Railway Protection Structures
Ashcroft, British Columbia, Canada
Design and construction
ACEC-BC AWARD OF MERIT
Composite barrier wall and rock shed structure
Tim Keegan Ph.D., P.Eng.
Risk assessment and design of railway protection structures in the Fraser Canyon, British ColumbiaIn 2012, a significant rockslide occurred in the Fraser River canyon across a section of Canadian National Railway’s single-track mainline between Kamloops and Vancouver. KCB was retained to assess the residual risk and to design structures to protect the railway from future rock falls. KCB’s modular rock shed design allowed for construction under railway traffic.
The design and construction of the composite barrier wall and rock shed structure was tested by a second significant landslide on December 11, 2014. The railway was protected from the landslide with no harm to people or property, and no rail service disruption.
- Inaccessible, steep landslide area for investigating the site
- Understand why and how rock slope failed
- Design protective structures for unstable steep slope
- Develop construction sequence with minimal rail service disruption
- Difficult working conditions from continued rock and debris falls
- Adopted LiDAR remote sensing techniques for mapping rockslide and adjacent rock slopes
- Used finite element analysis with discrete fracture network models to reproduce slope failure mechanism
- Applied dynamic run-out analyses to determine potential impact loads (through normal and shear stresses) on proposed protective structures
- Designed barrier wall and rock shed using pre-cast, modular concrete panels and footings
- Installed temporary mesh attenuation curtain to guide fallen debris safely under a tail drape
- Mapped slope geology and geomorphology
- Developed landslide triggering factors and potential failure mechanisms
- Determined failure mechanism where rock surface slid along stepped surface
- Calculated volume (magnitude) of landslide materials
- Developed appropriate design parameters for protective structures, consisting of mesh curtain, composite barrier wall and rock shed
- Minimal disruption to rail service during construction of protective structures
- No injuries to workers or new disruption to rail service due to occasional rock and debris falls
Busslinger, M., O. Hungr, T. Keegan, W. Wu and T. Edwards. 2014. “Rock Mass Fall: Rock Avalanche Design Loads for Railway Track Protection“.
Keegan, T., B. Willoughby, T. Edwards, M. Busslinger, M. Sturzenegger and A. Wen. 2014. “Construction of a Composite Barrier Wall/Rock Shed Structure at Mile 109.43 of CNR’s Ashcroft Subdivision“.