  Over speeding is an important problem in Nigeria. The Nigerian Federal Road
Safety Commission report shows that over speeding is directly responsible for
over 50 percent of road crashes in the country. Speed bumps particularly on
highways have not proved to be the solution; they rather contribute more to the
problem. Based the advent of the dedicated short range communications (DSRC)
systems defined by the IEEE 802.11p standard, we proposed a radio frequency
based speed bump to mimic the operation of traditional speed breakers. The
model consists of a roadside unit and an in-vehicle unit that works with the
already installed speed limiter in vehicles. In our work, we showed that the RF
based model is able to decelerate the vehicle at a recommended rate of 10 m/s2
over a convenient stopping distance of 80 m. Our work also showed that signal
strength based adaptive speed limiter systems can be used as a reliable
substitute to GPS thus eradicating the need for additional hardware in the
design.
