superplum wrote:Tsk tsk!
The Amber to Red cycle should last min 2secs; Red+Amber to Green - min 3 secs. Reason, provides a small delay to allow traffic to clear (theoretically).
Where are you getting these figures from? Maybe they've been changed, last time I looked the Amber phase was 3s±0.25 and the Red/Amber phase was 2s±0.25 (irrespective of speed limit).
There can also be an additional delay (all red phase).
http://www.traffic-signal-design.com/te ... y_main.htm
The time between end of right of way for a phase and the start of the right of way for the next phase. These comprise of the 3s leaving amber for the phase losing right of way and the 2s starting red / amber for the phase gaining right of way. Depending on the geometry of the junction there may also be a period of all red to allow all traffic to clear the junction.
Intergreens must be measured carefully when configuring a junction as one that is too short can mean traffic from the previous stage is still clearing the junction when the next stage starts. Conversely, intergreens which are too long can lead to unnecessary delay within a junction which may have negative implications on the level of queuing and delay experienced at the junction."