View of Rosslyn skyline. (Jeffrey MacMillan/For The Washington Post)

At 390 feet, the nearly complete office building in Rosslyn will be the tallest in the Washington region, pitched to potential tenants as the pinnacle of design, efficiency and, above all, accessibility.

Soaring over the Rosslyn Metro Station, 1812 North Moore Street is “conveniently located only two minutes by Metro from downtown Washington, D.C.,” according to the project’s marketing material.

The problem is when you look underneath. The 580,000-square-foot tower is sitting atop one of the region’s most congested stations.

The tunnel that connects the Rosslyn Metro station to the District under the Potomac River is the biggest choke point in the 37-year-old transit system, the site of its largest undergound traffic jam. Even when Metro is running the maximum number of trains possible, which is 26 per hour in each direction, riders at rush hour are often left to decide between cramming themselves onto an already stuffed train or waiting for the next one and hoping it isn’t as full. The advertised two-minute travel time to Foggy Bottom — which Metro’s trip planner say is actually three minutes — can quickly double or triple.

And that’s before the Silver Line arrives. When the five new stations in Fairfax County are added, 10 Silver Line trains will come in each direction through Rosslyn during rush hour, along with 11 Orange Line trains and just five Blue Line trains.

Since the recession, real estate developers have been gobbling up Metro-accessible land and planning and building offices and apartments from Reston to New Carrollton. More than 12,000 new apartments became available in 2012 and a similar number will arrive this year, 3,000 units more than the previous high.

This building renaissance will add thousands of new riders to the Metro system’s already overwhelmed tracks. Stemming the overflow may require not just changes to the system but to how the region makes land use decisions.

When 1812 North Moore Street is fully occupied, it likely will bring some 3,000 workers into the center of Rosslyn. The developer, Monday Properties, says it is committed to helping Metro expand and improve access. “We champion public transportation, as it is an essential component of our long-term Rosslyn redevelopment plan,” Tim Helmig, Monday executive vice president, said in an e-mail.

Monday Properties isn’t alone in betting on Rosslyn and preparing to send more people to the mobbed platform underground. Millions of square feet of new office space, apartments and hotels are in the works for the surrounding blocks. Down the street, the 521,000-square-foot Central Place project, planned by the JBG Cos. and approved by Arlington County, is promoted as “Towering high above the Rosslyn Metro station — and the competition.”

Concentrated development

Once the recession hit and the housing market went bust, some of the most viable places for local developers to build have been in core Washington neighborhoods with transit access. The difference remains startling. Of the 5.5 million square feet of office space under construction in the region, about 4.6 million of it, or 84 percent isn’t just near a Metro station but within a quarter mile of one, according to data from Jones Lang LaSalle, CoStar Group and Delta Associates.

In the District, that includes four buildings in the East End, two downtown and two in NoMa, the neighborhood behind Union Station. In Northern Virginia, there are three buildings being built in the Rosslyn-Ballston corridor, three near Silver Line stations in Tysons Corner and one near the Eisenhower Avenue station in Alexandria. In suburban Maryland, there is a 230,000-square-foot building being built near the Bethesda station by Carr Properties.

There is relatively little office construction taking place, however, at non-Metro-accessible locations. With few government agencies, contractors or other companies expanding, projects near Metro stations have a built-in advantage in landing the few available leases, according to Sandy Paul, executive vice president at Delta Associates.

“Owners are looking for ways for their buildings to stand out,” said Paul. “One of the things that you cannot replicate is proximity to Metro or public transit. You can create an interesting place, you can put restaurants or other stores in your project, but there are a limited number of Metro stations.”

There are also at least 25 major apartment projects within close proximity of Metro stations, according to Delta Associates, in a half dozen District neighborhoods, Bethesda, White Flint, Arlington, Alexandria, Tysons Corner and elsewhere. In all, according to Metro, 28 percent of the region’s real estate value is within a half-mile of Metro stations, even though that property constitutes only 4 percent of the land area. Not surprisingly, the most popular stations for residents to live and work are on the Metro Lines that are now most congested and in need of relief.

All 12 of the most overcrowded stations — those in need of new pedestrian connections, additional fare gates, wider mezzanines and wider platforms — are on the Red and Orange lines. Of the five that Metro says are in most dire need of relief — Farragut North, Farragut West, Gallery Place, Metro Center and Union Station — four have Red Line access and two have Orange Line access.

Upgrading Metro

In coming years, it may not be just the Red, Blue and Orange lines that will be under duress, but parts of the Green Line, because even though much of it wasn’t built until the 1990s many of its stations have become wildly popular locations for apartment renters.

In 2012, a study commissioned by the Capitol Riverfront Business Improvement District, a group funded by commercial property owners in the area around Nationals Park, predicted that over the next 20 years a string of 10 Green Line stations stretching from Petworth to the Navy Yard would create demand for 8,100 housing units, 4.3 million square feet of office space and 400,000 square feet of retail. It projected the addition of 19,000 jobs.

Metro has unveiled $6 billion worth of improvements it says are needed by 2025, among them increasing trains from six to eight cars ($2 billion), redesigning track connections or adding a new station in Rosslyn ($1 billion) and adding pedestrian tunnels connecting Metro Center to Gallery Place and Farragut North to Farragut West ($1 billion).

Shyam Kannan, director of planning for Metro, said that the rush to be near stations demonstrated the value the transit service, for all its shortfalls, is providing.

“All of those things, that’s good,” he said. “The concern we have now is the system is kind of busting at the seams. Anyone who has been in Metro Center or Gallery Place or L’Enfant or the Blue Line knows that we are getting really, really crowded.”

The challenge for Kannan, who wrote the Green Line study before joining the agency, is demonstrating the economic value created by transit to stakeholders that are in a position to pay for the improvements.

He said that value is obvious in NoMa, where a new Red Line station was added through a public-private partnership in 2004. Three years before the station opened, Kannan says the assessed value of real estate in the 35 surrounding blocks was $535 million. Three years after the opening, in 2007, it was $2.3 billion — a 330 percent increase.

“We’ve gone from location, location, location to access, access, access,” he said. “When you provide mobility you increase productivity and that’s what today’s office sector needs.”

Under-utilized stations

Regional stakeholders recognize that Metro’s needs stretch well beyond chronically lacking repairs for escalators, ceiling panels and lighting.

Getting Metro back into good operating shape “is probably the single most important thing for us to be doing,” said Ron Kirby, director of transportation planning at the Metropolitan Washington Council of Governments. “Everybody, I think, realizes that we have such an investment in this system that we have to be prepared to have it up and operating efficiently.”

Kirby said that some of the solutions to the overcrowding don’t require changes to the Metro system but to the way the region’s land is used. He gave two examples: First, Kirby argued that Metro and local governments need to continue to develop job centers near suburban Metro stations that will be accessible to people living in the core. Prince George’s County has 15 stations, more than any other jurisdiction, but few have major job centers nearby and many are adorned with nothing but parking lots. That causes Metro to run largely empty trains to those stations in the mornings and back from them in the evenings.

The unfilled trains are why Metro is facilitating an effort to attract the FBI headquarters to Greenbelt and another federal agency to Branch Avenue. “One of the things we’re very focused on is trying to take advantage of all the empty seats that we are running,” Kirby said.

Kirby said a second solution will be adding mixed-use neighborhoods near closer-in stations, such as Crystal City, so the agency “can sell the same seat twice,” by serving a commuter from Springfield to Crystal City and afterward another commuter from Crystal City to the District.

That requires Metro, local governments and the private sector coordinating their visions, but it’s far cheaper than adding new lines or stations: “A lot of what we need to do with the Metrorail challenge is shape the demand.”