Distribution of intensity for road traffic light signals

In this paper the requirements for the distribution of intensity of a red road traffic signal are discussed. Effective signal range of signals is calculated using data obtained from a series of investigations carried out with the financial assistance of the Australian Road Research Board. These calculations assume a typical relative intensity distribution and are for signals of various peak intensities. It is concluded that a red signal with a peak intensity of 200 cd would afford a good signal under most conditions and that one of 100 cd peak intensity might be considered adequate (a).