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The recent ribbon-cutting ceremony marking completion of the design-build phase of the $2.1 billion Elizabeth River Tunnels (ERT) project in Norfolk, Va., was an event worth noting for many different groups:

  • Drivers who rely on the tunnels to travel between Portsmouth and Norfolk are now benefiting from the speedy construction, which added sorely needed capacity to one of the region’s busiest crossings and was completed an entire year ahead of schedule.
  • Construction professionals are looking at the unique design using all-concrete immersed segments that innovative engineers employed to address a particularly challenging construction environment.
  • Policy makers can learn how a deal that brought in private-sector funding and expertise with a public-private partnership (P3) can help to solve urgent public-sector infrastructure needs.

A tunnel element is floated out from the graving dock.

Virginia Secretary of Transportation Aubrey Layne said that the ERT project is “fantastic. It brings needed congestion relief to the citizens here. It also helps the military, our economy, and the port.”

One key economic benefit to the region from this project is jobs. ERT produced more than 500 project-direct jobs, more than 1,000 indirect jobs in the community with related industries and suppliers, and more than 200 permanent facilities, maintenance, and operations jobs.

Some of those jobs came from an on-the-job training component included in the contract to the project. While the Virginia Department of Transportation (VDOT) required that 70 individuals complete the program, SKW Constructors put 86 people through the program. Seventy-three percent of the students reside in Hampton Roads and 60.5 percent are minorities.

The completed ERT project features a new two-lane tunnel adjacent to the existing, refurbished Midtown Tunnel under the Elizabeth River connecting the communities of Norfolk and Portsmouth. This two-tunnel configuration, along with enhanced access roads, provides urgently needed additional capacity for a road that had been considered the “most heavily traveled two-lane road east of the Mississippi,” according to VDOT. Traffic on the road has increased by 600 percent since opening of the original Midtown Tunnel more than 50 years ago.

The renovated tunnels are also a significant safety improvement. The original Midtown Tunnel had two lanes of traffic, one in each direction, with trucks comprising much of the traffic. Now, eastbound and westbound vehicles flow in separate, two-lane tunnels. The rehabilitated Midtown Tunnel carries two lanes of eastbound traffic from Portsmouth into Norfolk; the new Midtown Tunnel handles two lanes of traffic heading west.


Construction

There were four major elements of the Elizabeth River Tunnels Project:

  • a 3,800-foot-long, two-lane tunnel constructed adjacent to the existing Midtown Tunnel;
  • a one-mile extension of the Martin Luther King Jr. Freeway — an elevated four-lane, north-south expressway with a raised median connecting U.S. 58 and the Midtown Tunnel to I-264 and the Downtown Tunnel;
  • upgrade of the two Downtown Tunnels; and
  • renovation of the existing Midtown Tunnel to reconfigure it to two-lane traffic in one direction and upgrade its performance and safety.

In its role as design-build contractor for the project, SKW Constructors (a construction joint venture led by Skanska and including partners Kiewit and Weeks Marine) faced challenging technical, logistical, and environmental factors. While building the new Midtown Tunnel, these started with dredging the trench in which the new tunnel would be placed. Using a large crane and clamshell bucket, trenches were excavated on land and at the bottom of the Elizabeth River, digging in water as deep as 95 feet. Existing abandoned timber piles and shoreline debris were removed along with 1.2 million cubic yards of sediment from the water.

As part of SKW’s commitment to environmental stewardship during construction, the team developed an environmentally friendly way to treat lead-contaminated sediment onsite; implemented innovative methods to recycle leftover concrete, including the use of waste concrete to form oyster boxes for development of oyster spats in the Elizabeth River; and adopted environmentally friendly oil for use in marine equipment.

The new Midtown Tunnel recently opened to traffic.

When determining where to position the closure piece of the tunnel elements, SKW decided to move the closure to the Norfolk end, rather than having the elements meet in the middle of the river. This allowed the team to tie in the last tunnel element and the Norfolk approach in a dry environment, and thus avoid any negative impact on naval and commercial marine traffic in the channel (the U.S. Navy operates the world’s largest naval station out of Norfolk).

Another significant decision in the project came in selecting the material used for the tunnel. Historically, all deep-water immersed tunnels in the United States have been traditional steel-shell immersed segments. This project used all-concrete immersed segments for only the second time in the United States. The precast concrete tunnel allowed for a reduction of the overall height of the tunnel elements, which resulted in less dredging, making the process more economical, while increasing flexibility in design and transport of the tunnel elements.

The team had to meet a 120-year design life performance requirement by developing a concrete mix design for the tunnel elements in an extremely corrosive environment without the use of corrosion inhibitors. The tunnel itself is made up of 11 precast concrete, rectangular elements, each approximately 342 feet long, 28.5 feet tall, 54 feet wide, and weighing 16,000 tons. Each element was cast in a graving dock in Sparrows Point, Md. near Baltimore and floated 220 nautical miles down the Chesapeake Bay to the construction site in Portsmouth.

Once they arrived onsite, the elements were prepared for immersion and then placed in a large catamaran-style lay barge. A controlled descent lowered the elements to the bottom of the river through the use of ballast. Careful coordination between the lay barge operators, survey personnel, and underwater divers allowed for precise placement of the elements until they were resting in their proper location on the bottom of the excavated trench.

In rehabilitating the existing Downtown and Midtown Tunnels, the team installed fire protection board to the ceiling and jet fans to replace and enhance the tunnel ventilation system, upgraded the tunnel lighting system with LED lights, and added a new traffic management system..

Once in position in the trench at the bottom of the river, the elements were linked and sealed to keep them watertight. A steel ring on one end of an element was placed next to an O ring, or Gina gasket, on the end of an adjacent element. Once the elements were connected, water from between the bulkheads was removed and the resulting vacuum squeezed the gasket to create the watertight seal.

As crews placed a newly immersed element adjacent to a previously immersed and positioned element, the Gina gasket would compress. Another rubber seal, an Omega gasket, was then placed on the inside junction of the elements. This enabled the tunnel to handle twice its expected load. After the team verified the secure placement and functionality of the Gina and Omega gaskets, the junctions were encased in concrete to provide a structural cover.

After the tunnel elements were placed in position at the bottom of the Elizabeth River, SKW removed the ballast water, poured concrete in the bottom of the tunnel to create the curvature of the road, and then paved the road surface on top. The SKW team then applied a three-part backfill operation along the sides and top of the immersed tunnel elements in the trench to prevent horizontal movement, provide a protective cover, and add an additional layer of protection against scour and marine impacts.

The new Midtown Tunnel features an emergency exit corridor that runs parallel to the vehicular traffic tube. A series of exit doors are located every 300 feet in the tunnel to lead drivers and passengers from the roadway to the egress corridor and out of the tunnel in case of an emergency. This corridor may also be used by emergency responders if they need to enter the tunnel.

In rehabilitating the existing Downtown and Midtown Tunnels, the team performed maintenance and made life-safety improvements. They installed fire protection board to the ceiling and jet fans to replace and enhance the tunnel ventilation system, upgraded the tunnel lighting system with LED lights, and added a new traffic management system. With these improvements, the SKW team decreased the construction time by starting that work while the new tunnel was under construction and working on evenings and weekends. Rehabilitation of the Downtown Tunnels was completed four months ahead of schedule. Rehabilitation of the existing Midtown Tunnel was completed one year ahead of schedule.

Construction activities on the MLK Freeway Extension in Portsmouth included widening of the roadway and bridges on I-264, replacing the pedestrian bridge over I-264, extending the MLK Freeway from London Boulevard to I-264 via an elevated highway with an interchange at High Street, and installing aesthetic treatments from Turnpike Road to London Boulevard.

Extending the MLK Freeway from London Boulevard (where it previously terminated) to I-264 provided a more direct access between the Midtown and Downtown Tunnels and added a shorter, more direct route (above the city streets in Portsmouth) to the tunnels from Portsmouth. These changes allow motorists to easily choose between the Midtown or Downtown Tunnels and better communicate traffic conditions via changeable message signs on the MLK Freeway.

So, what is the end result in the newly completed ERT project? The average round-trip commuter is saving about 30 minutes a day, as well as reducing fuel consumption and emissions. Greater ease of travel and increased travel options, thanks also in part to an increase in the frequency of mass transit routes, is providing greater accessibility to jobs, educational institutions, health care facilities, shopping, and recreational activities.

This will have great significance to the Hampton Roads area, a region of more than 1.7 million people and home to the U.S. naval base in Norfolk; major Air Force, Army, Marine Corps, and Coast Guard facilities; and several marine terminals in Portsmouth and Norfolk. Successful completion of the ERT project serves a critical need for motorists, the region’s economy, the efficient movement of goods and services, and the overall quality of life in Hampton Roads.

Skanska’s involvement does not end with completion of construction, cutting of a ribbon, and the steady stream of cars traversing its completed tunnels. Part of the agreement with the VDOT includes an ongoing investment through the life cycle of the project with operation and maintenance of the tunnels. With terms already negotiated before construction, Elizabeth River Crossings OpCo (a joint venture concessionaire of Skanska Infrastructure Development and Macquarie Group) will use private-sector technical, management, and financial resources to provide ongoing regular maintenance without a lengthy procurement process and unaffected by future governmental budget changes.

A successful P3

As states and municipalities around the country face decisions about how to finance and prioritize critical infrastructure needs, the lessons from the ERT project are under careful observation. As one of the largest P3 projects in the United States, at $2.1 billion, and the country’s first P3 tunnel project, the ERT project illustrates how these collaborative projects can help the public and boost the local construction economy.

Its success is a good reflection of the benefits provided by the P3 model, which can serve as an excellent tool to finance, design-build, operate, and maintain infrastructure projects. Subject to the terms of the agreement, the private-sector partner assumes more responsibility for a project’s outcome and financial health by investing its own capital, while the public sector benefits from a fixed price, specific timelines and deadlines for delivery, and guaranteed performance-based operations and maintenance contracts.

Delivering a project as complicated and demanding as the ERT with such an emphasis on quality and safety is a notable accomplishment. Doing so as quickly as SKW was able to do is a testament to the effectiveness of the joint-venture partnership and of efficient planning and execution that was both thorough and flexible. The project relied on technical expertise, engineering and design innovation, and efficient supply chain management. Its success entailed deployment of the right people and engaging them in a safe work environment that allowed a brisk work rate. The ERT will serve the Norfolk/Portsmouth area for years to come, standing as a testament to the ingenuity and workmanship of the many people involved in making the project a reality.


Wade H. Watson is vice president – Operations for Skanska and project director for SKW Constructors, the design-build contractor for the ERT Project.

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