Photo by bankbryan on Flickr.

The American Legion Memorial Bridge helped usher in an era of suburban growth for Montgomery and Fairfax counties, which combined have over 2 million residents and 1.1 million jobs. As both counties have grown, the bridge remains the only link between them, and one almost exclusively dependent on single-occupancy vehicles.

The George Mason University Center for Regional Analysis (CRA) recently completed a study, Beyond the Legion Bridge, with recommendations on how to improve connections and offer more transportation options between Montgomery and Fairfax counties.

Today, there aren’t any HOV or express lanes across the bridge, nor is there any direct transit service. Meanwhile, traffic on the bridge continues to grow as almost all travel demand between the counties flows across the bridge as motor vehicle traffic.

Population & Employment Growth, 1960-2010

Traffic Counts 1965-2040

Why is traffic getting worse? CRA found that while the number of daily commuters between Montgomery and Fairfax has fallen over the past 20 years, the number of long-distance commuters going to or from outer suburban counties like Frederick, Loudoun or Prince William has increased, creating more traffic on the bridge. Meanwhile, 37% of trips over the Legion Bridge come from through-travelers or heavy trucks, adding to the burden placed on the bridge by commuters.

In 2009, Maryland and Virginia’s departments of transportation studied a 14-mile segment of I-495 and I-270 between Tysons Corner and Gaithersburg. They looked at a variety of potential changes, including restriping the highway to create more lanes, creating reversible lanes, or widening the bridge altogether.

The study found that minor improvements would not have much impact and even massive projects with price tags as high as $2.65 billion would only have modest impacts on congestion.  Clearly, no amount of money or engineering expertise applied to moving more vehicles over the bridge will solve the congestion problem.

Small fixes could create some breathing room

Given these challenges, what can leaders in Maryland and Virginia do? In the short term, I suggest three relatively simple strategies to mitigate the negative effects that traffic congestion has on the economy and quality of life.

  • Reduce demand for trips during peak period: For starters, we need to reduce the number of vehicle trips during rush hour. In the short term, we can do this by encouraging carpooling, vanpooling, transit use, alternative work hours, and telecommuting. These strategies will help the growing number of commuters who essentially have no existing option but to use the Legion Bridge and its congested feeder routes. This requires a coordinated effort from both states.
  • Provide alternatives for heavy trucks: Though heavy trucks make up just a small share of trips over the Legion Bridge, they have substantial impacts on its effectiveness. Since neither county has much of a manufacturing or warehousing base, most goods traveling on the bridge are either passing through or are going to retailers in each county. We should find potential alternate routes or bypasses for through trucks, while taking a look at how goods headed to each county get there.
  • Limit unnecessary bridge traffic: Some commuters who live in Montgomery County use the bridge only to reach the George Washington Parkway on their way to the District or Arlington. Low-cost solutions such as transit incentives, commuter buses or vanpools could give them an alternative. Meanwhile, more could be done to discourage through-traffic from outside the region from using the Legion Bridge, especially during the afternoon rush hour.

Long-term, a big fix is transit

While these interventions would relieve some pressure on the Legion Bridge, their benefits pale in comparison to those of a direct, high-capacity transit connection between Montgomery and Fairfax counties, specifically between Bethesda and Tysons Corner. They are already two of the largest employment and commerce hubs in the region, and plans for both areas direct future growth around their Metrorail stations.

Though they’re only seven miles apart, it’s hard to travel between them on transit. A Metrobus route ran from Bethesda to Tysons Corner from 1998 to 2003, but failed because there wasn’t a dedicated lane to make it more reliable.

Even after the Silver Line opens, a Metro trip between Bethesda and Tysons will take about an hour via Metro Center. A direct transit link, whether heavy rail, light rail, or express bus, would provide a faster and more efficient connection.

Political and business leaders on both sides of the Potomac have shown a willingness to think big and make necessary investments in road and transit infrastructure. Both Montgomery and Fairfax counties are also working to reduce car trips by building transit lines, like the Purple Line, Corridor Cities Transitway, and the Silver Line.

Option 1: Extend the Purple Line

Where would a new line go? One option would be to extend the Purple Line from its planned terminus in downtown Bethesda to either the future McLean or Tysons Corner Silver Line stations or the existing Dunn Loring Metro station. This 8-mile route could have additional stops at commercial nodes along the way, like Kenwood and Sumner in Maryland, and Langley and McLean Village in Virginia.

The public already owns much of the necessary right-of-way for this route. In Maryland, the line could run along Little Falls Parkway and the Capital Crescent Trail, while in Virginia, it could use Route 123. However, there would have to be a new bridge over or tunnel under the Potomac River somewhere south of Little Falls Dam, which could be very expensive.

Option 2: Use I-495

Another option could be to add a transitway along the Capital Beltway between Grosvenor and Tysons Corner. This could be an express bus route, which could predictably make the 12-mile trip in about 15 minutes, compared to over an hour under current rush hour conditions. Or it could be a heavy rail line, which would boost capacity, allow for additional stops, or even offer a one-seat ride between Shady Grove and Dulles Airport.

Other than the cost, this option’s biggest shortcoming is that it doesn’t make a direct connection between Bethesda and Tysons Corner. A third option would be to build both routes, though this would obviously be even more expensive.

What about the Techway?

Soon after the Legion Bridge opened, Maryland and Virginia began discussing another highway connection over the Potomac River. Called the Techway by supporters or the Zombie Outer Beltway by opponents, the project has had many fits and starts over the years.

At the moment, neither state has any serious plans to build it, though some officials and advocacy groups have kept the plan alive.

Even if a new crossing were built, history and academic research suggest that new highway infrastructure does not remove congestion from existing roads. Instead, new highways tend to stimulate additional residential and commercial development which, in turn, increases the overall volume of traffic in a given area. The highway still might get built one day, but if so, its presence would still not likely address the demand along the Legion Bridge corridor.

Looking ahead, Montgomery and Fairfax counties need better connectivity to protect the economy, public services, and quality of life that both counties have spent decades building.  Achieving this goal will require both a unified vision from political and business leaders in both Maryland and Virginia, and a long-term commitment to investing in the necessary improvements.