Thanks, Tom and Lew. It was a fun day. Let me add one caveat about the bridge: vibrations from heavy vehicles. Just when the pic is composed and a train is approaching, a truck may rumble past and the bridge heave.
A couple more pix from the day, and a bit more rambling. The next frame after this one, less than a second later, the lower head had changed (dropped?) to red. The dwarf signals are really bright.
Train departing the station - I think it was empty, after discharging passengers at the end of the run from New York.
After I'd been on the bridge a while, thought about investigating a business/light industrial area on the opposite side from where I'd walked onto the bridge's sidewalk, that appeared to have access to the right of way. Never got there - saw a train leaving the station from what, in the distance, appeared to be the easternmost track. Then it disappeared. Thirty seconds or a minute later, I hear the thrum of the diesel, but I still don't see a train.
Then it noses into view, mostly behind some trees, except for a clearing, on a solitary track east of the main, on the other side of the road I'd walked along to get to the bridge, and higher. Much later, finally figure out it must have been the Boston section of the Lake Shore Limited. On the walk back to the station, saw where that track diverges - open shot, but the light would be on the wrong side in the afternoon.
David