Hello, this may be useful...
Although when on railway style right of way the signalling is traditional railway colour lights, when in street mode they use white dot / white bar signals.
For an interesting ride... Take the U5 or U6 from Charlottenburg in the city centre. Sit behind the driver (if you can) and watch the speedometer with the fluctuating needle on the dial which shows the maximum speed for the section of line, etc.
By the next stop (Olgaeck) you will be in open air. This stop is where the U15 diverges but for this experience stay on the U5 / U6. This is a very busy traffic junction and the light rail must slot in with everyone else, there at this junction the signal includes a countdown timer to encourage the LRV to be ready to depart asap when it receives a go signal.
In the image below the signal for the U15 is on the left and U5/U6 on the right
The A tells the driver that their request for a turn in the traffic signal phasing has been accepted.
The white bar is 'stop'
T04 is part of the 10 second coundown timer
The arrow shows the direction the points are set.
The journey away from the city centre on the U5 U6 includes some street tramway - basically there was not enough space for two separate traffic lanes per direction of travel and two segregated rail lines. To help improve safety there are traffic signals which stop the street traffic where the LRV joins the traffic lanes. I've seen it happen that in heavy evening rush hour traffic the queues mean that the LRV is delayed in the congestion.
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more to come... btw: in case anyone is wondering about copyright, I took these pics and they are online at my website
citytransport.info