Abstract
In the evaluation of traffic control by traffic signals the journey time lost by different road users is next in importance to safety. Lost journey time is the additional journey time needed due to the hindrance of traffic signals. Next to safety and waiting time other factors which can be important in the evaluation are: capacity, traffic concentration, air pollution and energy conservation. This article is limited to the average waiting time at traffic signal controlled junctions. The lost time can be measured automatically and the traffic signals can be readjusted to optimise the traffic flow.