It's funny, the first few days of heavy testing in both versions of this terrain, the trains and I could do damage to each other. That hasn't happened in weeks now and I've tried. I don't know why.
My script sets the trains' downtime to half default. Never timed it to check, but if it's working, that's 5 minutes. I also checked, I can't remove the gun cars. afaik I can't dial back the train guns without it changing the field ack too, so I won't do that. The trains were always a concern. Jaeger and I talked about it and both like leaving the trains in for different reasons. That may change of course.
Anyone running a room they watch over wouldn't need to use high ground act settings!
I'm running an unattended room, so having all the ground ack cranked up protects new player, and old, from getting vultched their first few up's. That's the biggest turn-off in my mind when going to any arena. Unless you love upping at a capped base in the MA for fast action like I did once upon a time.

I'd be interested to know if anyone can damage the trains. I can't, which defeats the purpose of having them.