the idea given by JD is perfect .. but the idea by German company *****... i mean dial to switch on the light ... WTF ...
and also ... idea by JD is much simpler to implement .. really ....
I had thought of a similar idea long time back for red light crossings ... at different times .. different roads on a single red light crossing have different traffic frequency. Yet ... the light goes red on each crossing (4) for a fixed time. It happens that at say noon .. the road on which there is no traffic has red light for just 30 sec .. and the road that has a lot of traffic has red light for 60 sec ... and it happens entire noon causing jam at one road .. yet the other (perpendicular) one is just empty ...
So have a magnetic barrier around 500 metres off the red light junction and continuously monitor the traffic at each road (4 roads) and depending on the traffic rush of each road ... adjust the red light timings. The road that has max traffic .. let the red light turn on there only for 10-20 seconds and allow green there for longer durations.
Really ... loads of traffic jams can be avoided ...

....
Or ... build a Flyover .. ha ha ha ...