The $154-million first phase of the Northern Rail Extension in Alaska is the initial step in a multi-year effort to connect the towns of Fairbanks and Delta and the Fort Wainwright and Eielson Air Force Base military sites with Fort Greeley. Phase 1 was the crux of the project because it established a new crossing of the Tanana River near Salcha.

Located 35 miles southeast of Fairbanks, the project involved construction of a 3,300-ft-long structural steel bridge—the longest bridge in the state.

An 11,000-ft levee was also built along the river’s eastern bank. Kiewit self-performed 95% of the work, including the levee embankment and installation of more than 10,000 ft of 6-ft-dia piles, 19 concrete in-water piers and 80 steel plate girders—each 12 ft tall and 165 ft long—as well as bridge decking.

To enable permanent construction, the team installed temporary cofferdams after each pier installation and removed 1,650 ft of temporary trestle and 1,650 ft of riprap causeway in the river bed.

During preconstruction, the team modified span lengths of the bridge by extending the originally designed 150-ft girders and removing two piers. The steps ultimately saved Alaska Railroad Corp. about $2 million and shaved almost nine weeks from the construction schedule.

The team also took steps to maximize the riprap production yield at the quarry and to minimize costs. As a result, the project cut 83,000 cu yd of riprap needed and $16 million more from project costs.

The project was built primarily in conditions below freezing and all equipment was pretested to establish a low-temperature threshold. Kiewit and HDR worked with HC Redi-Mix to set procedures at its Fairbanks-area batch plant that allowed crews to batch and place concrete at temperatures down to -10 degrees Fahrenheit. About 4,000 cu yd of concrete was placed during the winter months.

The project’s OSHA recordable incident rate was 1.91 with more than 315,000 hours worked. The work was completed on schedule in August 2014.

Northern Rail Extension, Phase 1

Salcha, Alaska

Key Players
Alaska Railroad Corp.
Lead Design Firm HDR Inc.
General Contractor Kiewit Infrastructure West Co.
Structural Engineering Hanson Inc.
Civil Engineering HDR Inc.