Work out traffic signal timing instantly with clear inputs, formula shown and shareable results.
Lost time is the amber plus all-red interval for every phase, and the effective green available is the cycle length less that lost time, divided between the phases. Lost time is fixed per phase, so a four phase junction on a short cycle can spend a third of every cycle with nobody moving, which is why cycle length and phase count are traded off.
Lost time
lost = phases x (amber + all red clearance)
Green per phase
green = (cycle length - lost time) / phases
lost = phases x (amber + all red clearance). Lost time is the amber plus all-red interval for every phase, and the effective green available is the cycle length less that lost time, divided between the phases.
Lost time is fixed per phase, so a four phase junction on a short cycle can spend a third of every cycle with nobody moving, which is why cycle length and phase count are traded off.
Enter cycle length, number of phases, amber time per phase, all red clearance per phase. The defaults shown are a realistic worked example — swap in your own figures to get a result you can use.