In 2007, the gross stock of bridges and overpasses amounted to $23.9 billion, or 8% of the five assets combined. Unlike roads however, investments on bridges have been under the level required to hold their age constant. Hence, ageing has been the rule since the mid-1980s. The average age of bridges went from 21.3 years in 1985 to 24.5 years in 2007, an increase of 3.2 years.
Between 2001 and 2007, the gross stock in these assets grew only 0.4% a year on average, causing the average age of bridges to increase by 0.8 years during this period. The ageing process has been fastest in Prince Edward Island (+5.1 years) and Nova Scotia (+4.4 years).
While bridges last longer than roads, they remain an important piece of the road network. They require regular inspection and investments to ensure that they are safe to use and in good condition.12 Bridges have a mean service life estimated at 43.3 years. In 2007, bridges passed 57% of their useful life, compared with 53% for roads. In this same year, the ratio for bridges was the second highest of the five assets covered in this study, after wastewater treatment infrastructures.
Provincially, the ratio for bridges ranged from an exceptional low of 36% in Prince Edward Island (thanks to the Confederation Bridge) to peaks of 66% in Nova Scotia and 72% in Quebec.
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12. See "Commission of Inquiry into the Collapse of a Portion of the De la Concorde Overpass", Gouvernement du Québec, 2007, http://www.cevc.gouv.qc.ca/Rapport/index.html (accessed December 20, 2007).