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What is That White Thing in Tysons? How Does It Build The Subway?

It's Called a Truss

Virginia Megaprojects,* the state agency overseeing  the subway and HOT Lanes projects, sent along this explanation of those giant trusses that McLean residents marvel at.

Virginia Megaprojects, which is part of the Virginia Department of Transportation, also said that the HOT Lanes** (new toll lanes) are 55 percent complete.

The three giant horizontal cranes that dominate the skyline along Route 123 between McLean and Tysons Corner are impossible to miss. Crews are operating these football field-sized cranes to build the bridges that will carry Metrorail tracks along the northwest side of Route 123 and over the Capital Beltway in Tysons Corner.

A special white crane (really blue and white) is  building the spans across the Beltway using what is known as a “balanced cantilever” construction technique. The cantilever construction method is slightly different from the technique that is being used by the 366-ton horizontal cranes, also known as trusses.

Both types of cranes are lifting more than 2,700 large concrete segments to create the Phase 1 bridges. These segments are being made at a special facility on the grounds of Washington Dulles International Airport.

Railway construction will require frequent, overnight closures of both the Inner and Outer Loops of the Beltway; overnight closures are scheduled through fall 2011.

During this work, a minimum of two lanes will close. Three of four lanes will be closed in both directions on several occasions in July. Here's where to find out what lane closures are scheduled.

The two other trusses are bright yellow and blue. McLean residents have watched one blue and yellow truss build subway tracks down the median of the Dulles Connector Road, then make the turn over Route 123. The tracks are now heading west on Route 123 and heading for Tysons Corner.

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Background

*Virginia Megaprojects are a series of large-scale transportation improvements designed to ease congestion. The project include not only the HOT Lanes and the Silver Line subway, but also the widening of I-95, the I-95 Telegraph Road Interchange and the highway projects needed to ease congestion at the new Mark Center.These projects will completely transform the way we travel in Northern Virginia, according to the Megaprojects website.

**Fourteen miles of new HOT Lanes (two lanes in each direction) are being built on I-495 between the Springfield Interchange and just north of the Dulles Toll Road. These HOT Lanes will offer  HOV-3 connections with I-95/395, I-66 and the Dulles Toll Road for the first time. Buses, carpools and vanpools with three or more people, and motorcycles can ride in the new lanes for free. Vehicles carrying two people or less can ride them if they pay a toll. Visit www.virginiahotlanes.com for detailed project information.

SuperG May 07, 2011 at 02:23 AM
Can you stop calling it the "Subway"? It's called "Metro".

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