After over six months of installation and testing, the Pattullo Bridge now has an advance seismic and high wind warning and bridge closure system.
TransLink’s interim safety systems for the remaining lifespan of the rapidly deteriorating bridge is designed to detect early warning signs of significant seismic ground waves or a high wind event. For earthquakes specifically, the advance seismic warning system will provide alerts of up to one minute prior to damaging ground waves reaching the bridge.
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When the system detects early warning signs of an earthquake or significant high wind event, traffic control gates at the entrances onto the bridge deck will descend and block vehicles from entering the roadway.
Advance warning lights and digital bridge closure signs have also been installed to alert drivers of an immediate emergency closure.
#TransLink‘s new advance seismic & wind warning detection system for the Pattullo Bridge is now online. It can detect earthquakes up to 1 min before the shaking.
— Ken Chan (@iamkennethchan) February 7, 2020
According to a previous TransLink report, the 1937-built bridge’s poor condition makes it highly vulnerable to collapse during a moderately powerful earthquake or even hurricane force winds.
The bridge’s piers in the Fraser River are also designed in a way that a ship strike could lead to structural failure.
Furthermore, the existing crossing has been a hotspot for fatal collisions due to the narrow width of the lanes and the lack of a concrete divider between directions.
Over the past decade, TransLink considered a number of schemes to provide the bridge with emergency temporary upgrades, with rehabilitation project scopes ranging between $100 million and $299 million. But these plans were ultimately cancelled — deemed exorbitant given the plan to replace and demolish the bridge.
Instead, the public transit authority proceeded with a strategy of more economical measures such as the advance warning system, and periodical inspections and maintenance work.
In 2018, the provincial government took over TransLink’s responsibility of funding and delivering the bridge replacement project to allow the public transit authority to better focus on its transit expansion program.
Last month, BC Ministry of Transportation announced the joint partnership between Acciona Infrastructure Canada and Aecon Group Inc. had been selected as the main contractor for the $1.4-billion replacement project. Construction is expected to begin sometime later this year.
Upon the completion of the new four-lane bridge in 2023, the existing structure will be decommissioned and demolished. TransLink’s previous studies indicate the existing bridge would need to close by 2024 at the very latest given its rate of deterioration.