They have an automated system that triggers lights and if the driver understands the tannoy, is diverted into the holding slip to await punishment. If they don't follow instructions, the traffic is held until someone arrives.
It all used to be done by traffic officers before the divert lane was built and used to be a specific posting with very quick response times to minimise disruption. Progress, eh?
If they are getting stuck in the tunnels at Blackwall, it is through breakdown or running out of fuel…………..the up slopes move the remaining fuel to the back of tanks. Same with cars.
That is what I mean when I mentioned signals prior to entry.
I spent quite a few years working on the refurbishing scheme on that tunnel. We used to provide impact protection vehicles, when the tidal contra flow was in place, just before police stopped it, due to too many head on collisions.
You will be surprised, as to how many drivers do 'try it on', disregarding all the fail safe systems on the approach to the NB tunnel.
All you have to do, is to look at the height restrictor bars on the approach to the tunnel,as to how many are bent.
Admittedly,I have had not much to do with this tunnel since 2010, but back then brake downs and fuel wasn't even half to account for unauthorised tunnel entry.
Not sure what are the stats at the moment, as my input is from between 2005 to 2010.
Also, it was the tunnel control dealing with the minor emergencies not the police. They would only get involved when there was an actual incident, or uncooperative driver(s).