Awesome -- this is helpful. Do you remember/are you able to lay your hands on the docs that detail this?They'd take the Fitchburg portal, with a new crossover installed outside. That gives access to the layover yard (and keep in mind the Fitchburg main is currently scheduled to be realigned south to add a couple more layover berths). Shop access would come from a reverse move inside the layover yard. Wye and fueling pad (for dual-mode locos) access would come from a crossover outside the Lowell/Eastern/Western portal. Expect some heavy reconfiguration of the SE corner inside-yard switch layout to square full access from the sharper angles of portal trajectories.