In 1942, soldiers in the Yukon Territory placed open tin cans filled with gasoline underneath the transmissions of 17-ton Caterpillar D8 bulldozers and lit them on fire. That was the official maintenance procedure. If the flame went out overnight, the lubricant inside the gearbox froze solid, and a machine worth more than a million dollars in today’s money became a 17-ton paperweight in the snow. Between March and November of that year, the United States Army sent over 900 tracked tractors, 374 blade graders, and more than 5,000 trucks into the Canadian wilderness to build 1,422 miles of road through territory that had never been surveyed.

They built a suspension bridge over the Liard River using steel salvaged from the Tacoma Narrows Bridge, the one the whole world watched collapse on camera in 1940. That steel is still holding traffic today. The road cost $500 million. Ninety-nine percent of wartime supplies to Alaska still went by ship.

This is the story of the machines that built the Alaska Highway and why the men who drove them said the equipment broke before they did. December 7th, 1941, Pearl Harbor, Hawaii. The Japanese attack killed 2,403 Americans and pulled the United States into a war already burning across two continents. But the immediate military problem for the War Department was not Europe.

It was Alaska. The territory sat exposed on the northern Pacific Rim with almost no overland supply route from the continental United States. Every pound of fuel, food, and ammunition reaching Alaska traveled by ship from Seattle or San Francisco through waters that Japanese submarines were already patrolling. On February 11th, 1942, President Franklin Roosevelt authorized construction of a highway to Alaska.

The decision came without any reliable survey of the ground it would cross. The War Department had five proposed routes on the table. Route A hugged the Pacific coast and was backed by Alaska’s territorial governor Ernest Gruening, but it sat within range of Japanese naval and air attack. Route B paralleled the Rocky Mountains, but crossed avalanche country with brutal snow loads.

Route D connected to the Norman Wells oil fields, but added 300 extra miles of distance. The route that won was a fifth option that nobody had fully surveyed. It followed the Northwest Staging Route, a chain of airfields built to ferry American Lend-Lease aircraft to the Soviet Union through Edmonton, Grande Prairie, Fort St. John, Fort Nelson, Watson Lake, Whitehorse, and on to Fairbanks.

The airfield chain solved the resupply problem. It had fuel depots. It had landing strips for emergency cargo drops. What it did not have was a road, a topographic survey, or any reliable estimate of what the terrain actually looked like at ground level.

Engineers and surveyors would work the line out as the bulldozers advanced. On some sections, the survey crew was only ten miles ahead of the lead D8. They climbed trees, took compass bearings on distant landmarks, and blazed a line through wilderness on that azimuth, abandoning conventional theodolite traverses for speed. By May 1942, survey parties were still being supplied by canoe, floatplane, and packhorse.

Governor Gruening, whose coastal Route A had been rejected, was publicly irritated. He continued to push for his preferred alignment as late as 1947. The army ignored him. Six months into the project, Japan made the threat personal.

On June 3rd, 1942, Japanese aircraft bombed Dutch Harbor in the Aleutian Islands, killing 43 American servicemen and wounding 50 more. Three days later, on June 6th, Japanese forces occupied Kiska Island. The day after that, they took Attu. For the first and only time during the Second World War, enemy soldiers held American soil.

The Japanese were now closer to the mainland than the army was to Alaska, and only about 150 miles of pioneer road existed at the time of the invasion. The threat unleashed the round-the-clock pace and the decision to deploy every available engineer regiment, including the three African-American regiments that Secretary of War Henry Stimson had initially refused to send north. The army deployed seven engineer regiments totaling 394 officers and 10,765 enlisted men: the 18th, 35th, 93rd, 95th, 97th, 340th, and 341st Engineers. Three of those regiments, the 93rd, 95th, and 97th, were African-American general service regiments.

They composed roughly a third of the total force, about 3,700 men. Stimson had initially refused to deploy black soldiers to the far north, arguing incorrectly that African-Americans could not withstand Arctic conditions. He reversed the decision in mid-June 1942 when manpower pressure left him no choice. The black regiments were given the oldest surplus equipment, the worst supply lines, and the most brutal terrain assignments.

In addition to the military regiments, approximately 7,500 civilian workers from the Public Roads Administration joined the project during 1942. The job description they received was blunt:

“Men hired for this job will be required to work and live under the most extreme conditions imaginable. Temperatures will range from 90° above zero to 70° below zero. Men will have to fight swamps, rivers, ice, and cold.

Mosquitoes, flies, and gnats will not only be annoying, but will cause bodily harm. If you are not prepared to work under these and similar conditions, do not apply. ”

That was not propaganda. That was the job description.

The official War Department equipment inventory for the Alaska Highway reads like a mobilization order for an entire nation’s construction fleet: 174 steam shovels, 374 blade graders, 904 tracked tractors, more than 5,000 trucks, plus bulldozers, snow plows, cranes, generators, draglines, and pull scrapers. The 904 tracked tractors were overwhelmingly Caterpillar, but not exclusively. Allis-Chalmers M and S series crawlers appeared in contractor inventories, particularly after the Public Roads Administration brought its own fleet north in 1943. International Harvester TD-9, TD-14, and TD-18 crawlers appear in numerous period photographs, particularly with civilian contractors like Dawel Construction.

Even Cletrac machines from the Cleveland Tractor Company showed up in military equipment surveys as alternates where Caterpillars were unavailable. The blade graders were primarily Adams and Galion units, since Caterpillar’s first motor grader, the number 11 Auto Patrol, was in production but not yet the dominant brand. The 174 steam shovels were largely Bucyrus-Erie 50-B and 65-B machines and Marion 4120 shovels, most of them running gasoline or diesel power despite the official term “steam shovel” still appearing in army paperwork. A Caterpillar engineer turned soldier named Tom, documented in Caterpillar’s own corporate history of the project, was a motor officer responsible for keeping his platoon’s machines running.

His complement was 18 D8 bulldozers and 20 D4 tractors, more than a million dollars worth of iron, which in today’s money would be roughly 17 million dollars. And that was one platoon in one regiment. The backbone of the entire project was the Caterpillar D8 in two distinct production series. The D8 1H, built from 1935 to 1941, was the first true D8 after the short-lived RD85E, of which only 33 were ever produced.

The D8 1H ran a six-cylinder naturally aspirated Caterpillar D13000 diesel engine producing 110 flywheel horsepower. It used a six-speed forward, single reverse manual transmission with a manual dry clutch. Top speed was about 5 and a half miles per hour in sixth gear. Bare weight was approximately 16 and a half tons.

When America entered the war, the War Production Board demanded simpler, faster-built machines with fewer optional extras. Caterpillar responded with the D8 8R, the wartime austerity tractor. It used the same D13000 block, but a more efficient fuel pump that pushed output to 130 horsepower. Bare weight rose to roughly 17 tons.

About 9,900 8R series machines were built between 1941 and January 1946, and the vast majority went directly to the armed forces. The last 8R rolled out of Peoria, Illinois bearing serial number 8R9999. Many of the Cats filmed pushing trees on the Alaska Highway in the summer and fall of 1942 were 8R machines delivered straight from the Peoria factory to the railhead at Dawson Creek, British Columbia. Motor officer Tom put it simply: “Generally, we were familiar with the equipment, right at home, in fact.

Men pushed the machines to their utmost power, and the machines responded. ”

Supporting the D8 tractors were the smaller Caterpillar D4 and D7 tractors. The D4 weighed about 7 tons and produced roughly 45 horsepower. The D7 sat in between at 10 to 12 tons.

A widely circulated Army Signal Corps photograph from the project shows a D4 dragging a scratch-built log grader across a freshly cut grade because the regiment had outpaced its supply of factory blade graders, and the operator improvised from locally felled timber. The D7 tractors handled the secondary earthmoving, pulling LeTourneau carryall scrapers on shorter runs and trimming road shoulders after the D8 tractors had cleared the corridor. Multiply Tom’s single platoon by seven regiments, and the total number of Caterpillar tractors simultaneously operating on the Alaska Highway exceeded several hundred machines at peak construction. But the Caterpillar D8 was only half the story.

The bulldozer blade was not a Caterpillar product. In 1942, Caterpillar built the tractor. The blade, the scraper, and the angle dozer attachment were sourced from outside vendors, and two companies dominated the Alaska Highway. LaPlant-Choate of Cedar Rapids, Iowa supplied the cable-operated angle dozer blades on most of the D8 tractors.

The Detroit Public Library holds a Caterpillar publicity photograph dated May 1943 with a handwritten caption identifying a D8 with a LaPlant-Choate bulldozer shaping the road over a timber culvert on the Alaska Highway. These blades worked on steel cable. A cable ran from a friction clutch power take-off drum on the front of the tractor to the blade. The operator raised and lowered the blade by engaging and releasing the clutch.

There was no hydraulic cylinder, no hydraulic pump, no hydraulic lines. R. G. LeTourneau of Peoria, Illinois supplied the power control units, the carryall pull scrapers in the LP, LS, FP, and W series, and additional angle dozer blades.

According to LeTourneau’s own corporate records, more than half of the 1,500-mile Alaska Highway in Canada was built using LeTourneau equipment. Hydraulic dozer controls would not become standard on Caterpillar production machines until the post-war D8H of 1958. Every single blade on the Alaska Highway was pre-hydraulic. The cold weather operation of these machines is one of the most overlooked engineering survival stories of the entire war.

The D13000 engine used a small auxiliary gasoline starting motor called a pony motor to crank the main diesel and warm it up. In temperatures that dropped to minus 40°F, minus 50°F, and on documented occasions minus 70°F, a cold diesel engine simply would not start. So the engines never shut down. Motor officer Tom stated it directly: “Cat seldom cooled their engines unless laid up for some repair.

” In such cases, he had to see they ran again. D13000 diesels ran 24 hours a day for weeks at a time. Idling at low temperatures caused severe carbon fouling and oil dilution, but the men accepted that cost rather than risk a dead start in the morning. For the transmissions and axle housings, the men used the method that opened this story.

They filled empty soup cans with gasoline, placed them underneath the gearbox, and lit them. An open flame underneath a 17-ton oil bath transmission with no fire suppression equipment, no safety protocol, and no regulation. In 1942, that was the standard field procedure. Fuel was another constant crisis.

The D13000 was a true compression ignition diesel, and the army-grade diesel fuel was often not winterized for the temperatures it actually encountered. Fuel gelling at the filter was a persistent failure mode. The Canol pipeline project, built concurrently from Norman Wells in the Northwest Territories to a refinery at Whitehorse, was supposed to solve the fuel problem. It was a colossal failure.

The pipeline produced only 3,000 barrels a day, far below requirement, and was scrapped shortly after completion. Senator Harry Truman’s investigation of the Canol boondoggle gave him the national profile that led to the vice presidency in 1944. Beyond fuel, the equipment suffered in ways modern operators would find hard to believe. Track pin bushings galled out in the cold.

The 8R manual dry clutch became brittle and cracked. Axles snapped in seconds when trucks drove through partially frozen Yukon streams because ice locked the wheels before the driver could react. If the truck stopped moving for even a few seconds after crossing water, the axle broke. The soldiers called it the oil can highway.

Empty fuel and oil drums were so abundant along the route, left where used, never picked up, that the road was literally marked by them. The construction method the army developed was called the train system. Heavy D8 bulldozers led the advance in formation, knocking down and uprooting trees in a corridor 50 to 90 feet wide. Motor officer Tom described the pace: “Through wooded expanses, our tractors pushed and uprooted millions of board feet of jackpine and spruce.

Trees were converted readily to our needs for timber for our bridges and our corduroy roads. ”

Secondary D8 tractors and D7 tractors pushed the debris to the sides. D4 tractors and corduroy crews followed, laying spruce and jackpine logs perpendicular to the road center line across the worst muskeg and swamp. Bridge and culvert crews came next, operating portable sawmills that the regiments carried to cut stave pipe culverts and timber bridge decks from the freshly felled trees.

Finally, LeTourneau carryall pull scrapers behind D7 and D8 tractors moved gravel from the nearest borrow pit, while Adams and Galion blade graders shaped the running surface. Where the train system was impractical, the regiment switched to a leapfrog method, with each crew responsible for a segment 5 to 10 miles long, jumping to the front when finished. At peak pace, the combined force pushed 400 miles of new road in July 1942 alone. That works out to roughly 13 miles per day across all active fronts.

The men on the corduroy crews, often the African-American regiments who were initially denied power tools, felled trees with double-bit axes, crosscut saws, and one-man bow saws called Swede saws. They laid the logs by hand. The D4 tractors pushed brush into the low spots. The D8 tractors drove over the top.

And on the worst muskeg, the road sank anyway. Muskeg is a spongy organic bog that covers vast stretches of northern Canada. It swallowed equipment whole. The permafrost beneath the surface stayed frozen only as long as the vegetation insulating it remained intact.

When the bulldozers stripped the moss and trees, the permafrost started to thaw. The road surface liquefied. Bulldozers that had been running on solid ground in November found themselves sinking into bottomless mud by May. The following spring, roughly 100 miles of highway between Burwash Landing and Koidern in the Yukon Territory became nearly impassable as the road surface melted from underneath.

D8 tractors that had built the road now had to rebuild it, dragging in fresh corduroy logs and gravel fill over sections that had been passable just months earlier. The rebuild required massive quantities of fresh brush, timber, and 2-foot thick crushed gravel caps laid over the original corduroy. On some of the worst muskeg sections, entire stretches of pioneer road simply disappeared into the bog. Public Roads Administration contractors in 1943 had to cut entirely new alignments around them rather than attempt repair.

Ken Rust, historian of the 18th Engineer Regiment, described the equipment toll in terms that defined the entire project: “Men suffered, but held up better than equipment. Trucks with bent frames and beds and distorted springs moved crabwise up the road. Some trucks broke in half and were left beside the road as derelicts. ”

The supply of spare parts could not keep up with the demand.

Wrecked vehicles became a common sight on the sides of the lengthening road. General William Hoge said the mosquitoes were worse than the machines: “You had to eat with your head net on. If you raise the head net, by the time you got food on the spoon up to your mouth, it would be covered with mosquitoes. ”

The worst single equipment disaster of the entire project happened at Charlie Lake in British Columbia on May 14th, 1942.

That morning, Major John Turvey of the 341st Engineer Regiment supervised the loading of a three-pontoon raft that had been built the previous day under Lieutenant John Langendorf of the 74th Engineer Company. The cargo was a radio command car, a bulldozer, drums of oil, and other supplies. Seventeen men were aboard. The raft pushed off from the south end of Charlie Lake into 1-foot chop.

By midday, the water had roughened. The overloaded raft was swamped and sank. A homesteader and fur trapper named Gustav Hedin launched his 14-foot rowboat from the shore, reached the survivors in roughly 15 minutes, and made three round trips to bring five men back. Twelve soldiers of the 341st drowned, including Private First Class Paul Laws.

The final body was not recovered until June 9th. Hedin received a medal from the Humane Society of Canada. A memorial with 12 stainless steel posts was unveiled at the site in 2008. The bulldozer went to the bottom of Charlie Lake and stayed there.

This remains the only confirmed total loss machinery sinking documented during the entire construction. Brigadier General William Hoge, the original commanding general of the entire highway project, was relieved of his command in September 1942 by Lieutenant General Brehon Somervell, the Army’s Chief of Logistics. Somervell, nicknamed “Dynamite in a Tiffany box,” had conducted a four-day inspection in August and concluded that Hoge’s troops were unprepared for the approaching winter. Hoge claimed afterward that Somervell fired him to settle a personal score from the 1930s, not on engineering grounds.

Brigadier General James O’Connor replaced Hoge in September and presided over the November dedication two months later. The general who took credit for finishing the Alaska Highway had commanded the project for only its final two months. The Sikanni Chief River Bridge became the most celebrated construction feat of the entire project, and it was built by the regiment that had been given the worst equipment. The 95th Engineer Regiment was an all-black unit.

When they reached the Sikanni Chief Crossing in August 1942, the standard Army estimate for a 300-foot timber bridge was about seven days. The men of the 95th bet a month’s pay against the white officers that they could do it faster. Their master sergeant put it simply: “We cannot afford to lose our own personal pride by slipping up. ”

They built the bridge in 84 hours, three and a half days, about half the time the army considered standard for a structure of that scale.

The permanent replacement, three 140-foot Douglas fir deck trusses with hardware pre-cut at Vancouver and Portland, opened on April 25th, 1943. It was the first large permanent structure completed on the entire Alaska Highway. The original 1942 timber bridge was destroyed by arson on July 10th, 1992. Then came the moment that closed the road.

On October 25th, 1942, two Caterpillar D8 bulldozers pushed through the timber from opposite directions near Beaver Creek in the Yukon Territory and met bumper to bumper. The operator coming from the south was Corporal Refines Sims, Jr. of the 97th Engineer Regiment out of Philadelphia. The operator coming from the north was Private Alfred Jalufka of the 18th Engineers out of Kennedy, Texas.

Sims was black. Jalufka was white. This was six years before President Truman signed Executive Order 9981, officially desegregating the United States Armed Forces. The photograph of the two men shaking hands over a cable-controlled bulldozer blade that had no hydraulics and no power steering became one of the most reproduced civil rights and machinery images of the Second World War.

Sims won the unofficial race between the two regiments. The image was captured by Harold Richardson of Engineering News Record. Three days later, on October 28th, 1942, the pioneer road was declared complete along its full length. While the bulldozers were closing the last gap in the pioneer road, a separate team of engineers was starting the most ambitious bridge of the entire project.

The Peace River Suspension Bridge at Mile 35 was contracted to John A. Roebling’s Sons company, the firm that built the Brooklyn Bridge. On the Alaska Highway, Roebling’s engineers had 9 months, not 14 years. Construction began in November 1942 in temperatures that reached minus 60° Fahrenheit.

The concrete and approach work was performed by the Dufferin Paving Company of Toronto. The finished bridge measured 2,130 feet in total length with a main span of 930 feet, two 200-foot suspension towers, and a 24-foot wide concrete deck. It was the longest suspension bridge in the British Empire at the time. The bridge opened in August 1943 and served for 14 years until it collapsed on October 16th, 1957 when a landslide undermined the north abutment.

The Cretaceous Shaftsbury Formation shale beneath the gravity anchor had weathered into high plasticity clay over those 14 years. The same geological formation that held the anchor in 1943 dissolved it by 1957. But the bridge that did not collapse, the one still carrying traffic today, tells an even more surprising story. The Lower Liard River Suspension Bridge was built in 1943 using steel salvaged from the Tacoma Narrows Bridge.

Galloping Gertie, the bridge that twisted itself apart in a 42 mph wind on November 7th, 1940, produced some of the most famous engineering failure footage ever recorded. The army salvaged the wreckage, shipped it north, and used it to build a permanent crossing for a highway that was supposed to be temporary. The Liard River Bridge is the only original suspension bridge still standing on the Alaska Highway. It carries traffic on recycled steel from the most famous bridge collapse in American history.

On November 20th, 1942, a small group of officials gathered at Soldier’s Summit near Kluane Lake in the Yukon Territory for the formal dedication of the Alaska Highway. The outdoor temperature was minus 35°F. The ceremony was broadcast by radio. General James O’Connor, who had commanded the project for just two months, speculated that the road might become an American saga ranking with the epics of Fremont and Lewis and Clark.

The road he was dedicating was barely functional. It was 12 feet wide with steep grades, poor surfacing, switchbacks to gain and descend hills, and almost no guardrails. In many places, the road was so narrow that two trucks could not pass each other without one backing up to a wider spot. The bridges, which had progressed during 1942 from pontoon rafts to temporary log spans, were already failing under their own weight.

One 272-foot timber bridge was completely swallowed by 15-foot thick spring ice in early 1943 and had to be rebuilt from nothing. Several other bridges survived a single winter and then collapsed under the spring thaw loads. The pioneer road was not open to civilian traffic until 1948, six years after the dedication ceremony. The soldiers who had built it knew exactly what they had created.

A sergeant poet attached to Stimson’s office captured the mood in verse that circulated through the regiments:

“The Alaska Highway winding in and winding out
fills my mind with serious doubt
as to whether the lout who planned this route
was going to hell or coming out. ”

A fur trader who watched the construction described the transformation: “We were taking goods into the north by horse and dog sleds, the way our fathers and grandfathers had done, when we met a great fleet of trucks as far as the eye could see. Time moved ahead more in a few minutes than it had in a whole lifetime. Like the snap of your fingers, we changed from the old to the new.

”

The real machine story of the Alaska Highway did not end in November 1942. It started in 1943. The Public Roads Administration took over the project and launched the largest civilian construction mobilization in northern North America. By mid-July 1943, 81 contractors were on the job, employing roughly 15,950 civilian workers.

The PRA brought 6,000 units of heavy equipment north, including scrapers, power shovels, elevating graders, trucks, motor graders, gravel crushing plants, and portable sawmills. They widened the road from 12 feet to 24 feet with 6-foot shoulders. They dropped the maximum grade from 10% to 7%. They replaced corduroy with 2-foot thick crushed stone and gravel.

They cut 200 miles from the total distance by straightening curves and abandoning the worst pioneer road segments, including the Trutch Mountain summit at 4,212 feet. They rebuilt five permanent steel bridges in Alaska territory alone at the Tanana, Tok, Robertson, Johnson, and Gulkana River crossings. They ran two 10-hour shifts a day from mid-July to the end of October 1943. The PRA reconstruction cost $135 million, roughly equivalent to $1.

7 billion in today’s money. The original pioneer road had cost $19. 7 million. The PRA program compressed a comparable volume of earthmoving into 4 months in the subarctic with pre-hydraulic equipment that was already battle-worn from the 1942 pioneer push.

The total cost of the Alaska Highway, including the pioneer road, the PRA reconstruction, the related Canol pipeline, and the Northwest staging route improvements, reached approximately $500 million. In today’s money, that figure exceeds $6 billion. It was the most expensive single construction project of the Second World War. And after all of that, 99% of wartime supplies reaching Alaska continued to travel by sea from San Francisco, Seattle, and Prince Rupert.

The highway that was built with such brutal urgency to address a Japanese invasion threat was militarily redundant before the dedication ceremony took place. Japan evacuated Kiska quietly in August 1943, slipping away in fog before an Allied invasion force of 34,000 troops landed on an empty island. The United States retook Attu by force in May 1943 in a brutal three-week battle that cost 549 American dead and over 1,000 wounded. The Japanese garrison of roughly 2,600 soldiers fought almost to the last man.

The strategic threat that had justified the entire $500 million highway project was eliminated within months of the road’s completion. The road remained. The machines that built it did not. When the Public Roads Administration released its final contractors in October 1943 and the United States Army transferred control of the Canadian section to the Canadian Army’s Northwest Highway System on April 1st, 1946, the surplus equipment was largely abandoned in place or sold off to Pacific Northwest scrap dealers who had been starved of new iron during the war.

Some of the better preserved D8s and D7s were bought by Canadian logging operators who ran them for another decade in the British Columbia interior. Others were simply left where they had broken down. The economics were simple. Shipping a dead 17-ton tractor out of the Yukon on a gravel road cost more than the machine was worth.

Period accounts and current highway travelers note that rusted out World War II vintage vehicles, abandoned trucks, dead bulldozers, and at least one complete LeTourneau land train near Fairbanks still sit along the route. Fort St. John has a small collection of original equipment at its local museum. The Watson Lake Signpost Forest, founded by a homesick injured G.

I. named Carl Lindley in 1942, preserves a small collection of original 1940s road building equipment beside more than 100,000 signs planted by soldiers and travelers over 84 years. The men who built the Alaska Highway left behind something that the standard military history rarely mentions. They left behind a graveyard of pre-hydraulic iron.

Caterpillar D8s with LaPlant-Choate cable angle dozer blades, LeTourneau carryall pull scrapers that moved more than half the earth on the project, Allis-Chalmers crawlers, and International Harvester TD series tractors appear in the period photographs, but rarely in the written histories. Every one of those machines operated on steel cable, friction clutch, and human muscle. Hydraulic controls were still 15 years away. The men who ran them, including the 3,700 black soldiers who composed a third of the total force and built the Sikanni Chief Bridge in 84 hours, held up better than the equipment.

The Alaska Highway is still open. The Liard River Bridge is still standing on steel from the Tacoma Narrows collapse. And the machines that built both have been rusting quietly in the subarctic since 1943, waiting for someone to tell their story.