that speed bumps are not the most effective tool for speed control because drivers tend to use odd maneuvers to avoid the speed bump, which effectively encourages poor and unsafe driving. More than half of all drivers and more than 85 percent of motorcyclists will move to the opposite or parking lanes to avoid going over the speed bump. It was found that speed cushions and humps -- much longer from front to back (typically 10 to 12 feet) than speed bumps -- were more effective at promoting safe driving and controlling speed.
Studies have investigated the effect of speed bumps on emergency response times. As with any other vehicles, emergency vehicles such as fire trucks and ambulances, must slow down to go over speed bumps. Going over the speed bumps at the posted speed is not safe for emergency vehicles because they are much larger and heavier than most automobiles. The driver would experience discomfort and the suspension would not absorb all the shock. This is a distinct problem for emergency vehicles transporting injured personnel. Therefore, speed bumps, which typically are not designed with emergency vehicles in mind, increase the response time of emergency vehicles.
Speed bumps are one way to attempt to achieve traffic calming. However, instead of having a calming affect the speed bumps push traffic to other streets that do not have speed bumps. This occurs on all streets except those residential areas that normally experience very low traffic in the first place. Though this may in theory be a good way to reduce congestion, it simply shifts the congested areas to different street without breaking up the congested areas.
