EPS Insulation Helps Alaska DOT Keep Crucial, Remote Road Open

By Daryl Sobek

Stretching 415 miles from near Fairbanks, Alaska, to the Prudhoe Bay oil fields on the Arctic Ocean, the Dalton Highway is one of America’s most remote roads. Originally called the North Slope Haul Road, the highway was built to support construction of the Trans-Alaska Pipeline. Today it continues to serve oil field traffic and is a crucial lifeline for Alaska communities above the Arctic Circle. The road faces such severe weather that it was featured on several seasons of the reality TV show “Ice Road Truckers.”

To keep the Dalton Highway operating year-around, the Alaska Dept. of Transportation (DOT) hired Cruz Construction to upgrade a 50-mile segment of the road south from Prudhoe Bay. A key part of the project is installing insulation in the roadbed to keep the permafrost frozen and to stabilize the road. The insulation does double duty:

  1. Banking cold within the roadbed in winter to keep the permafrost frozen in summer, for a more stable and durable road
  2. Providing lightweight structural infill to raise the roadbed above the flood level, without over-compressing the underlying soils

The project team is on schedule to finish this summer, and will be paving that same portion of the road after the last of the foam installed.

The Dalton Highway runs for 415 miles between Fairbanks, Alaska, and Prudhoe Bay.

The project team designed the road in accordance with the strenuous specifications of AASHTO M230 – the American Association of State Highway and Transportation Officials “Standard Specification for Expanded and Extruded Foam Board (Polystyrene).” Traditionally, the only product that could meet this standard was extruded polystyrene (XPS) foam board, due to the standard’s thermal values, water absorption and compression values. However, because the Insulfoam Anchorage plant has specialized manufacturing equipment, the company was able to produce expanded polystyrene (EPS) boards that meet AASHTO M230.

Cruz construction is installing two layers of 2-inch-thick InsulFoam® 40 EPS as part of the road base, under a gravel road surface – with project completion scheduled for this year. InsulFoam 40 is a high-performance insulation consisting of a superior closed-cell, lightweight and resilient EPS, manufactured in a plank mold.

To supply the massive quantity of insulation needed for the Dalton Highway, Insulfoam’s Anchorage plant as of fall 2018 had produced 4 million cubic feet of InsulFoam 40 EPS (picture a football field stacked about 70 feet high with insulation). This required the plant to solve a range of production challenges needed to operate 24/7 for three years, while still also meeting other local demands for insulation products. Specifically, the plant ramped up production to supply three-and-a-half 52-foot long flatbed trucks of EPS every day to meet the Dalton Highway construction schedule, and worked with the contractor to ship the materials more than 500 miles to the jobsite.


Daryl Sobek is the General Manager of Insulfoam’s Anchorage, Alaska location and oversees all sales and operations of the Anchorage facility.

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