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Watch for Falling Rock

The canyon of the Fraser River cuts a great ditch through the interior plateau of British Columbia from Prince George to Hope. The northern part, from Prince George to Lillooet, passes through the clay soils of the Cariboo. Here, the river water becomes loaded with clay and takes on a pale brown colour. At Lillooet, the river enters more rocky terrain, the canyon becomes narrower, and the river runs faster in its restricted bed. The best-known area of the Fraser Canyon is from Lytton to Hope, because it is on the Trans-Canada Highway. The Trans-Canada Highway and both major railways enter the Fraser Canyon from the Thompson River canyon at Lytton and all three follow the Fraser Canyon to Hope.

The lower end of the Fraser Canyon is a very unstable place. This is the area where the railways and the highway share the fragile canyon walls. The canyon is a relatively recent development, geologically speaking, and it is still growing with every season—particularly with each spring flood of the river. The walls of the canyon continuously drop rocks, which range from insignificant pebbles to huge sections that peel away from the upper edges of the walls.

As the rainy season progresses through the autumn, the rocks come down in direct proportion to the rainfall. As the rainy autumn season gives way to winter, the wind from the interior brings a sharp drop in temperature and all the rain-filled cracks in the rocks become ice. The newly formed ice can create enough pressure in the cracks to split a clean break through previously solid rock. These wet or cold seasons are always memorable times for the railway and highway workers as they try to keep the rockfalls clear of their routes.

From 1969 to 1972, I worked from the RCMP detachment at Lytton. One evening in the early part of the winter we were called to a motor vehicle incident on the south slope of Jackass Mountain. There were no injuries reported, so we drove out to investigate at a rather relaxed pace. The information we had was that a vehicle had hit some rocks. That side of Jackass Mountain was one of the few three-lane sections of the canyon highway in those days. One lane was for downhill traffic, two for uphill. This allowed most traffic to pass the transport trucks that were very slow on the steep grade.

When we arrived, we found that a pickup truck with a camper had somehow made its way onto the top of a rock in the middle of the highway. The rock was so large that the frame rails of the truck were eight feet above and parallel to the surface of the highway. The truck had relatively light damage to the front bumper and undercarriage.

The driver told us that he had been going down the mountain in total darkness, except for the lights of his vehicle, when his headlights had suddenly picked up a moving mass directly in his path. At first he thought that the movement was a flash flood and that water was rushing across the road. Before he could react, he was into the moving mass and he knew then that it was not water. His truck slammed into something so hard that he and his two passengers were thrown forward into their seatbelts. At the same moment, the truck was lifted straight up with such force that the three were forced downward into the bottom of the seat. They then realized that they were at a full stop. The headlights of the truck were still on and were shining out into empty space. The lights of an approaching vehicle gave them a reference point, and they realized that they were high above the highway surface. The driver checked with his passengers, his wife and daughter, and determined that they were not hurt. He found a flashlight in the cab and began to assess their situation. People from the other vehicle assisted, and the three were able to get down from the stranded truck to the road surface.

The truck’s spare tire was on a bracket on the front bumper. An eight-foot rock had fallen onto the highway and was rolling down the hill away from the truck when they hit it. The spare wheel and tire had gripped the rock and lifted the front of the truck. The truck and the rock had rolled as a unit for a little less than a half a turn of the rock to where they had both stopped. Had the rock rolled another small part of a turn, the truck would have been slammed down onto the highway, causing severe injuries and probably death to its occupants.

The big rock that the truck hit was accompanied by a few hundred cubic yards of rock, most of it in smaller pieces. The two uphill lanes of the highway were completely covered, and smaller fragments covered the downhill lane so that traffic was unable to get through.

A very skilful and well-equipped tow-truck operator was called from Boston Bar. He looked at the truck sitting high on the rock, laughed, and said he had never seen one quite like that. He rigged two lines to the front of the truck and a third line over a triangular frame on the back of his tow truck. He then gently slid the truck forward and put it down on the highway as though it were a toy truck in his hand. He checked the truck for damage and found none that would affect its temporary operation, so the driver and his family drove away toward their destination.

While we were at the scene, more rock was continually falling from the fresh break just above the highway. This was normal after a rockfall. We did not like to be there, but it was considered part of the job hazard. The highway had been closed from the time of the rockfall, and traffic was being re-routed at Spences Bridge and at Hope. We knew we could look forward to a quiet night because the road would not be cleared until heavy equipment was brought in to lift or break up the big rocks. The highway maintenance crew from Lytton brought their small front-end loader and a small dump truck to the scene and started to clean up the pieces that they could handle.

Two men from Lytton had been working around the edges of the rockfall in the two machines for several hours. More rock continued to fall, making them nervous and extremely cautious. The regulations of the Worker’s Compensation Board required that a truck driver be out of the cab of his truck while it was being loaded. The driver at this site would back the little truck into position and then stand alongside it where he could watch and listen for more falling rock. He positioned himself so that he could signal the loader operator if it became necessary to move away.

At about midnight the truck driver was in position, watching the loader operator. The loader was turning away from the truck to go back to the rockfall when the truck driver heard a sound like a dynamite blast. The sound came from the mountainside directly above them. The driver gave a frantic signal to the loader operator to get away and he started to run up the highway away from the rockfall area. The loader operator was facing toward the slide with his machine; he slammed the machine into reverse and threw the throttle wide open. He had just started moving backwards when the first pieces of rock began to hit the machine. Both the truck driver and the machine operator knew they were about to die. A chunk of flying rock hit the bucket of the loader and shoved it sideways, almost causing the machine to roll onto its side. However, the operator was able to steer it enough to prevent a roll-over. The truck driver was able to run much faster than the loader could go in reverse gear, but he wished he had the winged feet of Mercury.

The truck driver was wearing a waist-length leather jacket, and running like he had never run before. He heard the rocks hitting the loader behind him and the overpowering roar of a tremendous force being released. The earth was trembling so hard that both the running man and the machine operator could feel it. The running driver was hit by a blast of wind that picked him off the ground and threw him several yards; he found himself on the ground with his leather jacket inverted over his head and arms as though it were a pullover sweater that he was in the process of taking off.

The explosive sound had been generated when a huge slab of the mountainside suddenly broke away and opened a crack. The air rushing into the vacuum in the crack created the explosion-like sound. The wind that hit and picked up the running driver was caused by the mass of falling rock displacing air between it and the highway surface; the air rushed out with an amazing force.

About the same time that the loader operator had regained control of his machine, he realized that he had escaped the rockfall and that he was still alive. He turned his machine to move it farther up the highway. In the lights of the machine, he saw the truck driver sitting on the road. The driver was struggling with his leather coat, which was turned inside out over his head and arms. The loader operator had to help him remove the garment.

The small dump truck had been twisted and flattened by the falling rock. It was lying on the highway surface at the edge of the rockfall as though it had been crushed and then tossed aside.

The scene was amazing in the light of the following morning. The place where we had stood around the pickup truck on the rock was now seventy to eighty feet below the top of the rockfall. All three lanes of the highway and a wide shoulder on the outside were under the rock pile. About half of the total rockfall had gone over the highway and down the mountainside toward the Fraser River and the Canadian Pacific Railway. Fortunately there was a bench of land a few hundred feet below the highway where the rock had come to rest without involving the rail line.

Had the two men and their machines been working at the preliminary rockfall from the downhill side, they would have had no chance of escape and no chance of survival. The largest part of the main rockfall landed on the highway just below where the first small one had hit. From the uphill side they escaped by moving fifty to one hundred feet. On the lower side, they would have had to move at least four hundred feet.

The bench land below the highway was privately owned. The Provincial Government negotiated with the owner and bought a ten-acre piece of the land. The newly acquired land was used as a disposal site for the rock. Three large bulldozers were then brought in to push the slide material over the edge of the highway. Much of the rock on the road surface was in such large pieces that it had to be drilled and broken with explosives before even the largest bulldozers could move it. Crews worked around the clock for the next seven days before traffic resumed on that section of the Trans-Canada Highway.

The next time you pass through the Fraser Canyon and are about midway between Boston Bar and Lytton, watch for the scar above the highway on the side of Jackass Mountain, and the pile of broken rock below. You will be amazed that people who were there at the time of the rockfall survived it.