Canal Lake’s Arch Bridge
In the mid nineteenth century, bridges in the Kawartha Lakes region were typically wooden, employing trestles as necessary depending on the span. These wooden bridges sometimes required painstaking filling to reduce their length—moving tons of stone by hand before the advent of earth moving machinery. In the final decades of the century, steel bridges became common and some examples of steel bridges from this era are still standing today.
At the turn of the century, concrete was a new building product and few local builders were familiar with its use. In nineteenth century Ontario, it was a challenging material to work with—to mix concrete successfully, clean water, pure aggregates and high quality cement (all ingredients that were hard to come by) needed to be mixed in precise proportions. Trent Waterway engineer R.B. Rogers was a pioneer in concrete construction, creating a laboratory in the basement of his Trent Canal office to experiment with different mixes, to maximize the strength, durability, and water resistance of concrete. Construction began on the Otonabee Lock, his first concrete lock, in 1896, followed by the Peterborough Lift Lock, which remains the highest lift lock in the world. To provide the materials for these projects, a local concrete industry was born.
When work began on connecting Balsam Lake with Lake Simcoe, Rogers commissioned another monumental lift lock at Kirkfield. His plans for this section included creating two artificial lakes—Canal Lake and Mitchell Lake, both of which involved digging a canal through a forest, before flooding it. On Canal Lake it was then necessary to bridge the newly created canal. Even though the reputable Dominion Bridge Company of Montreal helped build the Kirkfield Lift Lock, a concrete bridge was chosen, but designed to look like a traditional stone bridge, with abutments on both shores. It was even detailed to give the appearance of voussoir stones over the archway, with coursed stonework on either side—at first glance many observers might mistake it for traditional masonry. When it was completed in 1905, it became the first reinforced concrete bridge in Canada.
The Canal Lake Arch Bridge was designed based on Austrian Engineer Josef Melan’s System. Instead of using iron bars to reinforce concrete, he incorporated a rigid iron truss into the structure. In 1898, he had built the longest reinforced concrete bridge in the world at Steyr, Austria at 42.4 metres. The Canal Lake Bridge does not take advantage of this principle to create a shallow arch, rather its opening is almost a 30 foot semi-circle, hence its nickname “the Hole in the Wall Bridge.” It is 202 feet long and 16 feet wide.
When it was first completed, the bridge presented an unusual appearance. The drowned forests were not cleared until after the opening of the Kirkfield Lift Lock in 1907—so this marvel of engineering would have initially been surrounded by a large, dying, flooded forest. Once the trees were cleared and the lake naturalized, the bridge became a much appreciated architectural feature, one of the many interesting sights along the course of the Trent-Severn Waterway. In 1988, it was designated a National Historic Site.
In 2008 Bruce Stanton, Member of Parliament for Simcoe North unveiled a plaque on the site, but the bridge was beginning to show its age. The City of Kawartha Lakes closed it on April 16, 2018 so GMP Contracting could refurbish the bridge, replacing the concrete deck, curbs and walls. Completed in March 2019, the old concrete bridge, designed for horse traffic, is once again carrying horseless carriages. Born in the age of horses it is narrow for motor cars, but that it just one of its many charming features.
