The last bridge built to span the Potomac River in the Washington region was the American Legion Memorial Bridge, part of the Capital Beltway, in 1962. The population of Montgomery and Fairfax counties, which the bridge connected, totaled about 600,000. In the intervening six decades, the combined populations now exceed 2.1 million, accounting for 36% of the region’s population and 44% of its personal income.
It would seem logical to promote connectivity between the two dominant jurisdictions in the Washington area, if only to facilitate mutually beneficial commerce. In 1992 the bridge was expanded from six to eight through lanes, but traffic has continued to grow since then, from 172,000 vehicles per day to 226,000. The Metropolitan Washington Council of Governments projects another 43,000 by 2040.
In a new paper, David E. Versel, senior research associate with George Mason University’s Center for Regional Analysis, evaluates alternatives for addressing the worsening congestion on the bridge. Along the way, he debunks a commonly held theory: that the disparity in job creation between Fairfax and Montgomery counties — Fairfax created roughly 130,000 more jobs between 1990 and 2010 — led to an increase in community from Montgomery to Fairfax. In fact, the number of people commuting between the two jurisdictions declined.
The best explanation for the increase in traffic, Versel says, is the growth in the number of commuters from “fringe” jurisdictions such as Loudoun and Prince William counties in Virginia and Frederick County, Md.
As for alternatives, widening the bridge and adding lanes would cost an estimated $1 billion to $2.65 billion. While those improvements would improve congestion at the bridge, several other segments of Interstate 495 would remain in system failure. Concludes Versel:
Any solution will need to involve the reduction of vehicle trips during peak periods. In the short term this can be accomplished by encouraging carpooling, vanpooling, transit use, alternative work hours, and telecommuting. In the long term it will require concentrating both residential and commercial development around transit and shared-ride facilities to ensure that more people can get to an from work without driving in single-occupancy vehicles. Though both counties are already aggressively pursuing such transit-oriented development policies, the success of these policies will depend upon having better inter-county transit connections.
— JAB