Metro's operations center currently commands the system from three desks. Soon, a fourth will run the Silver Line and part of the Orange Line. Image by Peter Dovak used with permission.

Like the control tower at the airport, Metro has control centers that tell trains where to go. Soon, Metro will make an addition that will spread out the workload and make the system safer and more reliable.

The Rail Operations Control Center (ROCC), the brain of Metro’s rail network, has three “desks,” each of which controls a different part of the system. On a normal day, Rail Traffic Controllers will talk with train operators a number of times. For example, the RTC may need to tell the operator to hold at stations if they’re too close to the train ahead (this is a “schedule adjustment” if you’ve heard that phrase before).

Or if there’s an interlocking problem where a switch stops working for whatever reason, the RTC may be giving the train operator permission to pass a red signal — something the operator never wants to do without proper permission — to get to the next station. Still other times during mid-day or in the evenings, the RTC will give the train operator permission to drop track workers off at a specific location on the tracks, if they need to go get some work done.

All these instructions from the RTCs come over the radio system, which keeps the ROCC in constant contact with all trains in the system. Each additional instruction — and required word-for-word readback by the train operator — is an additional radio transmission. And just like a typical radio, only one person or one station can be transmitting at a time. There’s a finite upper limit to how much each RTC can handle.

Here's what the ROCC's three desks currently handle

The OPS1 desk, as it’s called, runs the Red Line from Shady Grove to Glenmont. Once a train leaves either terminal, its operator will talk to the same pair of controllers at the ROCC all the way through to the other side of the line. If a train is taking the shorter route and only running from Grosvenor to Silver Spring, the operator contacts OPS1 when leaving those stations, and contacts a supervisor manning either terminal when approaching.

The OPS2 desk is the busiest in the system, according to the Federal Transit Administration. The pair of controllers responsible for running OPS2 manages the Orange and Silver Lines as well as part of the Blue Line. When trains arrive and berth northbound at Arlington Cemetery, they switch over to OPS2 in order to continue their trips to Largo. When berthing at Arlington Cemetery southbound, Blue line trains switch over to OPS3.

OPS3 takes the handoff from OPS2, and runs the Blue Line from the Arlington Cemetery southbound platform down to Franconia. OPS3 also runs the entirety of the Yellow and Green lines from Branch and Huntington to Greenbelt.

Splitting the system into these three makes running the trains fairly manageable. It would be impossible for a single pair of controllers to run all six lines— there’s just way too much going on.

It’s important for the controllers to be able to maintain situational awareness of what they’re in charge of control at all times, especially when there’s an incident on the line like a train malfunction, medical emergency, or track issue. They may have to devote additional attention to that incident, but there are still other trains that might need to move or be single-tracked in the meantime. They need to be able to manage their entire section while something is going on, and not let all other trains suffer during an incident.

Metro is adding a fourth desk to help split train control functions a bit more

WMATA photo of the (now-backup) Rail Operations Control Center. Image by WMATA used with permission.

With the addition of the Silver line in 2014, the OPS2 desk gained the workload of an additional five stations, with another six on the way when Phase II opens around 2020. The extra stations and use of manual train driving instead of computer-aided train driving means that this is the busiest desk in ROCC, having to manage the majority of three lines. So Metro is splitting the desk in two.

A new desk, OPS4, is set to be put into service this month. The additional pair of controllers running OPS4 will be responsible for the Silver Line and part of the Orange Line, although it hasn’t been decided where the split will be. The most logical place for the split is likely at Court House, so OPS2 no longer has to worry about Orange and Silver west of that location.

Cutting OPS2 at Court House would mean that when a Silver Line train arrives inbound at the station, the operator would switch over to OPS2 and continue their trip over to DC. When arriving outbound at the station, the operator would switch from OPS2 to OPS4 to continue to WIehle or Ashburn. Spitting here reduces the OPS2 workload by 12 stations, meaning they can better focus on everything east of Rosslyn.

The OPS4 desk will be responsible for those 12 stations from Court House and west today, increasing to 18 stations in 2020 with Silver Phase II. This compares with OPS1 which is responsible for 27 stations, and OPS3 which is responsible for 32 stations.

ROCC staff and the FTA have noted that controllers already have high work loads while dealing with trains, track inspections, requests to turn power on and off, and other maintenance activity. Adding a fourth desk helps to split these responsibilities out more to make communications smoother, and allow for quicker responses to train operators and any issues that might arise.