Final answer:
Speed bumps effectively slow down traffic by forcing vehicles to reduce speed due to their physical structure, complementing other measures such as traffic signals and emergency runaway ramps for improved road safety.
Step-by-step explanation:
Speed bumps are raised areas designed to slow down traffic as a measure to improve safety. When vehicles encounter a speed bump, they are forced to reduce their speed to safely cross the elevated structure, thereby reducing the likelihood they will speed through the intersection without regard to the posted speed limit. This is in contrast to a traffic signal, which also forces vehicles to slow down but relies on drivers' compliance with the signal rather than a physical change in the road to control speed.
A traffic signal can reduce the frequency of accidents because it prompts vehicles to stop and allows for controlled turns and pedestrian crossings, potentially lowering the number of accidents occurring at an intersection. However, speed bumps are effective at ensuring continuous slow speeds, even outside signal-controlled intersections. Their constant physical presence requires drivers to maintain slow speeds at all times, not just when a light is red.
In emergency situations, such as with semis that have experienced brake failure, other measures such as ramps of loose gravel along highways, like those in the Appalachians, serve as additional means to bring vehicles safely to a stop, highlighting that different traffic calming measures can be effective in different scenarios.