The humble culvert—everywhere in our lives—serves an essential function. It carries water from where we don’t want it to where we do. You drive city streets, you walk city sidewalks… You drive or walk over culverts you don’t even noice.
More on the Road Through Yukon
Not remotely humble, culverts sprouted everywhere on the Alaska Highway in 1942. Not the simple corrugated metal pipes that run under your driveway but monstrous timber structures that rival bridges in scale and scope.
In July two companies of the 93rd Engineers crossed the Teslin River to build the road down along the river to Teslin Post. Company C stopped to deal with “Boyd’s Grand Canyon”. By installing a monster culvert. Company B moved on the “Austin Grand Canyon” to do the same.
The road couldn’t simply descend into the canyon then ascend the other side—way too steep. So you bring out the bulldozers and you simply fill the way across the canyon with dirt… Fill it up.
But the canyons existed in the first place because over many, many years a stream had gouged it out of the mountain. And the stream continued to run along its bottom. Fill the canyon with a wall of dirt and you’ve created a dam. Behind the dam the water piles up, especially during the spring melt, until it overflows the dam, destroys it and washes away everything downstream.
Not the desired result.
The soldiers didn’t have corrugated pipe and it wouldn’t have been big enough anyway. So they constructed a rough square tunnel of logs and timbers at the bottom of the canyon for the stream to flow through. They also didn’t necessarily have fasteners to hold the structure together, so they made wooden pegs.
A culvert needed enough height and width, sufficient cross-sectional area, to pass whatever amount of water the stream brought to it. To allow for spring melt, some grew to a size a man could walk through. The length of the culvert depended on the depth of the canyon. The sides of the fill had to slope from a wide base to the width of the roadbed on top; the deeper the fill, the wider the base and the longer the culvert. Culverts ranged in length from 30 to 100 feet or more.
Once they bulldozed and packed dirt on top of the culvert, they had, in effect built a bridge.
The men enjoyed building culverts, a break from the monotony of building featureless rutted road through the woods. And the men of the 93rd got good at it. An outside contractor noted in his logbook that he had watched, impressed, as a black unit near Teslin built a fifteen-foot-wide and forty-foot-long culvert in forty five minutes.
Company B and Company C wouldn’t build the monster culverts for Austin and Boyd canyons in forty-five minutes.