Got it, thanks Dick. Google Maps has a decent satellite view of the roundhouse and turntable.
Finch;
There was a time you could drive down the access road from Bartlett st. (via Ricci supply's parking lot) to Maplewood Ave, but there are gates now, one behind Ricci, and one at the other end, just beyond Granite State minerals "other" yard, as you come in from Maplewood. The railroad shop building was occupied last time I checked, a marine construction company I think.