Abstract
An investigation is made of means by which vehicle speeds can be reduced in housing areas by designed irregularities in the road surface. The method ultimately developed for the described area was a system of imposing on the vehicle a vibration of 10-12 Hertz at speeds above the desired limit. This vibration, in the range of resonant frequency for most vehicles, is developed mainly in the suspension and mountings and is sufficient to make driving uncomfortable. In theory to restrict speeds to 25 kph a sinusoidal wave form in the surface with a wavelength of 600 mm should be adequate.