Military necessity has often driven engineers and construction teams to innovate. This was certainly the case when the U.S. military confronted the challenges of building in Arctic environments after it decided in the 1950s to extend the Distant Early Warning Line of radar bases eastward across Greenland.

The U.S. established several air bases there during World War II, but their strategic value escalated during the Cold War, with proximity to the Soviet Union. Much activity occurred at Thule Air Base, the northernmost outpost, which was massively expanded in 1951 when a U.S. Navy armada delivered a 12,000-person contingent and 300,000 tons of cargo in a secret operation.

ENR Editor-in-Chief Waldo Bowman visited several Greenland bases in 1957. His resulting cover story sketched out many of the construction challenges and solutions.

Permafrost had to be insulated to avoid damage to foundations when it thawed. About 3 ft of gravel fill was placed to cover it, with a 6-in.-thick concrete pad cast as the underfloor for air ducts. Open at both ends, these allowed cold air flow beneath buildings and insulated permafrost from the heat inside. Precast concrete framing made structures rigid enough to cope with Greenland’s fierce winds. Netherlands-based Schokbeton supplied a novel type of concrete that was denser and stronger. To insulate building walls from heat transfer, they were placed outside the frame.

ENR Editor-in-Chief Waldo Bowman visited the sites of several U.S. military installations in Greenland in 1957, including some remote bases carved directly into the ice itself.
Photo from ENR Archives

Ventilation was another challenge. Moisture from internal vapor pressure froze inside of prefabricated panels during the cold season and melted during thaws, causing “interior rain” inside buildings. To avoid this, exterior aluminum roof panels were replaced with plywood and tar paper held down by wood battens, allowing the roof to breathe externally and dissipate vapor.

Thule air base, sited on a gravelly coastal strip in northwestern Greenland facing the edge of the ice sheet that covers 80% of the island and is up to two miles thick in places, hosted a fleet of strategic bombers. The ice sheet’s edge had ice cliffs several hundred feet high, with chunks falling off and waterfalls of meltwater cascading in the summer.

Bowman also visited the most remote U.S. base, an unnamed weather and warning station 250 miles from Thule in the center of the ice sheet. Operated by the U.S. Army 1st Engineer Arctic Task Force, the base mission was to study the ice itself and determine how to establish bases in such an alien, windswept environment. Bowman described camp buildings made of 18-ft-dia corrugated pipe sections buried in snow, accessible by ramps or vertical shafts. He also described how a Swiss-made snow plow dug trenches to be roofed over.

These activities climaxed in 1959 with construction of Camp Century, located on the ice cap 150 miles east of Thule. Built during one short summer, it consisted of a network of 23 interconnected tunnels totaling 9,800 ft to support a contingent of up to 200 soldiers. The cut-and-cover tunnels were excavated snow trenches, roofed over with corrugated metal and covered with snow. The site, powered by a small nuclear reactor, appeared to be a scientific research base. But it actually was a preliminary camp for Project Iceworm, a planned network of nuclear missile launch sites that could survive a first strike. Within several years, movement of the snow compressed the tunnels, forcing the base to be abandoned in 1967. No missiles were ever placed in Greenland.

At both Camp Century and the unnamed research base, the ice cap was drilled to obtain continuous core samples, with various scientific instruments lowered into the holes to take readings. In 1966, a team at Camp Century successfully drilled 4,551 ft, probably the deepest ice core sampling at the time. The samples now are stored at the National Science Foundation Ice Core Facility in Lakewood, Colo., and continue to provide valuable data to scientists studying how the climate changes over time, since the cores contain a long history of greenhouse gas concentrations and volcanic and solar activity.

A Record Wooden Structure

Another example of military necessity driving a precedent-setting project was the Air Force Lab Transmission-Line Aircraft Simulator, or ATLAS-1, a giant wooden structure better known as Trestle, which was located at Sandia National Laboratories near Kirtland Air Force Base in New Mexico. It was part of an apparatus to test the ability of military aircraft electronics systems to resist electromagnetic pulses generated by nuclear weapon detonations. The structure had a 386-ft-long, 51-ft-wide ramp leading to a 200-ft-squared platform, 125 ft high, inside a natural depression. Wood was used for construction since metal would direct pulses away from planes, and its height prevented ground interference.

Douglas fir and Southern yellow pine were chosen for their tensile strength and weather resistance, with 410,000 pieces of lumber glue-laminated into 15,000 members and joined with bolts. Quality control was strict. “Each piece of lumber is dried at the plant and inspected for moisture content before being planed and treated,” a 1977 ENR article said. Some members were 126 ft long and 52.5 in. deep and contained 10,000 board-ft of lumber. “As an example of the strict tolerances, the biggest members could not deviate more than 1⁄4 in. in any dimension,” ENR said.

From 1980 to 1990, military aircraft were towed onto the trestle deck and bombarded with electromagnetic pulses, but test results are classified. Testing ended in 1991 due to increased availability of far cheaper computer simulations. Trestle, which still stands, is considered the world’s largest wooden structure at 6.5 million board-ft.

Fallout Shelter Construction

The Cold War threat of nuclear weapons led to public and government debate over the issue of fallout shelters. Unlike blast shelters that were designed to withstand the force of a nuclear detonation, fallout shelters were intended simply to limit exposure to radioactive fallout that would later blanket the area.

Probably the first ENR editorial on the subject, titled “Why Build Large Bomb Shelters?” was written in 1951. “A study of the plans being proposed by municipal officials for protecting urban populations against bombs should make it clear that only relatively few people can be accommodated in community-owned facilities,” it said. “Consequently … it does not seem logical to build a few large bomb shelters with public money.”

The editorial said even if large shelters could be built, “only a few people would ever get to use them. In the estimated time available between the first warning of an impending air raid and the dropping of bombs—8 to 15 minutes—it would be impossible to empty large office or apartment buildings and transport tenants.… Probably, panic would kill more people than bombs, if this were tried.”

These and other limitations led Congress to task the Civilian Defense Administration with guiding local governments and providing technical information, but not to engage in actual shelter building. ENR reported In 1956 that the agency planned to survey existing structures that could serve as fallout shelters, research ways to build fallout protection into existing buildings and incorporate shelters into new federal buildings, representing only a 2% additional cost.