Along the Metro tracks just south of Pentagon station, there are two dead-end tunnels that branch off in the direction of Columbia Pike. They were built so Metro could expand westward in the future, so why has the line never received serious consideration?

These Metro corridors got heavy consideration in the 1960s. Graphic by the author.

Columbia Pike, which runs southwest from the Pentagon to Annandale, passes through several residential and commercial areas, including Bailey’s Crossroads at the intersection with Leesburg Pike. When Metro was in its initial planning stages in the 1960s, the Northern Virginia Transportation Commission and the National Capital Transportation Agency studied routes on the Virginia side of the Potomac, and Columbia Pike was among the routes the agencies considered.

The NVTC envisioned a Columbia Pike Metro line running to Americana Fairfax at the Beltway via Little River Turnpike, which is where Columbia Pike ends in Annandale. The NCTA considered a route along Columbia Pike that was as an alternative to what would become the Orange Line. It ran from the Pentagon to the Barcroft neighborhood, where it turned north at Four Mile Run until it joined I-66 and continued west.

Ultimately, a number of factors led to this corridor being dropped from consideration, the largest being its price tag. To avoid tunneling and to minimize cost, Metro planners prioritized using existing rights-of-way, such as highway medians and railroads, for its potential routes.

This, combined with the desire to ensure Metro connectivity to north Arlington and Springfield, led to the Virginia getting Metro corridors along I-66 and the RF&P railroad (what would become the Orange and Blue lines, respectively).

Metro tunnels outside of the Pentagon. Graphic by the author.

The Columbia Pike line would have needed to be entirely in a tunnel all the way to Annandale, and its projected ridership was simply not sufficient to justify such a high cost. The cost also resulted in pressure from Maryland to prevent Virginia from having three lines, worried that the Columbia Pike line would reduce money available for the rest of the system.

There were some outspoken proponents of a Columbia Pike line, most notably the chairman of the Fairfax County Board of Supervisors, Frederick Babson. Babson had campaigned on getting the Columbia Pike line built, and as such was very vocal at planning meetings.

In 1967, largely to placate Babson, WMATA did some informal studies on the Columbia Pike line as an alternative to the north Arlington line. These studies did not change the Board’s decision, and to this day remain the last studies done on a Columbia Pike Metro line.

Likely as a consolation, the Columbia Pike line remained on WMATA’s planning maps as part of several aspirational dotted lines for “future extensions.” The corridor described by the NVTC appears on this 1967 proposed network with a modification to serve Lincolnia, but by the time the official Adopted Regional System was determined, the line was truncated there.

The Columbia Pike line on the 1968 Adopted Regional System. Image from DDOT.

In 1968, WMATA Board director Jay Ricks noted that the Columbia Pike line was ruled out with the understanding that it would have top priority for any future extensions, and that the line would be reinstated if the state of Virginia made more money available.

The Silver Line opened in 2014, so this obviously didn’t happen. A Columbia Pike line has not seen any serious consideration since 1967. The Columbia Pike Transit Initiative did not include rapid transit as a possible alternative, and though WMATA has recently studied many theoretical routes as part of its long-term vision, a line along Columbia Pike is not one of them.

Is a Columbia Pike line possible in the future?

Though some residents along Columbia Pike were opposed to a Metro line because they didn’t want the level of development and growth that occurred in north Arlington, such development has occurred regardless. There is much more residential density along Columbia Pike than there used to be, and job centers like the Mark Center have popped up along the corridor. The Skyline Center at Bailey’s Crossroads was even built largely in anticipation of a Metro line.

Would this increase in potential ridership be enough to justify constructing the line today?

Bailey’s Crossroads skyline. Photo by Dan Malouff.

Unfortunately, the cost of an underground Metro line remains a substantial hurdle. The proposed tunneled segments of the Silver Line in Tysons and Dulles Airport were rejected due to their high cost. Given that Arlington County had difficulty justifying the cost of the Columbia Pike streetcar line, proposing an entirely tunneled Metro line may be a near-impossible task.

However, the most significant barrier to a Columbia Pike Metro line is capacity. How this line would integrate into the Metro system was never seriously considered. Simply building off of the stub tunnels at Pentagon would create the same capacity issue that planners are working to solve at Rosslyn, where there’s a huge bottleneck, and like most proposed Metro extensions, a new downtown core line would need to come before any regional expansion because all possible routes the line could take after Pentagon are at capacity.

Metro’s current capacity constraints. Graphic by Matt Johnson.

Metro’s current long-term vision for future service downtown includes a loop line via Georgetown and Union Station with a supplementary station at Rosslyn and the Pentagon. The addition of the second Pentagon station could allow for a Columbia Pike line to exist, integrating into the downtown loop. I’ve created a hypothetical example of how this might work below, utilizing the alignment from 1967.

How a Columbia Pike line could integrate into the future Metro system. Graphic by the author.

The growth of the Columbia Pike corridor has made it a desirable line for many residents in the area, but its high cost and operational difficulties mean that we won’t see such a line for many years, at least until Metro’s downtown core capacity issues are resolved first.