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.
A main water feature
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.