I had a few hours to spare today, so I visited BLDG 92 at the Brooklyn Navy Yard. I had a great time — the exhibit is awesome, and I met some cool people. I had planned to write a post on the HMS Jersey and the other prisoner-ships that were moored in Wallabout Bay during the Revolutionary War, but that will have to wait. I got sidetracked by a project that has held my curiosity for a while.
All things considered, New York has a great subway system: it’s extensive, it runs 24 hours, and it has local and express trains on many lines. But there’s only one stop (that I’m aware of, anyway) that has local, express, and super-express trains. That stop is DeKalb Avenue on the BMT.
The station has six tracks, four of which are accessible from platforms. During the day on weekdays, the B and Q share the outside tracks; the R has the inside tracks to itself; and the D and N share the super-express tracks, which run inside the R in a walled-off area, although you can see into this area from the platform. Heading northbound from DeKalb Avenue, the R hits some local stops in Brooklyn before reaching Manhattan at Whitehall St, while the other four lines cross the Manhattan Bridge.
I ride the B and the Q regularly, but it was only recently I noticed that by the time you reach daylight on the bridge going toward Manhattan, all B and D trains — in both directions — are on the north side of the bridge, while all N and Q trains are on the south side. So they must do a massive switcheroo somewhere underground. But how? There’s no way the tracks cross, because that would be too dangerous. Naturally, this became an obsession of sorts. I drew this diagram as a starting-point to my investigation.
I had one clue as to where the cross-over might happen, and I’ll sum it up in one word: zoetrope. If you’re on the B or the Q heading toward Manhattan, 20-30 seconds after leaving the station, you’ll see what appears to be a movie playing on the right side of the train. It’s actually a succession of 228 hand-painted frames, installed in 1980 by filmmaker Bill Brand, called Masstransiscope. It’s not too much farther until you hit daylight, so the northbound B and the Q must split somewhere in that space.
As it turns out, Masstransiscope is on the platform of the abandoned Myrtle Av station, which last saw service in 1956. (The southbound platform no longer exists.) The station was closed to allow for an expansion of the DeKalb Av stop and the installation of “flying junctions”. Flying junctions ensure tracks never cross, allowing multiple trains to use the same area simultaneously without risk of collision.
I came across a map of the track layout in question on nycsubway.org, a great resource for anyone who loves the system:
So there’s our answer! Easy, right? I looked at it for ten minutes and still had no idea what was going on. (Imagine how brilliant the engineers who created this mess must have been.)
I’m a weird dude, so I decided to take it off the two-dimensional page and into the three-dimensional world. And what better day than a rainy one for a little arts-and-crafts action?
Enter: Play-Doh! Or, in this case, ALEX Super Soft Glitter Dough, because it was cheaper.
I figured I could get two lines out of each pack, splitting each in half and rolling them into a long tube. Turns out doing this is like riding a bicycle: you don’t forget it from when you were five.
It took a bit of spatial thinking, but I discovered the trick: the B and the D always go on top. Add some Pez to serve as bridges and you get the final result:
And from different angles, looking from the stop (left) and from the bridge:
So now I know. I’ll sleep well tonight.