Northern extension of Beltway Express Lanes discussed, Maryland study of Tysons/I-270 XLs

September 20, 2012

2012-09-19: With the Capital Beltway's toll express lanes due to open by December there will be twelve traffic lanes (2x4 free lanes and 2x2 toll lanes) between northern Virginia's Springfield Interchange at I-95 and just beyond the Dulles Toll/Access Road VA267 near Tysons Corner - 14 miles. From there for three miles north to the Potomac River it's back to eight (2x4) lanes.

Reasonably enough people are asking about the big lane drop just north of Tysons Corner. How will 12 go into 8 lanes, or more precisely six northbound lanes go into four. The American Legion bridge across the white water section of the Potomac into Maryland at Cabin John has ten (2x5) lanes but the fifth lane each direction is  dedicated to travel on and off the George Washington Parkway - Marylanders major route to Washington DC, CIA HQ and the Pentagon.

Then north of the bridge there's another four miles of the Beltway in Maryland with over 200k/day up to the I-270/Beltway split.

230k veh/day

The American Legion bridge in this stretch carries around 230,000 vehicles a day average. That makes it one of the busiest bridges on the east coast after the George Washington Bridge (NY-NJ) and comparable in daily traffic to the west coast's busiest - the San Francisco Oakland Bay Bridge. Of course it's not comparable structurally - at 1,400 feet long and about eight spans it's a fraction of their length and consists of concrete deck on steel I-beams, not unlike the construction style of many interchange bridges.

In response to media stories and public concern elected representatives have been calling for something to be done. The heads of Fairfax County Virginia (Sharon Bulova)  and Montgomery County Maryland (Roger Berliner)  issued a statement this week saying they had written to their state DOTs: "We request that the two DOTs work together to provide a plan for connectivity for this 7-mile segment that would go into operation as soon as practical."

Talking to Transurban/Fluor

Bulova said she may talk to Transurban/Fluor about extending their toll express lanes the seven miles north to the beginning of I-270 in Maryland. Two Montgomery County councillors Nancy Floreen and Hans Reimer  are supporting toll express lanes in this stretch.

Berliner was quoted as saying he's "not ready to endorse tolls" but said the county should take the initiative:  "Let's own our own destiny and take care of our destiny and see if we can come up with something we can agree on...With Montgomery and Fairfax taking leadership in this regard, we are taking an important step to show how we can improve the quality of life for our counties by working together."

Using shoulders

Berliner suggested as an interim measure shoulder lanes should be used to provide extra highway capacity, perhaps for buses and HOVs.

A problem: the American Legion Bridge itself has no shoulder. The travel lane edges are hard up against the bridge curb and concrete median.

The Beltway in this stretch is eminently widenable. Few buildings are close to it.

It's a tony area of large houses on large lots in a treed setting. Of course that doesn't mean there won't be NIMBY-type local opposition. 

Tony neighbors

The Beltway here has such neighbors as the Bethesda Country Club, the Burning Tree Club, Congressional Country Club, Scotts Run Nature Preserve, Langley Swim and

Tennis Club and a couple of parks.


The Virginia stretch has two interchanges - a diamond at Georgetown Pike VA193, and a trumpet at the George Washington Parkway.

On the Maryland side there are interchanges with the Clara Barton and Cabin John parkways and River Road MD190 plus the Beltway/I-270 spur split. So it is six interchanges.

With daily traffic well over 200k the Tysons-I-270 toll express lanes would need to be 2x2 so slowpokes can't block travel and to provide some serious extra capacity.

And as in the Virginia stretch they'd work best with dedicated ramps. Weaving across the general purpose lanes to enter or exit the express lanes would defeat much of the purpose of the extra capacity and add to safety problems.

earlier report:

includes MWCOG presentation:

TOLLROADSnews 2012-09-19

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