How We Keep Rock and Debris off BC Highways

workers clearing debris from rockface

British Columbia is home to some of the most picturesque landscapes in Canada. But with large amounts of precipitation, lush vegetation and mountainous terrain, it’s also prone to rock and debris falls.

Our team of engineering geologists and geotechnical engineers have enhanced measures for reducing the impact of rock and debris fall.

Spraying Shotcrete along Trans-Canada Highway in the Southern Interior

Active Measures

Steps we take to reduce the impact of a landslide when it happens include:

  • Trench: a hole dug at the slope’s bottom, which prevents falling rock and debris from landing on the road.
  • Retaining wall: a solid structure designed to keep falling rocks and debris from reaching the highway.
  • Catch fence: designed to be flexible and absorb energy, fences are constructed using steel posts and steel net panels. The net panels can expand several metres to absorb the impact of falling or rolling rocks.
  • Slope mesh: draped steel wire mesh directs rockfall into highway trenches. The slope mesh is suspended at the top of the slope from a system of steel bars, or anchors, drilled into the rock with support cables. Rolls of mesh are then lifted into place by helicopter or crane, then unrolled and stitched together to form one continuous protective blanket.
Catch fence along Trans-Canada Highway near Cache Creek

Preventative Measures

We take steps to reduce the risk of a landslide happening. This work includes:

  • Drain holes: horizontal holes are drilled into the slope and lined with drain pipe to help relieve built-up water pressure from underneath the surface.
  • Trim blasting: removal of rock using closely spaced drill holes loaded with explosives. Usually, holes are drilled by workers suspended from ropes using handheld drills called “pluggers,” but drilling may also be performed out of cranes or man-lifts with bigger drills.
  • Shotcrete: Ever wonder what that clay-like coating is over rock walls? It’s special fluid-like concrete, sprayed on to support loose and fractured rock.
  • Rock bolting: stabilization of rock using tensioned steel bars. Holes are drilled into the rock at locations where there is potential for blocks of rock to fall off the slope. Bars are then cemented into the rock to hold the large blocks into place. The drilling is usually performed from a suspended staging called a “spider,” but may also be conducted from cranes or man-lifts. Each rock bolt can support several tons of rock.
  • Berms: masses of blasted rock or heavy boulders are placed at the base of a slope to help support and prevent sliding.
  • Rock scaling: removal of loose rock. Workers, nicknamed “Rock Scalers,” access the slope suspended from ropes. Scaling is usually the first activity conducted on a rock slope to remove any loose material that presents a hazard to traffic and workers.

Some of these measures can be seen from the highways, while others are hidden; all are working to keep travellers safe. Next time you’re driving through a mountainous section of highway, impress your friends by listing off some of the ways the looming rock and debris is kept in place. Then again, maybe just admire the picturesque landscape.

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Page 1 of 3 comments on “How We Keep Rock and Debris off BC Highways”

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    • Hi there JS,

      The province itself manages this work through groups of geotechnical engineers and technicians. If you have a question, we would be happy to share it with our team and hopefully get you the information you are looking for.