Is it a speed hump or a speed bump?

Speed bumps and speed humps are both useful in encouraging safe driving in pedestrian zones. Speed humps are useful in places where traffic needs to continuously flow, and speed bumps in smaller areas that pedestrians and vehicular traffic share space in equal amounts. Both speed bumps and speed humps offer greater flexibility than other more planning intensive physical traffic calming methods like roundabouts or one-way streets. They are modular and can be installed simply and inexpensively on most existing surfaces.