Are There Intelligent Traffic Lights?

[dave50]

If a minor road is backed up with traffic and there is a junction with traffic lights going into a main road which is not very busy, why dont the lights sense this and stay on green longer for the minor road to clear of traffic? This is typical of a junction I use a lot and this seems to happen regularly. 

[Ellipsis]

Yes ...

https://www.government-transformation.com/en/citizen-experience/smart-traffic-signals-50m-funding-boost-for-englands-roads

[barry1010]

We've had intelligent lights for many years, the sort that change to green when you approach on a not very busy minor road. Keeps the traffic flowing on the major road and only changes when necessary

[Old_Geezer]

The ones down the road to me seem "smart".  With nothing coming it the other direction and it green for you it gives the appearance of noting your approach and si deliberately changing to red.  Then when you are close enough to be braking, it may, sometimes, decide it'll go back to 'go' for you.

[Old_Geezer]

...so...

[Hymie]

The problem with most sets of traffic lights is that they only have a limited number of induction pick-ups (to detect approaching vehicles) in each direction.  Once all induction picks-up have detected a vehicle, there is no way the system can determine how much longer the traffic queue is in that direction; this is made worse by the series of induction pick-ups normally being placed less than 30m from the junction.

 

Imagine that you are trying to efficiently control a set of traffic lights, but all the information you have is the position and number of vehicles within a 30m approach in each direction.

[Toorak]

We have a set that during quiet times (overnight) become Green if you approach and there is no traffic on the main road.