How long does an isolated block be?

Look into the Z-stuff.

They sell a dwarf signal that activates crossing

gates ect. They look nice and work quite well,

and you don't have to cut any track !

Set it down, test it out, if not happy it can easely

be moved....

It all depends on what you want the signal to do. In real life signals are there to protect oncoming trains from running into the back of other trains or cars that are parked on the track. If this is what you want then your block would be as long as the train or area you want to protect. If you just want something to give some action and don't care if the aspect is correct or not then the Z-stuff would be simpler. The trouble with z-stuff and similar items is that once the train leaves the detection area the signal will eventually clear and go back to green. Since you are protecting a tunnel, if you stop the train inside you will have no indication it is there.

Al

Based on what you have said John, I would recommend isolating an entire block for each track.  Therefore, from the time the locomotive enters the block (passes the first signal) and the last car leaves the block as it passes the second signal, the block will show being occupied.  As noted on an earlier thread I have used the relays from Scott's Odds and Ends with great success.  Regard,Bo   

You can visit my website Bo's Trains at http://www.bostrains.com