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Whittier Access Project
Whittier, Alaska
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Whittier Access Project
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Interior of the Whittier Tunnel showing
the roadway pavement and track rails. |
During the military buildup of World War II, the U.S. Army Corps
of Engineers built a railroad spur to Whittier, Alaska, a port town
on Prince William Sound. The 15-mile (24 km) track connected Whittier
to the mainline of the Alaska Railroad, which serves the state’s
major population centers. After World War II, Whittier and the surrounding
Chugach National Forest began to attract recreationists and tourists,
and access was only by boat, plane, or train. The Whittier Access
Project has now changed that, however, by connecting Whittier with
Alaska’s highway system.
The Tunnel Segment Conversion Project, part of the larger project,
called for an innovative reconstruction of the 2.5-mile (4.0-km)
long railroad tunnel, creating the longest highway-rail crossing
in the world. The dual-use facility allows alternating one-way automobile
traffic, but also gives Alaska Railroad trains the right-of-way.
Drivers arrive at a toll plaza and staging area at one of the tunnels
and travel through single-file one way at a time.
 The
tunnel flooring system provides for dual use by automobile/truck
traffic and train traffic. The flooring system consists of 8-foot
(2.4-m) wide x 7.5-foot (2.3-m) long x 14-inch (360-mm) thick precast
concrete grade crossing modules—Startrack II—placed
end to end for a total of 14,000 ft (4270 m). The modules are designed
to support both railroad and highway loads, with the rails set in
a premolded trough that allows the top of the rails to be flush
with the top of the pavement for smooth driving and safety. Once
the rails were installed, the troughs were filled, forming flangeways
for train wheels. The shoulders remaining on both sides of the precast
modules were then filled with cast-in-place concrete, creating a
115-foot (3.5-m) wide driving lane.
Installation of the modules occurred during extended work windows
of 4 to 6 days. There is also a complex tunnel ventilation system
to accommodate normal and emergency operations, and a traffic control
system to maximize the traffic carrying capacity for both trains
and vehicles. The $32-million tunnel project was constructed using
the design/build process to meet the overall project’s fast-track
schedule.
Project Credits
Owner: Alaska Department of Transportation and Public Facilities,
Juneau, AK
Owner’s Representative: HDR Inc., Anchorage, AK
Design/Build Contractor: Kiewit Pacific, Anchorage, AK
Crossing Manufacturer: Oldcastle/Utility Vault Co., Fontana, CA
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