I-495 Extension Enters Homestretch
LOUDON COUNTY, Va. | Engineering News Record
With the successful installation of five 295-ft-long steel girder sets over a single weekend last month, a $660-million, 2.5-mile extension of the Interstate-495 Express Lanes in northern Virginia is now entering the homestretch.
Using cranes with a maximum capacity of 500 tons, crews installed the girders, consisting of 10 beams, over northbound I-495 to support a new express lanes ramp as part of the 495 NEXT project during the last weekend of January. Each girder is 11-ft tall by 3-ft wide, weighing between 70 and 80 tons. The girders comprise a new ramp at the I-495 interchange with the Dulles Toll Road leading to Dulles International Airport in Loudoun County, Va.
“This was far from a typical overpass,” says Richard C. Mayo, senior project engineer for Lane Construction Corp., the lead design-build contractor for Transurban, which holds a public-private partnership concessionaire agreement with the Virginia Dept. of Transportation. Subcontractor Shirley Contracting Co. led the interchange construction. Due to the dense urban environment and events such as the presidential inauguration, “we concluded we wanted a one-weekend operation rather than splitting the work into multiple weekends,” he says. The team met weekly with stakeholders for more than one year related to the planned “Big Beam” weekend, he adds.
Photo courtesy VDOT
Fabricated by High Steel Structures LLC in Lancaster, Pa., the five girder “lines,” consisting of four pieces each, required a complete assembly and disassembly in the yard before transport to Virginia to be spliced mid-air by a customized lifting rig.
“The girders came in lying on their sides due to their height,” says Michael Trabucco, vice president at Shirley. Upon arrival at the site, they were unloaded and positioned vertically. “Three segments in each girder line could be staged, picked and set; the fourth [curved] piece was staged on trailers,” he says. Temporary straddle bents and pier elements were built and configured around the existing I-495 alignment. Crews built a third temporary tower to support the girders in case of severe wind and placed up to 2 ft of material to flatten out the beltway surface for the cranes.
The weekend activities were planned “hour by hour,” Trabucco adds. Decision-makers regularly met at four check-in locations to determine whether to keep going. With no feared severe wind, crews completed the installation 2.5 hours early and turned the lanes back to VDOT by 2:30 am Monday.
Photo courtesy VDOT
Multiple Collaborations
VDOT launched an extensive public awareness campaign regarding the weekend shutdown, urging motorists to avoid northbound I-495 near Tysons Corner, Va. Multiple ramps at the I-495 and Dulles Corridor interchange were closed and detoured and all northbound regular I-495 traffic was reduced to two lanes and diverted to the northbound I-495 Express Lanes north of Route 123. For that weekend, tolls were suspended and trucks allowed on the express lanes.
The plan required extensive studies to determine which ramps to close and where, along with coordination among toll operators, police, Dulles airport staff and timing of traffic signals, notes Rimpal Shah, VDOT design-build manager. “We had a tow truck staged just in case” of traffic accidents and a dedicated ramp to be accessed only by emergency responders.
The state agency had anticipated a roughly 37% reduction of the 100,000 daily vehicles average through the interchange, but saw more than 40%, he adds.
The extension adds to the 14-mile express lanes on I-495 that opened in 2012. Transurban’s P3 agreement lasts until 2087, says Michelle Shropshire, state DOT megaprojects director for northern Virginia. “We have 94 miles of express lanes networks, three operators and dynamically tolled lanes,” she says. Vehicles with fewer than three people pay a toll to use the express lanes. Toll revenue has generated “millions of dollars of funding for enhanced transit over the years,” she adds.
Bruce & Merrilees is the electrical contractor on the project, led by Transurban. So far, more than 60 miles of tolled lanes for I-495 have been built, as well as for the I-395 and I-95 highways in the region through P3 agreements with Virginia, says Victoria Jones, Transurban project delivery director. The I-495 Next project, which also includes upgrades to the George Washington Memorial Parkway I-495 interchange, will introduce stormwater protection for existing toll lanes and Fairfax County road improvements. The extended toll lanes will open later this year with construction completion set for next year.
