If the tunnels are anyhting like ones I tried to make using my Paris Metro track (third outside rail) you will probably find that one of the two tracks ends up with the conductor rails in the wrong place. It is in the nature of tunnel tracks, which are placed to left and right of centre in the config file (ie. plus and minus values) that both are placed the same way round.
I had to solve this by making two half-tunnels - but perhaps I'm a bit fussy!
Ray
