By Peter Samuel
Washington DC area woes:
the Wilson Bridges world class snarls
The Wilson Bridge replacement is the largest toll crossing projects presently in train in the U.S. Shes a $1.6 to $2.1 billion project in total, involving a major new river crossing, either 10 or 12 lanes wide, and tricky reconstruction of 4 miles of approach highway, including four major interchanges, and lots and lots of politics at three different levels of government.
As for tolling, four toll plazas involving 28 toll lanes and extensive use of electronic collection is assumed by engineering and planning staffs involved in studies of alternatives.
The obsolete I-95 Wilson bridge on the Washington Beltway linking Maryland and Virginia is the Washington DC metro areas principal highway problem. Only six lanes wide this bridge carries 170,000 vehicles a day for many hours at creep & crawl, stop & start designated as Level of Service E or F.
The Wilson Bridge must be way up there in any world ranking of daily per lane traffic volume -- 28,300 vehicles per lane per day. Those wimps in New York dont know what traffic congestion is compared to us Mid-Atlantic folks! Their George Washington Bridge carries 16,400 (230,000 on 14 lanes), the San Francisco Bay Bridge 22,500 (225,000 on 10 lanes) and the New Jersey Turnpike carries a mere 13,300 (160,000 with 12 lanes). Only some of the most congested LA freeways, Torontos H401, and the London Orbital motorway M-25 have congestion like Washingtons Wilson Bridge. The motorway the Brits curse has almost identical volume and laneage to our Wilson. And they dont have to call everything to a stop to raise a draw bridge 200 times a year either, like we do on the lower Potomac.
Thankfully an excellent solution is in the works: the steady deterioration and certain collapse of the structure into the mud of the Potomac before too long! A new monument just off the Mall: the Gridlock Monument!
The bridge has sown the seeds of its own destruction by its deck sinking except at its expansion joints, so that, day and night, big trucks bounce at the joints and pound its pavement and stress its structure. Stringers and beams flex and rotate, tearing at welds. The bridge noticably squeaks and sways. Consultants have said major rehab will be needed within a few years 2004 is one deadline or it will have to be closed to big trucks.
35 years old the Wilson Bridge was designed just for Beltway (I-495) traffic: an eventual 75,000 v/day they said. But it has been the great accomplishment of 1960s anti-highway activists that by aborting the completion of partly built expressways inside the District of Columbia, they not only beat up the economy of the District and encouraged the very suburban sprawl they so often decry, giving the national capital a kind of doughnut character, but they also concentrated ridiculous volumes of traffic on the Beltway. When the Wilson Bridge was being built six lanes made eminent good sense. The Beltway itself was four lanes on either side of the river and the extra two lanes on the bridge helped provide for the local traffic of US-1 on the Virginia side or I- 295/MD-210 traffic on the eastern side.
From the south I-95 was built as a splendid expressway barrelling right through the Beltway interchange at Springfield Virginia continuing northeastward as an eight-laner (Shirley Highway) with worldclass spaghetti bowls of interchanges by the Pentagon, then over the Potomac on the 14th Street bridges 8-lane pair and up the Districts Southeast/Southwest Freeway, diving right under the Mall just a couple of hundred yards west of the Capitol Building, going right underneath the Labor Department offices and... then coming to a complete halt. Up on the northeast corner of the Beltway in College Park MD where I-95 comes down from Baltimore all the ramps and bridges for its link to the District were complete and waiting. They wait still! The eight mile link was never built, though in the late-1980s a few hundred yards of extra roadway was built to take it to a surface arterial, New York Avenue NE. Instead of travelling 22 miles straight through the District I-95 through traffic generally goes 37 or so miles on the Beltway circle route never touching DC. East and west are about the same distance but the western route has had its Potomac River bridge at Cabin John widened to 10 lanes, while difficulty in getting agreement on a design has stymied all action on the Wilson.
Blockages extend to local streets
Not only do the eight lanes of mainline beltway traffic have to merge down to six lanes on the Wilson Bridge but four major interchanges in 5 miles insert large volumes of extra merging and weaving traffic. The backups get so bad sometimes that vehicles simply attempting to travel over the mess get blocked in Alexandria because of backups on the ramps and on the roadways approaching the ramps. The accident rate on the bridge is twice that of the rest of the Beltway. Ideally the situation would be relieved by construction elsewhere, but whereas most metropolitan areas are building outer highways or bypasses the Washington area vies only with the San Francisco Bay area in spinning fantasies about transit being a substitute for new highways. Maryland is the major problem. US-301 to the east is obviously a corridor needing upgrade, and which could relieve pressures on the Beltway. To the west the Virginia government is preparing to bite the bullet for its part of a major western bypass of the Washington area it would take off from I-95 somewhere in the region of the Quantico Marine base, go one side or another of Manassas, probably go just west of Dulles airport, and interchange with the Dulles Greenway near Leesburg.
However thats about where it will end, says the Virginia government, which has had no success in getting Maryland to cooperate in planning a Potomac crossing and connection to I-70, which is connected to Baltimore and via its Beltway to I-95. And despite the feds oft-advertised role in planning a national highway system none of them has lifted a finger to try establish an acceptable Virginia-Maryland corridor on the northwest fringe of the Washington metro area. The most likely future scenario is that conditions will continue to worsen on the existing route, US-15, which on the Virginia side is a 2 lane difficult-to-widen road and on the historic steel truss 20 wide bridge over the Potomac at Point of Rocks. From there on, in Maryland, US-15 will be readily widened and upgraded to limited access status once an administration is elected that is less besotted with light rail as the panacea for every transportation problem. My own little town of Frederick will then need a Los Angeles or Houston style multi-level mixer to sort out the many movements generated by I-270, I-70, US-15, US-340, all of which are expressways at this point. A better plan would be to find a more direct but separate corridor for the western bypass crossing the Potomac near Dickerson, then following the Montgomery/Frederick county line northeastward toward I-70 joining it near Newmarket or Mt Airy. But Marylands government too busy playing trains wont consider such highway planning.
So for the time being traffic will continued to be channeled through the old Beltway corridor making reality out of all the political metaphors about Beltway gridlock. In these circumstances the engineers and planners are doing the best they can. There are no construction challenges here, just political. The river at the Wilson bridge is a shallow tidal channel 4,000 feet wide, 3,600ft of it 4 to 10 feet deep with the main river flow confined to the western 400 feet, on the Alexandria side. The challenge is esthetic and economic: how to design a crossing that can carry 250,000 vehicles a day right on the edge of an outstandingly preserved 18th century port town, and provide not just for that crossing but for four nearby interchanges. The effort to get agreement between various levels of government about the nature of the replacement has been going on for eight years, but there seems a good chance that a committee representing them all will meet an October 1996 deadline set by the U.S. Congress for an agreed plan.
Alexandria representatives initially were adamant that a tunnel was the way to go. Consultants advised that the four tube tunnel (each with 3 lanes) would cost around $3 billion, take 8 years to build and was not viable for toll financing. State officials opposed it because it would divert hazardous materials trucks elsewhere, while bicyclists and pedestrians opposed the tunnel because it would exclude them. A fixed span 'high' bridge with 135 ft shipping clearance is difficult to build without its approaches and sheer mass overwhelming Old Town Alexandria with its two and three story brick and wooden buildings. A new alignment half a mile further south was proposed with slightly lesser impact on Alexandria, but this doubled the length of the bridge, and disturbed a pretty natrual waterway and upset a whole new set of established waterfront residents.
Down to 3 alternates
At a two day 'retreat' earlier this month the committee narrowed its differences significantly. Though not an official consultant the T.Y.Lin company produced a new concrete arch bridge design that got more support than concepts produced previously by the hired consultants.
Alternatives now are:
(1) Two 6-lane high bridges with 135' shipping clearance, with the shipping channel moved closer to the center of the river, about $1.6 billion
(2) A single 6-lane high bridge with 135' shipping clearance for local traffic, 'hazmat' trucks, pedestrians & bikers and 2x3-lane tube tunnel for express traffic, about $1.6 billion
(3) A 6-lane 70' shipping clearance drawbridge for local traffic, 'hazmat' trucks, pedestrians & bikers combined with a 2x3-lane tube tunnel for express traffic, about $2.1 billion
A major design constraint for a fixed span bridge is the short distance between the last interchange on the Virginia side (at US-1 or Washington Street) which Alexandria insists must have the Beltway beneath it, and the middle of the river channel, which produce a 4 percent grade. Staff think by tweaking the interchange and channel width they may be able to get this down to 3.5 percent but that is still awfully steep for large long-distance trucks. The all-bridge option (1) seems flawed, and one of the bridge/tunnel combinations (2) or (3) the better solution.
The Beltway itself appears destined to undergo widening for a third time to become a dual-five lane facility and in the vicinity of the Wilson Bridge it is to be rebuilt New Jersey Turnpike style into a quad-three dividing the traffic into express and local, though the express lanes will have almost as many ramps as the locals, making for some spectactularly complicated interchanges.
2 toll concessions?
That leads to an interesting proposal: split the project into two separate toll concessions (1) an Express Lanes Tunnel and (2) the Local Traffic Bridge. The tunnel would guarantee uninterrupted faster trips and might sustain a higher toll rate, than the bridge. If the bridge were a high one the grade would slow traffic, while if it were a draw-bridge traffic would face periodic draw span raises. The prospect of competition between two separate concessionaires might help the project politically.
So long as there are alternate untolled routes it will be unrealistic to expect the projects to be financeable based on tolling alone, so the project is likely to involve a funding mix.
The Metropolitan Washington Council of Governments has modelled traffic flows at $1 and $2 tolls on the Wilson crossing with the alternates untolled. The reduced demand at the Wilson is spectacular. Without a toll the Wilson crossing would face demand for 290,000 to 300,000 vehicles/day in 2020. That non-tolled traffic volume would justify 16 lanes by the normal engineering criteria. A $1 toll would reduce that 2020 traffic 30% to about 210,000, and a $2 toll by a spectacular 60% to about 120,000, according to the MWCOG modelling. In the last case youd get by OK with 8 lanes, perhaps with an extra lane on each side for the merging and weaving and for reserve margin? Maybe a 6 lane bridge and 4 lane tunnel would be plenty?
The major challenge in attracting private sector financing may be establishing some ground rules about what else will be done for the system. MWCOG estimates the tolls will have limited impact in stimulating transit use because trips are too dispersed to be effectively served by it. Diversion to the western Beltway route is limited by an assumption that the western Cabin John crossing will not be widened beyond the current 10 lanes, so growing congestion will limit any diversion. Inside the Beltway crossings will carry between zero and 15% more. The major impact of the toll will be reducing total trip demand people will rearrange their affairs, where they work and shop etc, to do less river crossing 15% in the case of $1 and 25% in the case of $2. If motorists pay something like the social costs of crossing in their tolls, then perhaps that reduced crossing is a desirable social outcome? The tolls will be rationing a scarce resource as a marketplace is supposed to. (An official contact: Komal Dewan, Wilson Bridge Study & Design Center, 211 N Union St Alexandria VA 22314, tel 703 519 9800 fax 703 548 4593.)