2. A traffic engineering study on traffic delay was conducted at intersections with signals on urban streets. Three types of traffic signals were utilized in the study: 1) pre-timed, 2) semi-actuated, and 3) fully-actuated. Five intersections were used for each type of signal. The measure of traffic delay used in the study was the average stopped time per vehicle at each of the intersections (seconds/vehicle). Additionally, they were interested in the following comparisons: 1) Is there a difference between pre-timed and actuated traffic signals in the seconds/vehicle. 2) Is there a difference between semi- and fully-actuated traffic signals in the seconds/vehicle Pre-timed Semi-actuated Fully-actuated 36.6 17.5 15.0 39.2 20.6 10.4 30.4 18.7 18.9 37.1 25.7 10.5 34.1 22.0 15.2