CN Thorton Rail Tunnel
CanMine executed an infrastructure upgrade of the 3.4 km long Thornton Railway tunnel’s ventilation and lighting systems. This tunnel is an extremely vital link to the North shore of the Port of Vancouver and was one project of many to increase throughput on the rail line. The improved ventilation system was needed to increase number of trains per day through the tunnel. The work was completed in a highly disruptive environment as the train traffic could not be stopped. All work was completed on time between trains on a 24/7 schedule.
The ventilation system was made up of sixteen axial fans that we installed on the tunnel crown. Each fan was mounted to a stainless steel fan frame. Each frame was held in place with six galvanized threadbar bolts that had to be cement grouted. Elevation control was important as there was minimal headroom available above the trains to the existing tunnel crown. The bolts had to be precisely drilled and installed to allow for rapid hanging of the fan frame between trains.
The 3.4 km tunnel has an access shaft near the centre of the tunnel which daylights in a residential part of Burnaby. Each fan required home run cabling for both power and control back to the shaft, then up the shaft to the power supply at the top of the shaft. Power supply required installation of new sub-station, fan starters, and PLC control system.
Cables were all routed through a concrete cable trough that CanMine installed in the ballast next to the rail line.
The shaft required a lot of rehabilitation in the lower section where there was large failure of the original shotcrete lining covering the glacial hard pan. CanMine had to complete this rehabilitation before installation of any new cables from the tunnel up to the control building at the top of the shaft.
The project has numerous challenges that CanMine had to navigate through with the worst being that we had to work through the worst period of the Covid pandemic.
Commissioning was done over Christmas and New Years when minimal train traffic allowed for full flow ventilation testing.
The design of the infrastructure was by engineering firm Mott MacDonald and CanMine’s sub-contractor for the electrical work was Mott Electric.
