The 26th annual Awards for Engineering Excellence Gala, held Friday night at the Vancouver Convention Centre West, honoured the innovation and technical excellence of Association of Consulting Engineering Companies British Columbia (ACEC-BC) member firms. Klohn Crippen Berger (KCB) was presented with an Award of Merit for our work on a composite barrier wall/rock shed structure for CN.
On November 25th, 2012 a 53,000 m3 rock landslide occurred along the Canadian National Railway (CN) track at Mile 109.43, between Lytton and Boston Bar, British Columbia. The debris from the rockslide covered 70 m of track with debris up to 10 m deep, destroying a 21 m long concrete rock shed. This section of CN’s single-track mainline is part of the CN/CP Rail joint running initiative which sees all CN and CP Rail westbound traffic (Kamloops to Vancouver) running on CN tracks. Any service disruption on this line causes significant business losses to both railways and impacts the communities that rely on rail for the movement of goods.
KCB was contracted by CN to characterize and assess rock landslide hazard at the site; and recommend, design and implement measures to improve safety and protect train service at track level. Two protection structures were designed and constructed: a mesh attenuation curtain to act as a short-term rock fall barrier providing safe working conditions to the onsite construction personnel, and a composite barrier wall/rock shed as the long-term structure to protect the track from all identified potential rock landslides.
It was critical to minimize service disruption during construction of the composite structure along the operating railway. KCB’s innovative design solution was to use modular components, including the retaining wall, rock shed concrete roof panels and rock shed footings, which could be pre-cast and transported to the site.