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Dryden Bypass project. (Engineering Notes).

Value engineering project saves more than a million. The new $26-million four-lane, 2.8-mile Dryden Bypass project was originally designed with two large 600-ft long traditional bridges suspended 90 ft over State Route 743 and a nearby creek, Clear Spring Branch. The problem with this solution was its price tag of $6 million. Bridges can be expensive, especially when they must span from the top of one mountain to the top of the next, as was the case in this project.

Cleco Corporation (Rosedale, Virginia) partnered with CONTECH Construction Products Inc. (Middletown, Ohio) and Anderson and Associates, Inc. to propose an alternative to the original bridges using a value engineering approach, which focuses on the lowest lifecycle cost consistent with performance, quality, and reliability. The process enlarges the number and scope of available alternatives, resulting in lowered costs and often, accelerated project completion. The Virginia Department of Transportation (VDOT) encourages value engineering projects and is one of the largest and most effective users in the U.S. A significant reason for its success is that VDOT returns 50 percent of the savings to the contractor.

The proposal eliminated the two bridges by recommending the installation of a 450-ft long CONTECH[R] Multi-Plate[R] steel roadway tunnel and a large, steel drainage structure. Instead of Route 743 going under the bridges, the two-lane road would pass through the tunnel, which would be under 63 ft of hill. After installing a paved roadway inside the 24-ft diameter tunnel, it would easily accommodate permitted, over-sized loads for modular housing and the average daily traffic traveling on Route 743. Additionally, as part of the design proposal, the tunnel included a fire hydrant, lighting, and drainage.

The drainage structure consisted of five 84-in. diameter steel pipes 410-ft long, under 95 ft of cover, to carry the 100-year storm water volume in Clear Spring Branch. The drainage pipe was fabricated from seven-gauge steel plate with a five-gauge invert to meet a minimum 100-year design life.

An advantage of Cleco's proposal was that a large portion of the nearly 260,000 cubic meters of excess earth cut from other parts of the project would be used to backfill above the tunnel and drainage structure instead of being hauled away.

The state approved the proposal based on the technical merits and cost savings of approximately $3.8 million in initial costs and reduced long-term maintenance. Cleco was awarded 50 percent of the cost savings by VDOT, which to date is the largest value engineering project in Virginia's history.

Work began on the project in early spring with the steel plates arriving in May 2001. After two weeks of excavating the site and preparing the bedding for the foundation, Plate Erectors (Pittsburgh, Pennsylvania) assembled and erected the tunnel from the 3/8-in. thick, hot-dipped galvanized corrugated steel plates. Backfill was then placed around and over the structure with an inspector on site during the complete process to ensure the quality, method, and placement of the backfill did not deviate from the project plans.

Through value engineering of the Dryden Bypass bridge, VDOT will bring in a completed job at a savings of nearly $2 million to tax payers--even after awarding the contractor its share. The work is part of a total $26-million project that includes the construction of five bridges over the CSX Railroad, Route 619, and the Powell River. Project completion is scheduled for December 1, 2002.
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Title Annotation:Virginia Department of Transportation project
Publication:Public Works
Geographic Code:1U5VA
Date:Oct 1, 2002
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