Canal Lake Arch Bridge. Photo: Bruce Forsyth. 
Canal Lake Arch Bridge. Photo: Bruce Forsyth.
September 2021
In the mostly rural municipality of Kawartha Lakes, Ontario, a historic arch bridge can be found. Stretching over the Trent-Severn Waterway near the settlement of Bolsover, the Canal Lake Concrete Arch Bridge, a single arch bridge, braced by abutments on either shore, is the earliest known reinforced concrete bridge in Canada, having been erected in 1905.
Located on the south side of Canal Lake, the deck of the bridge is 16 feet wide, and spans 202 feet over boating canal. The arch, which has a radius of 30 feet and a vertical clearance of 29 feet, is a closed spandrel arch; an arch supported by vertical sidewalls, or spandrels, with the roadway on a deck atop the arch.
The concrete structure is reinforced with curved, solid steel girders inside the concrete, known as the Melan reinforcing system, developed by Joseph Melan in 1893. This method allows for less concrete to be used, than an unreinforced structure. The exterior of the concrete is enhanced by markings on the surface, which simulate the voussoir stones of masonry arches and the coursed stonework of stone masonry bridge abutments.
The Canal Lake Arch Bridge was part of a transition from stone arch bridge construction to reinforced concrete construction. This new method proved so successful as a bridge building material, that it was used in other canal structures along the Trent-Severn Waterway and elsewhere. It was the forerunner of large-span, reinforced concrete bridges, with arch bridges representing an important advancement in the history of civil engineering in Canada.
The Canal Lake Arch Bridge was designated a national historic site of Canada in 1988.
The bridge underwent a complete refurbishment in 2018, allowing it to carry on through its second century of providing passage for travelers in Kawartha Lakes.
Top side of the Canal Lake Arch Bridge. Photo: Bruce Forsyth.
Sources: https://cottagelife.com/general/gravenhurst-seeks-public-input-on-future-of-historic-train-station, https://en.wikipedia.org/wiki/Gravenhurst_station, http://www.muskokarailsmuseum.com, Canal Lake Concrete Arch Bridge – Wikipedia, NCDOT: Reinforced Concrete Closed Spandrel Deck Arch Bridges, Canal Lake Bridge (Hole in the Wall Bridge) – HistoricBridges.org.
