Most Brooklyn-bound straphangers who travel over the Manhattan Bridge are familiar with the moment that the sweeping East River view is replaced by the darkness of a tunnel as the train descends back underground and, almost like clockwork, stops and holds in the tunnel before entering DeKalb station.
The delay happens often enough is more noteworthy when it doesn’t — and the MTA’s planners, signal officers and train crews all know that travel on the B, D, N, Q and R trains slows down through the series of switches and tracks known as the DeKalb interlocking.
But now, armed with new train cars, new signal systems — and, hopefully, billions of dollars with which to buy more of both — the MTA says relief is on the horizon for one of the subway systems most stubborn sections.
“Not everyone knows its name, but every Brooklyn rider knows the effects of the DeKalb interlocking,” Jamie Torres-Springer, MTA’s construction and development boss, said during a recent visit to DeKalb. “You’ve got 350,000 daily riders on these five lines, and almost every one of them seems to experience a few seconds or more of delay as one train is stuck on the bridge or in the tunnel, waiting for another train to cross in front of it.”
Put simply, the array of switches around the DeKalb Ave. station swaps trains between Manhattan’s Sixth Avenue line — the orange B and the D trains on a typical subway map— and Broadway Line — the yellow-bulleted N, Q and R — and recombines them to put the D train with the N and the R down Fourth Avenue in Brooklyn, and the B with the Q along Brooklyn’s Brighton Line.
This practice, called interlining, gives passengers the ability to get to more parts of the city without transferring trains. But it also means transit workers must act like air traffic controllers, governing the switches and signals that make some trains stop so that others can cross in front of them.
At DeKalb, this is done at the DeKalb Signal Tower — a room which, despite its lofty name, is buried behind a locked, non-descript door off the station’s mezzanine.
“This is essentially the beating heart of the B-division — the lettered lines,” said Chris Pangilinan, Chief of Operations and Planning for New York City Transit. “Almost all the lettered lines are affected somehow, either directly or indirectly, by all the lines running through here.”
At the center of the room sits the “model board,” a large black metal triptych with white lines showing tracks, switches and stations under the tower’s control. Small LED segments light up to show when a train has occupied a given section of track.
Perched atop the model board, amid memos from headquarters, sat a small wooden ship and a sign that read, “be grateful.”
The tower operators sitting at the board pressed buttons along the track lines, setting routes through the interlocking for oncoming subways as radio chatter crackled from their crews.
One door down, in a large relay room, rows and rows of 1930s era electro-mechanical relays clicked and clacked as tower operators set routes and trains moved along the tracks below.
“This is a large tower,” said Shanna Parker, a general superintendent with NYC Transit. “It has the B, the D, the Q, N [and] R regularly, the W certain times — in the morning and in the evenings you have Ws come through here — and the Franklin Ave. Shuttle.”
“You have DeKalb interlocking, you have Gold Street interlocking, Pacific Street interlocking, and you have Prospect Park interlocking, all in this tower,” she added.
As she spoke, lights on the board began to move, shadowing a train moving out from DeKalb and toward Atlantic Avenue.
But the lights don’t track the train as much as they identify occupied blocks of track, explained Sandy Castillo, an Assistant Chief Signals Officer for the subway system.
“The position is not accurate,” he said. “As you can see here, between DeKalb and Atlantic — which is about half a mile — you only have a set number of indications. The blocks that we detect, it’s a large area.”
That system, known as “block signaling,” only tells the tower operators roughly where a train is located. That can lead to traffic jams entering the interlocking.
“They’re very large physical blocks — the trains must be very far apart,” Castillo said. “And that adds to the time until you can replace a train in the station.”
By contrast, modern computerized signaling — known as communication-based train control, or CBTC — involves wireless transponders in a train communicating with transponders along the track, allowing for precise triangulation of a train’s location.
“With CBTC we can bring a train much closer,” said Castillo. “We know exactly where that train is. Timing is improved.”
CBTC — which requires new train cars as well as new signalling equipment — is already in use along the 7 and L trains, a portion of the E train on the Queens Boulevard Line, and was recently put into service on the the Culver line of the F train between West 8th St. and Ditmas Ave. in Brooklyn.
CBTC prep work has also been completed along the northern end of the A train, as well as the Crosstown Line of the G train.
The MTA had planned to install CBTC equipment along one of the two lines feeding the DeKalb Interlocking — the Sixth Avenue line of the B, D, F and M trains — in the 2020-2024 capital budget, but had been unable to fund the project amid delays to the state’s congestion tolling program.
Now that the toll is expected to start in 2025, Torres-Springer said the signal upgrades are back on track for Sixth Avenue. Upgrades to the Broadway line — the N, Q, R and W — are expected to be funded in the upcoming 2025-2029 capital budget.
In all, the MTA is asking for $5.4 billion to upgrade signals in the next five years, a budget that also includes CBTC installation on the J and the Z in Manhattan and the A and Rockaway Shuttle in southeastern Queens.
Not only would new signals speed trains up through the DeKalb Interlocking, it would also make the tower obsolete, allowing the interlocking to be controlled from afar at MTA’s Rail Control Center in Midtown Manhattan.
But there’s no firm timeline yet as to when DeKalb can be fully converted — with new equipment, signals and trains — to a modern CBTC system.
For now, those riders waiting to pass through the interlocking will have to sit tight, and hope the train gets held on the bridge where they can still enjoy the view.
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