More Lanes Alone Won’t Clear Up the Highway

More Lanes Alone Won’t Clear Up the Highway

A study commissioned by the federal government found that adding a lane on either side of a highway connecting Baltimore and Washington, D.C. wouldn’t alleviate traffic. Why lawmakers should focus on other types of inter-urban transit to better connect the two cities.

A segment of the Baltimore-Washington Parkway. Doug Kerr on Flickr

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This post originally appeared on Greater Greater Washington.

Widening the Baltimore-Washington Parkway would let it carry more vehicles, but would not make traffic any better. That’s the conclusion from a federal study that looked at adding a third lane in each direction.

The study, by the Federal Highway Administration (FHWA), looks at widening the parkway between Route 50 and the Baltimore Beltway in Maryland. FHWA will be sending the results of the study to Congress soon.

FHWA is studying the widening because Rep. Dutch Ruppersburger (D-Md.) inserted an earmark into the FY 2010 federal budget. There’s no actual proposal to widen the parkway (at least not yet).

There’s a very good chance that nothing further will come from the study. And that’s the way it should be. The region does not need to invest hundreds of millions in this corridor simply to move more cars. Increasing mobility means moving more people, and here that should mean improving transit options—something this study didn’t look at.

The study looked at four options for widening the parkway in addition to a no-build alternative. Two alternatives looked at adding a lane in each direction in the median. The other two alternatives studied adding a lane in each direction to the outside of the roadway. Space constraints mean that any widening requires a combination of both inside and outside widening as well as rebuilding numerous overpasses and underpasses.

The difference between the two inside and two outside designs is in design standards. For each type of widening, the consultants looked at AASHTO-compliant standards and National Park Service standards.

The AASHTO options called for adding a 12-foot wide travel lane, a 10-foot wide outside (right) shoulder, and a 10-foot wide inside (left) shoulder. The NPS options included adding a 12-foot wide travel lane, an eight-foot wide outside shoulder with curb and gutter, and a three-foot wide inside shoulder with curb and gutter.

Estimated costs ranged from a high of $565 million for the AASHTO outside widening option to a low of $343 million for the NPS inside widening option.

Despite the investment, though, the study shows that the parkway would be just as congested as it is today by the year 2040. FHWA expects any increase in capacity to be matched by a corresponding increase in vehicle trips. A widened parkway would carry more cars, but it ultimately wouldn’t shorten people’s trips.

Widening the parkway is the wrong approach from a growth perspective, too. Maryland’s Prince George’s County has long had a problem focusing growth in the “developed tier.” Adding freeway capacity will only increase the pressure to build in parts of the county and the region that do not have the infrastructure for it.

Adding lanes to the parkway would also hurt the developed communities it passes through. In many places, it already forms a significant barrier between neighborhoods. More traffic and more pollution along the roadway will hurt many residents and the pastoral image the National Park Service believes the parkway should exude.

Staff at the meeting stressed that further studies would need to look at options beyond just widening the parkway. Other options could include improvements to transit, other roadways or spot “improvements” along the parkway.

If any money were available for widening, it would be better spent on improving transit between Baltimore and Washington. Maryland could speed up trains on MARC and Amtrak’s Northeast Corridor and add capacity for more trains, extend the D.C. Metro’s Green Line or create incentives for carpooling.

As the region continues to grow, we need to focus on building livable and walkable communities. Widening a freeway encourages traditional sprawl, and it sends the wrong message about the region’s priorities.

Comments on the study are still being accepted, though only for the next 2-3 weeks. If you have thoughts on whether the parkway needs extra lanes, you can submit written comments on the project’s website.

The next step for the project team is to finalize a report to Congress showing the estimated costs, benefits and impacts of adding a third northbound and third southbound lane to the roadway. Beyond that, it’s up to Congress to decide whether to leave the parkway as-is, undertake further study or begin to plan for construction.

Tags: infrastructurewashington dcparkstrainsbaltimorehighwaysamtrak

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