Study of clearance interval at traffic signals. Paper presented at the 47th Highway Research Board (HRB) Congress, Washington, D.C., January 1968.

It should be emphasized that the purpose of this pilot investigation was to identify promising modifications of amber period, duration, transverse pavement markings, and supplemental advanced signing which gave evidence of improvements of safe operations at signalised intersections. The purpose of this pilot investigation was not to provide conclusive evidence for the modifications studied. A comprehensive summary tabulation of the two sets of risk measurements for each of the ten cells of data is shown.