Innovative Rockfall Netting System Aims to Improve Safety at Three Valley Gap

Work crews install fencing as part of our pilot rock fall fencing system at Three Valley Gap on BC Highway 1.

About 20 kilometres west of Revelstoke lies a short stretch of BC Highway 1 with a unique geography.
Running in-between Three Valley Lake and the Monashee Mountains, Three Valley Gap is, quite literally, located between a rock and hard place. In fact, next to the Kicking Horse Canyon, this may be the most technically challenging section of the Trans-Canada Highway, in the entire province. We love technical challenges, but not nearly as much as we love keeping the travelling public safe, which is why we are excited to announce the installation of an innovative pilot rock fall fencing system that will help keep people travelling safely in the Three Valley Gap area.

Geography, intense weather and snow avalanches in the area mean standard rock fall fencing would not survive the avalanche activity that takes place along the corridor. So, the new fencing system will reduce the chance of rocks landing on the highway and withstand potential damage caused by snow loading and avalanche activity, without compromising the effectiveness of the remote avalanche control systems that were installed in the area in 2017. The remote avalanche control system also helps the fencing system by keeping the snow avalanches smaller in size – reducing the snow impact on the fencing.  We think it’s a pretty great thing.

Work crews install fencing as part of our pilot rock fall fencing system at Three Valley Gap on BC Highway 1.

The fence is approximately 122 metres long and consists of 5-metre high steel posts spaced about 10 metres apart.  These posts are supported by a network of steel cables that are anchored 6 metres into bedrock.  The slope mesh material consists of two layers of high strength steel rockfall control netting which are hung from the cable supports. This innovative fencing was designed by ministry engineers using materials developed and tested in Europe. If the pilot is successful, this type of system will be considered for other rock fall areas at Three Valley Gap.

British Columbia’s mountainous landscape means our highways pass through some challenging terrain, but our Rockfall Program is dedicated to reducing the rockfall hazard for highway travellers. Do you have a question about this, or anything else the ministry does? Let us know in the comments below.

An avalanche of snow passes freely through the rock fall fencing at Three Valley Gap. Creating a fencing system that was strong enough to stop rockfall and yet nimble enough to allow through is part of what makes this fencing system so innovative.

Did you Know?
In the fall of 2018, a 33-metre long retention wall was also installed in the area to address potential large boulder events.

An aerial shot of the retention wall after installation.
A close-up of the retention wall being installed along the Three Valley Gap stretch of BC highway 1.


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Page 1 of 12 comments on “Innovative Rockfall Netting System Aims to Improve Safety at Three Valley Gap”

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    • Hello Inga – thanks for your comment. By up and over, do you mean up over the mountain at Three Valley Gap?
      Unfortunately, the rock in this area is not right for tunnelling and the grade would be too steep, especially in winter to safely drive. Hope this information is helpful.

  1. While the word’s advanced nations build super highways through mountains, Canadians get nets to stop rocks falling on their decrepit goat trails.

    Google “China Mountain Highways” and be amazed.

    The technology is here, we’re one of the wealthiest countries, yet, somehow, we’re paying hundred of millions of dollars from collective budgets to private shareholders to keep business open instead of just building our own. That sounds more like a hostage situation rather than “economic stimulus”.

    • Thanks for your comment, Pim. Unfortunately, neither tunnels nor sheds are viable due to the unsuitable rock that makes up the Three Valley bluffs. We continue to work on other ways to improve safety at this location.

    • Thanks for your feedback! Yes – tunnels and bridges are very costly items. This fencing is a trial system which we hope will work well in this tricky spot.

  2. Hope that netting is designed to withstand 30 or 40 years of rockfall and avalanche debris (which often includes rocks and timber). Because it looks like there is no hope of that section of highway EVER being upgraded.