The Importance of Bridge Rehabilitations
Construction Business | Spring 2025
Mark Bowen, MEng, P.Eng., CEng, MIStructE | Principal
That bridge you crossed on your morning commute was designed to last up to a century. But for Canada’s bridges to achieve their 75- to 100-year lifespans, rehabilitation is an essential investment. Bridge rehabilitation, by definition, is the partial replacement of a bridge to maximize its lifecycle and maintain safety. With everyday foot and vehicle traffic well in the thousands on many aging bridges, ensuring that infrastructure is maintained to support expected loads is essential for public confidence and more importantly, community safety.
When it comes to local bridge infrastructure, municipalities bear responsibility for the inspection and maintenance of their structures. As soon as a new bridge is built, it’s added to the municipality’s inventory. From there, inspections are programmed every two to three years. This involves on-site visits to review the bridge structure’s condition, identify elements that are deteriorating or simply not performing well, and reflect updates in an asset management database.
By the time a bridge turns 25- to 40-yearsold, municipalities identify elements that have deteriorated sufficiently to need repair. Water and de-icing salts that seep through joints at either end of a bridge are common culprits that start to degrade the critical steel and concrete structure below. Not surprisingly, early maintenance and rehabilitation of expansion joints can protect the underlying structure and defer more substantial repairs to later in the bridge’s lifecycle.
Adding to pressures from water and salts are thermal changes. With temperature swings from -40°C winters to +30°C summers, Canada’s harsh climate adds stress to bridge components.Large thermal movements are typically accommodated in the expansion joints and bridge bearings. However, uneven geometry or loading can cause degradation of these elements. One rehabilitation strategy gaining favour is to consider removing joints altogether by revising bridge articulation to a semi-integral configuration which can eliminate one of the primary sources of structural deterioration.