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Elizabeth River Tunnels

WSP | Parsons Brinckerhoff is lead design engineer for the Elizabeth River Tunnels Project between Norfolk and Portsmouth in Virginia, US.

Elizabeth River Tunnels

CLIENT OBJECTIVE

Under a public-private partnership, the Virginia Department of Transportation (VDOT) partnered with Elizabeth River Crossings (ERC) to build a new Midtown Tunnel, rehabilitate the existing Midtown and Downtown Tunnels, and extend the Martin Luther King Freeway in the Hampton Roads region of Virginia.

CHALLENGE

The scale of the Elizabeth River Tunnels Project and its aggressive schedule required WSP | Parsons Brinckerhoff to form a design team with members—including 20 subconsultants—working in 33 offices.

The excavation site also presented three challenges:

  • Located near the existing, operating Midtown Tunnel, it was also within the confines of an active federal maritime channel with heavy traffic
  • Poor soil conditions required major pile formations or massive undercuts
  • An oyster reef near the excavation area had to be protected from exposure to sediment


Elizabeth River Tunnels

APPROACH


The Elizabeth River Tunnels Project includes:

  • Second Midtown Tunnel: The centerpiece of the Elizabeth River Tunnels Project is the new two-lane, 4,198-foot (1,280-meter) long immersed-tube Midtown Tunnel. We recommended an all-concrete option because it offered substantial economic savings. The tunnel—the first deep-water concrete immersed-tube tunnel in North America and the second all-concrete tunnel in the United States—comprises 11 hollow segments, called elements. They are lowered into the trench one at a time, each about a month apart. When the element, guided by a special barge, reaches the river bottom—a process that takes about 12 hours—a hydraulic arm pulls it together with the adjacent tube to form a watertight seal.
    When designing the tunnel, we incorporated safety features based on feedback from police, firemen, ambulance services and first responders. Enhanced emergency response and evacuation readiness were built into the design.
 
  • Rehabilitation and Upgrade of Existing Tunnels: To improve the safety and maintenance of the existing Midtown and Downtown tunnels, several improvements were designed, including:
    • Reversible jet-fan ventilation system to increase the fire size that the tunnels can handle
    • Protection of structural elements to improve life safety, provide a tenable environment during a fire event, mitigate structural damage and prevent progressive structural collapse
    • Drainage improvement to bring the Midtown Tunnel into compliance with stormwater and discharge regulations
 
  • MLK Freeway Extension: We designed a one-mile (1.6-kilometer) extension—an elevated four-lane north-south expressway with a raised median—providing access to the city of Norfolk via the Midtown Tunnel.
 
  • Intelligent Transportation System (ITS): We were involved in the design of the ITS for the Elizabeth River Tunnels Project.
 
  • New Water Main: We designed the relocation of 7,200 feet (2,195 meters) of a water main with a 36-inch (one-meter) diameter. Design and construction of the water main were completed within a tight 12-month time frame. Installation of the main was accomplished with zero environmental impact, minimal traffic impact to commuters and no closing of the river channel.
 

To coordinate the efforts of the design team and to maintain constant communication with the contractor, SKW, we instituted a rigorous communication system incorporating tools for collaboration, such as the firm’s secure web-based ProjectSolve2 system—which allows people working in various locations to share files and information—and ProjectWise, a computer-assisted design and drafting collaborative tool.

Elizabeth River Tunnels

OUTCOME

When completed, the Elizabeth River Tunnels will:

  • Reduce travel time for the average peak-period round-trip user by about 30 minutes per day
  • Improve road safety by eliminating bi-directional traffic on the existing Midtown Tunnel
  • Encourage the use of public transportation due to more frequent Hampton Roads Transit bus service between Norfolk and Portsmouth
  • Provide greater accessibility to jobs, educational facilities, medical services, shopping and recreational activities
  • Other benefits include: boosting the local economy and creating jobs


SERVICES PROVIDED

  • Design and construction of a two-lane immersed-tube tunnel adjacent to the existing Midtown Tunnel. Its total length—including the boat section walls—is 5,441 feet (1,658 meters).
  • Design and installation of an automated tunnel and excavation monitoring system for the existing Midtown Tunnel. The temporary system allowed extensive 3D finite-element modeling to be conducted to predict potential tunnel movements and stress changes affecting the existing tunnel during construction of the new tunnel.
  • Rehabilitation and upgrade of the existing tunnels to achieve compliance with current National Fire Protection Association fire and life safety standards and improve lighting and signage.
  • Design of an elevated extension, including a new trumpet-style interchange with Interstate 264, a partial diamond interchange with High Street and upgrades to bridge crossings in the Portsmouth downtown area to improve aesthetic and lighting.
  • Design of interchange improvements in Norfolk at Brambleton Avenue/Hampton Boulevard.
  • Design and installation of an ITS for all tunnels as well as a fiber backbone and ITS devices along the MLK Freeway and I-264.
  • Design and installation of a water main installed by horizontal directional drilling (HDD).