[sumo-user] Question to overlap signal detectors

[lcc <lccycc123@xxxxxxxxx>]

Hi Sumo developers, happy Valentine's day!

I have a question about delay-based signal’s detector placement

Here I’m showing an intersection. The northbound has 1 lane fork into 2 lanes, one is thru-only and one is right-turn only. (red arrow pointed)

The signalized lanes (thru and right-only lanes) are shorter than delay-based detector’s default length, so the detector is extended to the preceding segment (the 1 lane segment), and overlap each other.

This causes a problem that, when there is a long line waiting for thru signal phase, the right-turn detector also detects cars waiting (in the overlapping area) and keeps the right-turn phase green for a long time, even when there is no westbound traffic. The screenshot shows this case.

I can think of a few solutions:

1. Manually config the detector length to be shorter. OK for one case but not scalable.

2. Change the auto-generated signal schedule so that the northbound right turn will not be shared with westbound left turns. For example: change the tlLayout to incoming

3. Change the detector placement code, so that if two detectors are overlapping on the same lane, only place one detector. Say, thru-detector have higher priority. This requires a code change and definitely will have corner cases.

4. Stop the detector if there is a lane merge. I saw that there is similar logic in actuated lights’ detector placement as well. This may not work well if the lane fork is very close to the stop line.

5. Change signal type to actuated. The actuated sensor seems to have no such problem (AFACT)

Do you have a suggestion? In practice and the real world, how will sensors be placed in this case?

Thanks very much and hope you have a great valentine's day!