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Toll lane critics cite possible flaws in Maryland traffic analysis

Opponents of widening I-270 and part of the Beltway say the federal government should order an independent review of the state’s analysis

Maryland plans to add toll lanes to the western part of the Capital Beltway and Interstate 270, seen here near where the two highways meet. (Katherine Frey/The Washington Post)
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Critics of Maryland’s plan to widen Interstate 270 and part of the Capital Beltway with toll lanes cited possible flaws in the state’s analysis of whether the new lanes would relieve traffic congestion, saying the federal government should order an independent review.

In a Monday letter to the U.S. Department of Transportation, transit advocates said the state hasn’t explained why its latest computer traffic models produced “substantially different” results from an earlier study. The more recent findings, critics said, further support the state’s argument that the highway widening would reduce backups. However, they said, numerous discrepancies appeared designed “to obtain a desired result.”

The traffic modeling was done as part of a federally required “final environmental impact statement” (FEIS) that the state released last month regarding Maryland Gov. Larry Hogan’s plan to alleviate traffic congestion. State officials have said the highway widening also would free up more room in the regular lanes, but critics have said it would attract additional traffic and exacerbate climate change.

In the letter, Ben Ross, chair of the Maryland Transit Opportunities Coalition, said the Maryland Department of Transportation declined to explain the different findings or changes in its modeling. The “anomalies,” Ross wrote, “create serious doubt whether the new traffic forecasts could have been generated by correcting previous errors and suggest possible falsification of model outputs.”

Project spokesman Terry Owens said the traffic analysis was reviewed by experts and “followed accepted professional practices” approved by the Federal Highway Administration.

The latest regional traffic model used in the analysis “follows industry standards and has been thoroughly reviewed and validated,” Owens wrote. MDOT, he said, “has provided a vast amount of high quality data supporting the FEIS.” The state’s efforts, Owens wrote, “far exceed the [federal] requirements.”

In releasing the FEIS, MDOT said it had “modified analysis methodologies” and “conducted new analysis” based on public comments it had received. The state did not elaborate.

Maryland toll lanes wouldn't ease evening traffic without other improvements, study says

Ross, a Bethesda resident who is retired from reviewing computer models for groundwater flow, said he found the problems “buried in a blizzard of numbers” in an appendix of the state’s FEIS released last month.

“The numbers simply do not look like what a computer model would produce,” Ross said in an interview.

In one example, Ross said, the state’s latest analysis found “drastically” improved drive times on the Beltway’s inner loop during the evening rush between Connecticut Avenue and Interstate 95 compared with its previous analysis. However, he said, the calculations didn’t appear to consider, as traffic models typically would, that more motorists would switch to the faster Beltway from other roads to save time, which would add traffic and slow speeds.

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The critics’ accusations come as the Federal Highway Administration considers the project’s FEIS for approval. Environmental approval is required to receive federal funding and typically is a target of federal lawsuits seeking to block major infrastructure projects. Questions over Maryland’s ridership projections for the Purple Line, which is more than four years behind schedule and $1.46 billion over budget, were at the heart of a legal challenge that delayed the light-rail line construction by almost a year.

MDOT needs the federal environmental approval before it can secure a 50-year contract worth billions for a private consortium led by Australian toll road operator Transurban to build the lanes. Project supporters say Hogan (R), who is term-limited, is eager to secure the contract before he leaves office in January, when a new governor could change the plan, slow it down or stop it.

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MDOT’s first contract on the project also is being challenged in court, where a losing bidder has alleged that the state improperly awarded a “predevelopment agreement” to the Transurban team to design the lanes and negotiate the longer-term contract to build and operate them.

Under MDOT’s plan, the state would add two toll lanes in each direction to the Beltway between the Virginia side of a new and expanded American Legion Bridge and the exit for Old Georgetown Road in Bethesda. From there, the lanes would extend up I-270 to Frederick, with the lower part to I-370 being built first.

The regular lanes would be rebuilt and remain free. One of the toll lanes on lower I-270 would come from a converted carpool lane.