Abstract
The chronological development of the most commonly used intergreen interval formulas is traced and a disparity is disclosed between the interpretation presumed by ite and that originally proposed by gazis et al. A realistic example clearly shows that proper application of the speed-location diagram introduced by gazis et al. Can enhance the traffic engineer's judgment and can provide a consistent means of reporting research-related observations. The speed-location diagram of the intergreen interval problem must be adopted as a standard tool by traffic engineering practitioners and researchers. This paper appears in transportation research record no. 1324, Communications, traffic signals, and traffic control devices 1991