Lifting at Forty Below: Crane Work Through an Alaska Winter

The machine: steel, hydraulics and wire rope

Steel. Structural steel loses toughness as it gets colder, and a shock load on cold steel can crack a component that would have flexed in warmer weather. Crane makers address this in the design and in operating limits: some publish a minimum operating temperature, some offer arctic packages, and some require reduced capacity or slower operation below set temperatures. Your crane's manual and load chart notes are the authority. Avoid sudden starts and stops, dropped loads and jerky swings in deep cold, whatever the chart allows.

Hydraulics. Oil thickens as it cools. The result is sluggish functions, higher pressures and the risk of pump cavitation on start-up. Manufacturers publish warm-up steps tied to temperature. As one example, a National Crane operator manual supplement calls for a warm-up below roughly 40 °F, running functions unloaded until the oil reaches a set temperature, then cycling every function to push cold oil out of the cylinders. Your model may differ, and many fleets in Alaska switch to arctic-grade fluids and use tank or engine heaters.

Wire rope and lubrication. Cold lubricant can stiffen and fail to penetrate the rope. Ice can pack into drum grooves and sheaves, causing poor spooling. Inspect more often in winter and use lubricants the manufacturer approves for low temperatures.

The air: ice, snow, wind and ice fog

Ice and snow on the boom, jib, counterweight and load add weight the load chart does not know about, and frozen snow can shed from height without warning. The crane standard requires following the manufacturer's procedures and makes the competent person responsible for adjusting operations for wind, ice and snow. Clear accumulations before lifting, and remember that ice on a load can change both its weight and its center of gravity.

Wind matters more because cold air is denser. Southcentral Alaska is known for gap winds: the National Weather Service regularly issues high wind warnings for Turnagain Arm and the Anchorage Hillside, where gusts in strong events have been forecast in the 70 to 85 mph range, and Whittier and Portage Valley get their own warnings. Use the wind limits on the crane's chart, check the forecast and the on-site anemometer, and stop when the limit is reached.

Ice fog is the Interior's special problem. In Fairbanks it typically forms around 30 to 35 below zero, mainly from water vapor released by vehicles, heating and power plants, and it thickens as the temperature drops. Dense fog advisories describe visibility down to about a quarter mile. The good news is it is less common than it was: University of Alaska researchers report Fairbanks averaged more than two weeks of ice fog days a year from 1950 to 1980, but only about six a year from 1990 to 2020. When it rolls in, an operator who cannot see the load or the landing area needs a signal person and probably radios.

The ground: frozen, thawing and permafrost

Section 1926.1402 requires ground that is firm, drained and graded enough, with mats or cribbing if needed, to meet the manufacturer's support and level requirements. In Alaska the same pad can pass that test in February and fail it in May.

Frozen ground is strong, but it hides voids, and snow over a soft spot or a culvert looks the same as snow over gravel. During breakup, the top layer thaws while the ground beneath is still frozen, trapping water and leaving a saturated, weak surface. Outriggers that were fine in March can sink in April.

Permafrost adds another layer. The active layer above it freezes and thaws each year, and ice-rich permafrost that thaws can leave the surface far lower than before. Researchers studying communities on the coastal North Slope have measured average ground subsidence of about 2 to 3 inches a year between 2017 and 2022. Work pads are usually built of thick gravel for this reason. Ask the controlling contractor what is under the setup area, use crane mats, and recheck level through the shift.

The light: working in winter darkness

In Fairbanks the sun is up for only about three hours and forty minutes on the winter solstice, and Anchorage and Juneau get only about five to six and a half hours. In Utqiagvik the sun does not rise for roughly two months in midwinter. That means much winter lifting is done under artificial light.

Plan lighting for the load path and the landing area, not just the crane pad. Light the signal person, use illuminated or high-visibility gloves for hand signals, or switch to radios with a dedicated channel. Glare off snow from work lights can blind an operator, so aim lights carefully. Our crane hand signals guide covers the signals themselves.

The people: cold stress and slower hands

Thick gloves make fine control harder, cold hands react slowly, and layers restrict how far a rigger can turn their head to watch a load. Riggers and signal people standing still for long periods are at risk of frostbite and hypothermia. Build in warm-up breaks, rotate crew members, and keep a heated space close to the work.

Fatigue builds faster in cold and dark. Long rotations on the North Slope or at remote mine sites add to it. A crew that is tired, cold and working in poor light makes the kind of small mistakes that cause rigging failures.

A winter pre-lift checklist

• Check the crane manual for minimum operating temperature, capacity reductions and warm-up steps, and confirm the crane is set up for the season.
• Warm the crane up and cycle every function unloaded before the first pick.
• Clear ice and snow from the boom, sheaves, counterweight, outrigger pads and load.
• Inspect wire rope, slings and hardware for ice, stiffness and cracks; check temperature ratings on rigging tags.
• Verify the ground under each outrigger, especially during breakup, and use mats.
• Check wind and visibility; light the work area; set up radios if visibility is poor.
• Brief the crew on cold-stress signs and break schedule.