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Alaska’s Ketchikan Viaduct Gets Facelift

Wed September 22, 2010 - West Edition
Rebecca Ragain


After concrete repair areas are identified and prepared for patching, workers pump grout into the formwork underneath the bridge deck as the final repair. Grout is pumped into the forms until the grout is forced up and through the drilled vent holes locat
After concrete repair areas are identified and prepared for patching, workers pump grout into the formwork underneath the bridge deck as the final repair. Grout is pumped into the forms until the grout is forced up and through the drilled vent holes locat
After concrete repair areas are identified and prepared for patching, workers pump grout into the formwork underneath the bridge deck as the final repair. Grout is pumped into the forms until the grout is forced up and through the drilled vent holes locat Official Alaska Department of Transportation and Public Facilities photo
Contractor personnel drill vent holes through the Tongass Avenue bridge deck prior to pumping grout into the concrete repair forms. The repair forms are located on the bottom side o

Tourists visiting Alaska know the town of Ketchikan as one of the first northbound stops along the Inside Passage cruise route. Ketchikan is also the transportation hub and government center for the southern part of the Alaska Panhandle.

Whereas the must-see area for out-of-town visitors is historic Creek Street, where old wooden shops overlook the salmon-laden creek, locals spend much of their time traveling the main traffic corridor through town, Tongass Avenue, which becomes Tongass Highway to the north and south.

The Tongass Avenue Viaduct, constructed in the 1950s, is in the midst of receiving much-needed improvements. In February, contractor SECON began the second phase of work to rehabilitate approximately 1,000 ft. (305 m), 23 spans, of the viaduct, which sees average daily traffic of 17,700 vehicles.

The scope of the $7.5-million, federally-funded project involves repairing and rehabilitating spalled and delaminated concrete on both the superstructure and substructure of the viaduct.

In addition, long-term corrosion prevention will be installed in the form of cathodic protection systems, including metalized zinc on the underside of deck panels and deck beams, pre-fabricated zinc jacket systems on existing piles and selected pile caps, and zinc ingot anodes on piles below the tidewater level.

“There are many areas of delaminated concrete and corrosion of the reinforcing steel in the substructure and bridge deck that require reconstruction and repair to avoid load limiting of the structure,” said Alaska Department of Transportation and Public Facilities Chief Communications Officer, Roger Wetherell, in an email.

According to Wetherell, major equipment used for this project consists of the work platform and enclosure, negative air and heating systems, sand blasting and containment equipment, and arc-spray metalizing equipment.

As of early September, nine spans of the viaduct had been rehabilitated, leaving the remaining 14 to be completed by the scheduled end date of mid-March. Thus far, the primary challenge has been scheduling work around the tides, said Wetherell.

This is the final phase of rehabilitation planned for the Tongass Avenue Viaduct. Future improvements will involve the outright replacement of existing viaduct sections wherever practicable.

SECON is currently working on additional Tongass roadway improvements, to the north and south of the Tongass Avenue Viaduct, for the Alaska DOT and PF: a $1.3 million job, awarded in January, to replace aging guardrails on South Tongass Highway; and a $8.7 million contract, awarded in April, to reconstruct approximately two miles of North Tongass Highway.

Juneau-based SECON is a grading, paving, drainage, water and sewer contractor and a subsidiary of Colaska, which was formed in 1999 when French transportation construction giant, Colas SA, bought SECON. Other Colaska subsidiaries include Exclusive Paving, a heavy civil, utility, and highway construction firm in Fairbanks, and AGGPRO, providing concrete and aggregate in Juneau and Anchorage.