A Brief History of the Kinsol Trestle

The Canadian Society for Civil Engineering will designate the Kinsol Trestle near Shawnigan Lake, BC, as a National Historic Civil Engineering Site in 2022. Canadian National Railways completed this massive structure, also known as the Koksilah River Trestle, in 1920. It is noteworthy for: (1) the scale and complexity of its original design and construction; (2) the operational and engineering challenges during its long railway service life; and, (3) the innovative rehabilitation design and construction to repurpose the trestle and extend its service and heritage value on the Cowichan Valley Trail which is part of the Trans Canada Trail. Built with a seven-degree curve, it is 44 m high, 187 m long and so remains today as one of the largest and highest wooden trestle bridges in Canada, representing an enormous feat of engineering and construction. It provided rail service and contributed to development of Vancouver Island for close to 60 years—the last train crossing was in June 1979. Rehabilitation of the trestle, completed in 2011, involved the replacement of 17 of the 46 bents using all-new wood and erecting under-slung custom-built steel trusses to “bridge” between the active bents. The remaining 29 original bents are simply left in place as inactive, non-load-bearing elements. This paper briefly describes the history of this remarkable structure.