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Whittier Access Project - Tunnel Segment

Project type:

Tunnels/tunnel systems


Lead design for design-build

Construction cost:

$60 million

Awards won:

2001 Schreyer Award for Civil Engineering (Canada's highest award for engineering excellence), Canadian Consulting Engineers

2001 Award of Merit, ASCE

2001 Grand Award, American Consulting Engineers Council

2001 Best Project (public sector over $15 million), Design/Build Institute of America

2001 Outstanding Engineering Award, FW Dodge

2000 National Winner - Globe Award, American Road & Transportation Builders Association

2000 Project (public sector over $15 million), Portland Cement Association

Alaska Department of Transportation & Public Facilities / Whittier, Alaska

The Whittier Access Project – Tunnel Segment is the conversion of a 13,100-foot single-track hard-rock rail tunnel to a dual-use rail/highway tunnel, forming part of the highway connecting the port of Whittier to the Seward Highway and the commercial heart of Alaska.

The converted tunnel is the longest road tunnel in North America. Its dual function is accomplished with a precast concrete roadway surface with integral rails and a sophisticated traffic control system that allows both control of the single-lane highway traffic flow direction as well as the safe operation of train traffic.

As lead designer for the design-build project, Mott MacDonald's design services covered the following:

  • Roadway, including subgrade & drainage
  • Ventilation system, both normal operation & emergency
  • Emergency evacuation
  • Tunnel & site lighting
  • Traffic control system
  • Train signal system
  • Vehicle staging areas
  • Toll plaza & ancillary structures
  • Quality Control services (provided on-site during construction)

This landmark project boasts several “firsts,” including these:

  • Longest highway tunnel in North America (13,300 feet/2.5 miles)
  • First combined-use rail-highway use tunnel in North America
  • First tunnel to use a ventilation system that combines jet & portal fans in US
  • First tunnel with a unique traffic-control system that regulates rail & vehicular traffic
  • First tunnel designed to operate in temperatures down to –40°F, and winds up to 150 mph & portal buildings able to withstand avalanches
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