Perhaps not specifically about technology but a tip to help keep your wits about you when driving in tunnels containing electronic signage.
One presumption that I work with when driving through these types of tunnels such as the Lane Cove Tunnel in Sydney or the Burnley Tunnel in Melbourne is that there is always the possibility of a speed camera in the vicinity. In tunnels, camera operators will attempt to include the currently allowed speed limit displayed on the overhead signage to use as evidence should it be required. When a reduced speed limit and those flashing yellow lights around the signed speed you really do need to make sure you are under the limit in order to avoid getting snapped.
Another method I use to determine where fixed speed cameras are located is by looking at the road underneath the electronic signage. If you can see what looks like a set of two rectangles cut into each lane then it probably could be sensors for a speed camera. Speed cameras work by determining how quickly a vehicle passes over these sensors and converting that into a speed.
Of course, you should always drive at a safe and legal speed no matter where you are but anything you can do to avoid a lapse in concentration costing you money and demerit points can only be a good thing.