The Midtown underwater road tunnel lying beneath the Elizabeth River in Virginia, USA, is being replaced by a new tunnel that connects the cities of Norfolk and Portsmouth. Construction includes the relocation of a 91.5cm (36 inch) wide water main and the restoration of existing Downtown tunnels.
The Elizabeth River is tidal estuary, forming an arm of Hampton Roads harbor in southeast Virginia. The river is also a gateway to the south for the Atlantic Intracoastal Waterway – a sheltered waterway to Florida for commercial and recreational boating. The existing Midtown tunnel is a prominent highway between Norfolk and Portsmouth. It’s 50 years old and carries about a million vehicles every month, in excess of its design capacity.
The Elizabeth River Tunnels Project (ERTP) is being developed by the Virginia Department of Transportation (VDOT) in partnership with Elizabeth River Crossings OPCO (ERC) at a cost of $2.1 billion. The Commonwealth of Virginia is the owner of the project and ERC is responsible for the operation and maintenance of the Midtown and Downtown tunnels. SKW Constructors, a joint venture between Skanska, Kiewit and Weeks Marine, is the design-build contractor. SKW Constructors awarded the horizontal directional drilling work to the Michigan-based Mears Group in recognition of its status as one of the largest horizontal directional digging (HDD) contractors in the world.
Part of the new road tunnel project involves building a new water main. Replacing the old pipe included the fabrication, coating, testing and handling of the new pipe carried out by Mears’s subcontractor – Patterson & Wilder Construction. The first step in the project was to assemble a 152cm (60 inch) diameter casing to drill through, followed by the assembly of a 1,371 meters (4,500ft) long by 91.5cm (36 inch) wide water pipe. The pipe had to be strung out, the tie-ins completed and then using cranes and Volvo Construction Equipment (Volvo CE) PL4608 pipelayers, the pipe had to be lifted to the drilling rig and aligned with the orientation of the drill stem so the pipe could be pulled under the river.
“This is a fairly large project in terms of length and diameter and there can be environmental concerns involved in drilling under a river,” says Ed Kosarek, VP of Field Operations for Patterson & Wilder. “We chose Volvo CE’s rotating pipelayers because the machines are more versatile than any of its competitors for this kind of application.”
With the pulling forces exerted on different machines, the company wanted to ensure that capacity exceeded the requirement by at least 50 – so that the operation would be safe and successful.
To reduce the impact on the environment, the project will follow Environmental Protection Agency and Commonwealth regulations. It will be built using ISO 14001 sustainable standards and an environmental management system will be used by Skanska.
The Volvo PL4608 pipelayer was more than up to the task, with its 80 ton tipping capacity and its hydraulically variable track gauge for stability at work and easy transport, making it the industry’s most adaptable pipelayers.
“In today’s economy, that’s the name of the game,” Kosarek. “You have to get it done smarter, quicker and safer. If you don’t then you are out of the game. The major difference between a Volvo pipelayer and traditional side boom dozer is the rotating function. The tracks can stay stationary, but the whole cab and boom of the machine rotates. There’s no other pipelayer that can do that.”
“The 360-degree swing capability suggests significant pipe-handling advantages including keeping the operator facing the pipe and it benefits from better stability with wider track gauge and a lower center of gravity,” adds Kosarek. “In addition to the unique 360° swing capability, the hydraulically elevating cab on the Volvo PL4608 can significantly improve operator visibility for increased site safety. Patterson & Wilder’s involvement in this project lasted three months but work on the tunnel itself is scheduled for completion in 2016. The project will enhance the transportation network in the Hampton roads region and is expected to generate about 1,700 jobs.
Picture 1: The Volvo pipelayer holds up its side of the bargain
Picture 2: The pipe is held stationary in the air
Picture 3: The water main is steady and supported