Revisiting an old topic

Don't worry about it until you experience signal related problems.

The foil encased tunnels will only cause a problem if you want to send commands while the train is in the tunnel, maybe...maybe not.

Just ensure that you have good connections at track joints and the power and control equipment is connected to a three-wire receptacle with a ground.

1. The ground can be any shape, loops would have no effect.

2. Many times an overhead wire will handle multiple tracks, like in tunnels or lower levels on multi-level layouts.  There is no hard and fast rule.

3. The only issue he is the metal bridge or tunnel MUST NOT be connected to the track common (outside rails) as this will actually short the TMCC signal.

4. I don't know anyone that has tried this, so I can't say if it would be good or bad.  Personally, if you want to handle the tunnels, just run a single ground wire overhead, that is usually a very good location.

5. I never saw that statement about Legacy vs. the TMCC BASE1, but I doubt it has much validity.  The track signal characteristics are pretty much exactly the same, only the information carried on the carrier is expanded for Legacy.

tayloora:

I had a second level with multiple track on it. The track on the second level did indeed interfere with the TMCC signal for track below it to the point locos would stop and the front light would blink. This was the sign of TMCC signal interference from the track above. As Lionel has stated it is not a lack of signal but too much signal (signal from track above adding to the signal from the track below) thus confusing the locomotive.

Since I was using grass mats on the top level instead of using copper foil I used the standard aluminum foil ones buys at a supermarket to save money. I placed it underneath the grass mat and using a bolt and washers connected the foil to earth ground at one end only. It solved all my interference problems. I have been told some people who don't use grass mats have placed the foil between the homasote and plywood and this works also.

Joe

I was under the impression there is lots of agreement.

I have 4 levels with both Legacy and DCS. What worked for me was to place a wire between the plywood and homosote sig sagging from one edge to the other side with attach points on the edge every 12 inches or so.  I then connected the wire from each level and ran a single wire to the water pipe.  Other where I had a bridge and I taped into that level's wire and ran it under the track on the bridge, each level wire does not follow any track and just crosses back and forth on top of the plywood.  I am running DCS, Legacy, TMCC with ERR units without any Legacy/TMCC signal issues with between 3 and 4 trains per loop, 2 or 3 loops per level, and at least one Legacy train per loop.