How is the quality of traffic flow on a roadway with traffic signals measured?
The first measure of quality of traffic flow is the level of service of the roadway itself, which reflects how traffic would flow in the absence of traffic signals. It measures the percentage of time spent traveling below the posted speed limit. In areas where traffic signals are installed, they tend to control traffic flow in their immediate vicinity. In those areas a second measure is used. It is based upon the delays a motorist may expect to encounter traveling through the signalized intersection. This measure is based upon the amount of total delay, which includes stopped time and time spent slowing down and speeding up from a red signal indication.
