Susanna McLeod
Special to Ontario Construction News
“You can’t get there from here,” says the cheerful idiom, portraying the difficulty of getting from one place to another. In the earliest 1900s, Toronto residents faced obstacles crossing the Don River and Rosedale Ravine to reach expanding city neighbourhoods. Council officials proposed bridges or a subway line. In 1910, bridges were out, but by January 1913, voters approved viaducts. Two years later, construction launched on the Bloor Street Viaduct over Don River (officially called Prince Edward Viaduct), and the Rosedale Valley Bridge.
Concerned residents insisted that engineers consider the natural beauty of the Rosedale Ravine, voting down several possibilities. Architect and urban planner John Lyle understood the complex construction brief. He recommended “a landfill terrace to continue Bloor Street south-eastward, and “figured that most of the earth for the landfill could come from the excavation for the viaduct in the Don and Rosedale sections,” stated City of Toronto in “Bridging the Don: The Prince Edward Viaduct.”
Engineers presented several design options. One proposal used all steel-construction, the second design was an all-concrete structure, and the third described a hybrid of steel and concrete. All three had benefits, and concrete came in at the lowest contractor bid. However, engineers thought that the Don Valley’s soft shale land base would not support the weight of the all-concrete design.
The City Engineering Department was tasked with producing reports, and after much Council debate, the hybrid steel-concrete design was selected. General Contractor Quinlan and Robertson was awarded the project contract in early 1915, “with the steel work sub-contracted out to the Hamilton Bridge Steel Works,” said City of Toronto. The project had three sections: the Don Valley, the Rosedale Ravine, and Bloor Street East on an embankment of the Ravine.
The viaducts—long, elevated bridges over low terrain—were planned as double-duty, with a roadway on top and a railway section beneath for future train traffic. Although Toronto’s viaduct project was an enormous undertaking, only between 200 and 250 workers were onsite.
Site preparations for the massive contract began with building boarding rooms for labourers and storehouses for supplies. “A carpenter’s shop, with an up-to-date set of tools, a blacksmith’s shop, and a machine shop” were set up, explained “Progress of Bloor St. Viaduct, Toronto” in The Contract Record (TCR), December 15, 1915. City water mains on Danforth Avenue supplied water needs, including drinking water and filling boilers. “Steam boilers placed at different points along the line of the viaduct serve the different hoisting engines and cement mixers.” Electrical engines powered smaller tools and woodworking equipment.
Cutting costs, earth for the project was accessed onsite. Excavating with a Marion steam shovel, the operator scooped bucketloads of earth into train dump cars. The material “was hauled up an incline over the C.P.R. tracks and distributed from there wherever needed over the Don Valley for grading about the piers and building up low leads,” TCR said. In total, 25,000 cubic yards of earth were moved.
Piers were excavated down to bedrock, and sheets of wood were installed to keep back soil and water. The wood “was left in place when the concrete foundations were poured,” noted City of Toronto. “The contractors erected elevator towers with concrete mixers nearby,” and prepared concrete “was fed into the tower hoppers, and then lines of steel chutes delivered the concrete to the piers.”
Skilled workers created a complicated framework of timbers as temporary “falsework” supporting steel arches until the metal was securely fastened with steel rivets. Upon completion of structural work, the bridges were surfaced with wood blocks soaked in creosote, a standard method in that era.
Opened to traffic on October 29, 1917, the Rosedale Valley Viaduct with one central arch measured about 183 metres long, rising 29 metres above the Ravine. The Bloor Street Viaduct was scheduled to officially open on October 18, 1918, but the Bloor section was delayed until August 29, 1919 due to settling. Towering thirty-eight metres above the Don River, the five-arch Don Valley bridge was over 510 metres in length.
The planned rail line at Bloor Street Viaduct sat unused for decades. Repurposed, the Bloor-Danforth subway line opened on February 26, 1966, today carrying TTC Line 2 passengers. The lower span of the Rosedale Valley Viaduct did not open; the approach curves deemed too sharp for rail use. The original cost estimate in 1910 was under $800,000; the final price was a mind-boggling $2,480,349.05.
In 1986, the impressive Prince Edward Viaduct, plus Commissioner R.C. Harris and engineer Thomas Taylor, received well-deserved recognition as a National Historic Civil Engineering Site by the Canadian Society of Civil Engineering, with plaques at the bridge ends. In 2018, City of Toronto installed a Commemorative Heritage Plaque, celebrating the Viaduct’s centennial.
Torontonians can now “get there from here,” thanks to precise engineering of Prince Edward Viaduct project. END 800 words
Susanna McLeod is a Kingston-based writer specializing in Canadian history.
