I walked through the bike- and pedestrian tunnel today - back and forth :-) 12000 steps on my clock so far....
There is a sundial in the middle of the tunnel. Inside the mountain. The spotlights are timed so they shine their light on the reflectors in the ceiling which in turn reflects the light down to the correct "time" on the floor. You can see the 10 is brighter than the other numbers and I was there at around 10 o'clock.
This tunnel is such an excellent well-thought-out use of space and this sundial is incredible. How clever! Wonderful place to walk.