Delay at signal-controlled intersections

Abstract

As has been briefly mentioned in chapter 36, the delay to vehicles on a traffic-signal approach has been investigated by F. V. Webster and reported in Road Research Technical Paper 39. By a combination of queueing theory and digital computer simulation it has been shown that the average delay per vehicle on a particular intersection arm is given by $$ where d = average delay per vehicle,

c = cycle time,

λ = proportion of the cycle that is effectively green for the phase under consideration (that is, effective green time/cycle time),

q = flow,

s = saturation flow,

x = degree of saturation, which is the ratio of actual flow to the maximum flow that can be passed through the approach (that is ,q/λs).