I suppose most of these photos used a long exposure, and/or a rushing-by subway for "lighting". There seem to be some small lights for workers/emergency situations, but nothing compared to the lighting of an operational subway station.
It depends on the system.
Paris metro tunnels are constantly lit. It's less than station lighting, but more than enough that you don't need a lamp with you.
It's definitely an oddity, most systems are unlit (Barcelona has entrances lit then nothing, Ukraine, Russia, etc all unlit).
Interestingly, unlit tunnels bring the advantage of if you're seen, the lights are turned on, giving you a clear warning sign to leave.
In the Paris system, you need to actively count the delay between trains to ensure traffic isn't cut. We had one or two encounters where we realised that it had been 4 minutes between trains when they we running on 2 minute intervals..
Two minute intervals! My kingdom for a commute on two minute intervals. The very busiest lines get down to perhaps 6 trains an hour on peak, 3 normally.
Most of the world's busiest systems have at least a line or several which approaches 90 second intervals at peak hours. Moscow, Paris, London, even NYC (and I would have to assume many Asian systems I'm not as familiar with as well). 30-40 trains an hour is the gold standard, but obviously only makes sense if there is enough ridership.
What's the scenario there? They lengthen the headway on the whole line until they catch you or they actually cancel some trains? Why? I'm curious what the operational response is from their side.
Typically they will announce to the PCC (central control) that they sighted people in the tunnels. The next train that comes through the sector will roll at walking speed. If you haven't cleared out by that time and get seen, they stop all traffic on the line, and send in rail police from each side of the tunnel to find you.
