Which traffic calming measure would most likely reduce vehicle speeds?

Speed bumps are specifically designed to physically impede the progress of vehicles, requiring drivers to slow down significantly in order to navigate over them safely. This physical barrier reduces speed effectively, as the design of speed bumps necessitates that drivers reduce their speed to avoid discomfort or potential damage to their vehicles.

While roundabouts can also encourage reduced speeds by requiring drivers to yield and navigate through a circular intersection, they do not necessarily impose the same direct physical restrictions on vehicle speed as speed bumps do. Increased signage may provide drivers with information that advises them to drive at slower speeds, but it does not impose any physical consequences for not adhering to speed limits. Similarly, bus lanes are primarily designed to facilitate public transit and improve the reliability of bus services rather than to directly reduce vehicle speeds.