An engineering company has been selected to design the rehabilitation of the Cambie Street Bridge.
The City of Vancouver initiated the procurement in light of findings that the bridge is not up to modern earthquake standards.
“After a moderate level earthquake, the Bridge would likely need to be closed and require replacement,” according to a staff report in the Wednesday (April 3) agenda of council.
The report was prepared by Alexander Ralph, senior manager with the city’s supply chain management operations.
Ralph recommended that council approves a $5.5 million consulting contract with Associated Engineering (B.C.) Ltd.
“Although the Bridge has been constructed fairly recently, our understanding of seismic performance of structures has changed since the 1980’s,” Ralph wrote. “Lessons learned from recent earthquakes (Northridge, Kobe, and Christchurch) have led to advances in our understanding of structural response and, subsequently, revisions to applicable design codes.”
The manager recalled that the city had been commissioning studies regarding the bridge’s “risk profile” since 2008.
“In 2013, a preliminary seismic assessment was completed to develop a better understanding of the bridge’s expected seismic performance, as well as some of its apparent and/or potential deficiencies,” Ralph noted. “The foundations, columns and other structural components were identified as being deficient, along with concerns for potentially liquefiable soils.”
Ralph went on to recount that geotechnical data was collected in 2014.
“A geotechnical seismic assessment followed, where it was concluded that liquefaction was a concern along the bridge’s alignment and ground improvement options were developed, for consideration,” according to the manager.
According to Ralph, the bridge will be rendered inoperable after a moderate level earthquake.
“From the various studies it has become clear that the Bridge does not meet the current seismic code (Canadian Highway Bridge Design Code S6-14) requirements and, given the increased seismic hazard and potential for soil liquefaction, the Bridge is not expected to perform well,” Ralph stated.
Ralph also wrote in his report that around 55,000 vehicles use the Cambie Bridge every day.
The crossing over False Creek was constructed in 1985.