The Knight Street Bridge, opened to traffic in 1974, is one of the most important crossings of the Fraser River between Vancouver and Richmond. The four-lane bridge includes two separate river crossings comprising elegant concrete spans of up to 110 m and a large number of concrete approach viaduct spans.
TransLink retained Associated Engineering as prime consultant to perform an independent seismic assessment of the bridge. A key objective of our study was to investigate higher levels of seismic demands and performance requirements than studied previously by the Ministry.
Other key tasks included development of detailed, specific seismic performance and assessment criteria; development of site-specific seismic loading for seismic events having 500-year and 1000-year return periods; a detailed close-proximity condition survey of the entire bridge; non-destructive testing of the deck and post-tensioning tendons; development of preliminary and detailed designs for an overall seismic and condition upgrade of the bridge, bridge deck, foundations and liquefiable soils; and coordination of the proposed upgrades with safety upgrades being investigated for the crossing by others.
Two essential aspects of our retrofit and rehabilitation strategies were the integration of the seismic and rehabilitation works into a holistic, high value scheme, and the selection and design of the works to allow a safe, staged construction program with work to be completed without unacceptable impacts on the high traffic volumes that use this major transportation link.