Plaque(s)

Description of Historic Place

The Québec Bridge National Historic Site of Canada is a steel cantilever bridge which links the shores of Québec City and Lévis over the St. Lawrence River, located a few kilometres upstream from Québec City. Built in 1917 with a total length of 987 metres and a height of 95 metres, the bridge is comprised of north and south approach bays, anchor piles and arms, two main pillars resting on the river bed, cantilever arms, and a 500-metre suspended section between them. Official recognition refers to the bridge itself, its anchor pillars and the two main pillars on the river bed.

Heritage Value

The Québec Bridge was designated a national historic site of Canada in 1995 because: it is the longest clear-span cantilever bridge in the world, the first major bridge to use the K truss which greatly facilitated its erection, and the first bridge in North America to use nickel steel in its construction; a remarkable engineering feat, the Québec Bridge was largely conceived and built by Canadians.

The Québec Bridge, with its 500-metre free span between the two central pillars, is the longest cantilever bridge of its kind in the world. Built using the K truss system, in which two diagonal beams support one vertical beam (forming a ‘K’ shape), the bridge is also remarkable for the use of nickel steel in its construction. Although this stronger alloy was more expensive than the more popular carbon steel, it allowed engineers to attain the record-breaking length of the bridge’s suspended section.

The bridge was designed and constructed principally by Canadian companies under head engineer H.E. Vautelet. Its construction was facilitated by the K truss system, but also by the manner in which the suspended section was installed. Constructed separately, this section was floated on the river to the cantilever arms and raised, where it was riveted in place. Because of its size and innovative design, the Québec Bridge remains one of the most important bridges in the history of civil engineering in Canada, as well as an important symbol of Québec City.

Source: Historic Sites and Monuments Board of Canada, Minutes, November, 1995.

Character-Defining Elements

Key elements contributing to the heritage value of this site include: its location and setting over the St. Lawrence River, spanning the shores of Québec City and Lévis; its 500-metre span between abutments, the longest of its kind; its distinctive form, scale and massing, as expressed in its vertical and diagonal steel beams and masonry pillars; its linear footprint and geometric profile; its structure composed of approach bays, anchor piles, anchor arms, cantilever arms resting on masonry pillars and joined by a suspended section; the cantilever design of the bridge, including the K truss system with two diagonal beams supporting one vertical beam, all connected with rivets; the integrity of the materials used, including the carbon steel used for the bridge structure, anchor arms, cantilever trusses, and vertical compression pieces, the use of nickel steel on most of the tension pieces, as well as the masonry pillars; the integrity of its construction technology; its commemorative plaque near the north entry from Canadian and American Engineering Societies, designating the Québec Bridge as an international monument to civil engineering; viewscapes from both shores and from the bridge toward Québec City and Lévis.