Every day dozens of Metro trains crisscross the region. How many cars does normal weekday service require? And where do those cars run? We asked the agency, and they were happy to provide the numbers.

Metro currently needs 860 cars to run normal service during rush hours. These cars make up 129 peak period trains.

The percentage of cars assigned to each line. The light gray area represents the cars not needed each day (spares).

The Red Line requires the most cars. At peak, it uses 288 cars in 41 trains. The Orange Line is in second place, with 204 cars on 30 trains. And in third place is the Green Line, whose 140 cars make up 20 trains.

The Blue Line falls fourth, with 138 cars making up 23 trains. The shortest line, the Yellow, requires 60 cars in just 10 trains.

In addition to the 124 trains assigned to a line, Metro positions 5 “gap trains” around the system that can be used to fill in when a train is taken out of service. These 5 trains require 30 cars.

Train length

During rush hours, the Red, Orange, and Green Lines operate with some 8-car trains, with the rest 6-cars long. The Blue and Yellow Lines use all 6-car trains.

Of the Red Line’s 41 trains used during rush hours, 21 (51%) are 8-car sets. On the Orange Line, 12 of the 30 trains (40%) are 8-cars long. The Green Line uses 10 8-car trains out of 20 total trains (50%).

Systemwide, Metro operates 43 8-car trains and 86 6-car trains during peak hours. That means that one-third of trains run with full-length consists.


Metro doesn’t need as many trains or as many cars during off-peak periods.

The Red Line requires 21 trains and 126 cars. There are 12 trains and 72 cars on the Blue Line. While the Orange needs 66 cars in 11 trains. For the Green, it’s 10 trains and 60 cars, and on the Yellow, it’s 8 trains and 48 cars.

Rush Plus

On June 18, Metro will start new rail service patterns. In addition to the 5 colored lines, 2 new services will be starting. One will run between Vienna and Largo Town Center (to be colored orange). The other will run between Franconia-Springfield and Greenbelt (colored yellow).

The Franconia to Greenbelt service will not require any additional trains, since 3 trains per hour that currently run as Blue Line trains are being shifted to the Yellow Line bridge. But the new Vienna-Largo service will require Metro to add several trains during peak hours.

While WMATA did not respond to requests for how many new trains it will require for Rush Plus, the 58 minute Vienna-Largo run time and 20 minute headway could be done with 6 trains.

Metro also did not provide data about how many cars this will require. If all 6 of the new trains are 6-car trains, it will add 36 cars to Metro’s peak vehicle requirement. If all 6 of the new trains are 8-car trains, it will mean adding 48 cars during rush hours.

That would increase the size of the peak vehicle requirement to between 896 and 908 cars.

Fleet size

Metro has 1,104 cars that are in its active fleet. But the agency can’t schedule all of those cars on any given day.

Metro aims to have a spare ratio of 20%, to account for trains that are out of service for repair or preventative maintenance. In the 1980s, as system expansion outpaced new rolling stock acquisition, Metro allowed its spare ratio to drop and that led to a corresponding drop in reliability.

What this means is that if the system has a peak vehicle requirement of 896 cars, it needs to have an additional 179 cars (20% of 896) set aside as spares. If the system has a peak vehicle requirement of 908 cars, it needs to have an additional 182 cars as spares — a total of 1,090 cars. Metro’s fleet today is 1,104 cars, so as long as no major repair issue forces them to take a lot of cars out of service for a long period, they should have enough.

Tagged: metro, transit, wmata

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Matt Johnson has lived in the Washington area since 2007. He has a Master’s in Planning from the University of Maryland and a BS in Public Policy from Georgia Tech. He lives in Dupont Circle. He’s a member of the American Institute of Certified Planners, and is an employee of the Montgomery County Department of Transportation. His views are his own and do not represent those of his employer.