How do you build a tunnel under a river? Explore how we’re submersing 16,000-ton segments to create the Elizabeth River Tunnels in Virginia. Read the full story here:

Faster and safer for 100,000 daily drivers

Elizabeth River separates the adjacent cities of Norfolk and Portsmouth, which lie on either side of the river. There are few bridges here and the tunnel that was built 50 years ago—when there were fewer cars than today—now constitutes one of the busiest two-lane thoroughfare in the eastern U.S. Around 100,000 vehicles pass under the river every day. The queues are long and traffic moves slowly.

A couple million people live in this region, called Hampton Roads, and the channel is traveled by both naval and merchant vessels. Norfolk is home to the world’s largest naval base and the container terminals make Norfolk the third largest cargo port in the U.S.

A time thief

"I lose close to an hour a day in traffic," says Major Dudley III, who drives his long container trailer between ports and logistics centers eleven or twelve hours a day. "It will be great when the new tunnel is finally open."

The new tunnel is like a Lego puzzle of eleven prefabricated tunnel sections each around 104 meters in length. The new tunnel will increase capacity and improve traffic flow.

A boost for old tunnels

But Major Dudley will have to wait until 2016. That is when today’s Midtown Tunnel will have two tubes with two lanes in each direction. A few miles away, the rehabilitation of the two Downtown tunnels is part of the scope.

One of the two-lane Downtown tunnels (the westbound tube leading from Norfolk to Portsmouth) was rehabilitated last year. It is brighter thanks to efficient LED lighting and it is higher because the new jet fans do not require a false ceiling. This is a clear boost for drivers who can now also look forward to the other Downtown tunnel (the eastbound tube leading from Portsmouth to Norfolk) being upgraded in 2015.  

Billion dollar project

The construction contract is worth USD 1.5 billion, of which Skanska has 45 percent in an integrated joint venture (known as SKW Constructors) with Kiewit and Weeks Marine. Both partners are known to Skanska from previous collaborations.

The construction project is divided into five different segments, each one with a separate project team and project manager.

"In an undertaking as big as this one it’s much more efficient to divide the project up into more manageable parts," says Wade Watson, Skanska’s Project Director. The segments are also all completely different.

 Fabrication Segment:  Prefabricating the tunnel elements in a dry dock at a disused shipyard in Sparrows Point, near Baltimore, then floating and towing them 220 miles down the Chesapeake Bay to the project site. The eleven tunnel tubes are approximately104 meters long, 8.7 meters high and 16.5 meters wide. They weigh 16,000 tons each.

Marine Segment:  Marine work such as dredging and preparing the river bottom, placement, immersing and securing the tunnel sections.

Approaches Segment:  Building approach roads to the new tunnel on both sides of the river.

Interiors Segment:  Rehabilitation and life-safety improvement of the interiors of the three existing tunnel tubes and technical installations in the new Midtown Tunnel tube.

MLK Segment:  Extending the Martin Luther King, Jr. Expressway, which will relieve local streets of traffic to and from the tunnels in Portsmouth.

At the end of 2014, the various segments of the project were at different stages. Six tunnel elements had been fabricated and floated down the Chesapeake Bay to Portsmouth. Immersion of tunnel elements is under way with elements 1, 2 and 3 immersed and the other three elements moored at the wharf awaiting  their turn. The five remaining elements are in production at Sparrows Point where work will be concluded in spring 2015. Rehabilitation work is complete on one Downtown Tunnel tube and underway on the other tube. The approach structure on the Portsmouth side is nearly finished, while the extension of the MLK Expressway (which was delayed slightly due to right of way issues) is now beginning to erect structural steel. But overall, the Elizabeth River Tunnels Project  is running 5–7 months ahead of schedule.

Like a big bridge

According to Wade Watson, the challenges are comparable to those for the big Arthur Ravenel, Jr. Bridge over the Cooper River, a construction project he headed in South Carolina ten years ago.

"It looks fairly simple but the details are complicated," says Wade as hedescribes a series of examples of the project’s challenges.

Concrete quality: The concrete needs to be durable to last for 120 years. To attain the right quality, the concrete casting process needs to use both cooling and heating; a balancing act, partly due to the fact that they are up to 90 cm thick, and partly because the concrete elements are made in both freezing and 30^oC temperatures.

Preparing the river bottom: To make sure that the bottom is level - involving millimeter precision,  - a special excavation technique is required when working in the strong currents and choppy waters of the river. 

The seams between tunnel sections: Double sealing with both compressed rubber packing and an exterior seal. Securing and protecting: Once in place the tunnel needs to be covered for protection against both dragging and dropping anchors and the impact of a sinking ship.

Ongoing health and safety training

Safety and the working environment are always in focus. This involves the continuous training of numerous subcontractors and their employees. It also involves work being halted by management or individual employees if there is any doubt about safety. Work does not start up again until improvements have been made or production methods changed to guarantee safety. A few suppliers that did not meet the strict health and safety requirements have been dismissed from the assignment.   

Toll fees via E-Z Pass

The project is partially financed by toll fees which were introduced at the beginning of 2014. The project owner, Elizabeth River Crossings (ERC), a company of which Skanska owns 50 percent, is collecting the tolls through a fully automated system. Drivers pay USD 0.75–1.25 per passage; the toll is higher during rush hour. The Commonwealth of Virginia is subsidizing a portion of the cost for the first few years. The concession will be in place for 58 years.

ERC is also responsible for operation and maintenance of the tunnels. Keeping all of the lanes – a total of around 50 miles – open and in good condition is necessary to generate income. Service vehicles can be dispatched for emergency assistance from the two control stations that monitor traffic. 

"We bear all of the market risk related to traffic volumes. More cars translates to more revenue and the potential for higher returns," says Doran Bosso, Asset Manager at ERC.

Traffic volume is already in line with the predicted 100,000 vehicles a day, which will generate income of USD 100 million a year. In ten years, an estimated 120,000 vehicles a day will use the tunnels.

The U.S. Roads & Bridges magazine named the Skanska joint venture’s Elizabeth River Tunnels public-private partnership project in Virginia as its top road construction project for 2014.

Skanska’s first Public Private Partnership (PPP) project in the U.S. – the Elizabeth River Tunnels in Virginia – is advancing both above and below ground. A new tunnel is being constructed under the river and three existing tunnel tubes are being upgraded.

Source: Skanska