A new warning system for the Pattullo Bridge to alert drivers ahead of an earthquake is expected to go live later this year.
The “advanced warning system” will monitor wind speeds and also detect earthquakes to “provide alerts up to one minute prior to damaging ground waves reaching the bridge,” according to a report considered at a Sept. 25 meeting of the Mayor’s Council on Regional Transportation.
In an emailed statement, TransLink told the Now-Leader that the system will involve the installation of ground sensors that detect seismic activity.
“Once the system is activated, gates, similar to railway gates, come down to prevent traffic from crossing the bridge. In addition to the gates, the system also consists of advance warning flashers and signage for vehicles, cyclists, and pedestrians,” the statement explained.
The current crossing is more than 80 years old and was not designed to meet current wind and seismic loading standards that would apply to a new bridge constructed today, the report notes.
“As result, may be vulnerable in a seismic or hurricane-level wind event,” the Mayors Council report states. “To improve safety for Bridge users, an advance warning and monitoring system is being designed and implemented.”
PBX Engineering has completed the design work, and the contractor Mainroad has started construction.
TransLink expects the system to go live in December.
The system is not installed on any other bridges owned and maintained by TransLink, which are the Knight Street, Golden Ears, and Westham Island bridges.
With plans for a Pattullo Bridge replacement underway, TransLink is continuing to monitor the condition of the current crossing.
This year, TransLink also plans to do more repairs to some of the bridge’s railings, with some of that work already completed earlier in 2019.
“A total of 606 railing posts were inspected and assigned deficiency ratings based on their observed conditions. Of the 606 posts inspected, 128 posts were classified as needing immediate repair or replacement,” according to the TransLink report.
A condition inspection was also completed in late July.
“No new areas of concern have been reported so far as a result of the July 2019 inspections,” the report notes. “TransLink will continue to perform annual monitoring as well as any additional investigations and repairs as required if any areas of concern or accelerated deteriorations are detected.”
The condition of the bridge’s concrete deck is also being monitored, as it is in an “active and advanced state of deterioration, primarily due to corrosion of the reinforcing steel.”
TransLink says to ensure the deck remains “functional and safe,” deck experts are conducting bi-weekly walk-through inspections from the deck, ground and catwalk levels.
In addition to the top surface of the deck, TransLink reports that “extensive corrosion-related damage is also occurring to the bottom surface (soffit).”
Debris netting is currently in place to protect the public and other infrastructure, including the railway tracks, from concrete falling from the deck soffit.
Northwest Hydraulic Consultants also conducts bi-annual surveys assessing risks from the changing of river hydraulics.
In its most recent survey, NHC recommended more frequent protection surveys, due to upcoming in-river works required in building the replacement crossing.
Meantime, the $1.3 billion replacement of the bridge linking Surrey and New Westminster is scheduled to start by the end of 2019 and be completed in 2023. Built north of the existing 80-year-old structure, the new bridge will still have four vehicle lanes, plus pedestrian and bike lanes and a new off-ramp to Highway 17, the South Fraser Perimeter Road.
-With files from Tom Fletcher