Reply to "my 8 x 13 design with 45-degree crossovers and mth arch bridge"

Where is the train stopping? In one spot every time?

Denatured alcohol on a piece of old bath towel or wash cloth with a little rubbing will help. Check the wheels, too. They get a crud buildup.

I use a drywall sanding pole with a swivel head and put the cloth on instead of sandpaper. 2-3 minutes to wipe your whole layout. You can even sneak it in the tunnel from each end.

Pole sander from HomeDepot