Brief
Engineers and contractors tasked with replacing the flood-prone Windsor Bridge in Sydney, Australia, leaned heavily on concrete to create a highly resilient structure, as raising the bridge to avoid flood waters altogether was not feasible. Built using incrementally launched precast bridge sections and concrete piers and abutments, the bridge was designed to better handle and rebound from severe flood events and the structure was largely unscathed and reopened after being submerged in each of its first two years.
Insight
At A Glance
Project: Windsor Bridge
Builder: Georgiou
Main Concrete Elements:
- Incrementally launched precast bridge sections
- Concrete piles/piers, abutments
Originally built for horse-drawn vehicles and foot traffic in 1874, the Windsor Bridge had reached the end of its life by the early 2000s.
Constructing something high enough to completely escape floodwaters wasn’t feasible, so the challenge was to construct a replacement bridge that could better cope and rebound from severe flood events.
Solution and outcome
At 156m long, the new bridge comprises three lanes—two southbound and one northbound.It is located 35m downstream of its predecessor and is 3m higher at the northern bank and 6m at the southern bank.Delivered by contractor Georgiou, the new bridge was constructed as an incrementally launched bridge, with 10 concrete segments cast in a bed on the northern bank before being launched across the river.
The bridge superstructure is supported by four piers in the river. The piles for these piers were constructed from steel tubes filled with reinforced concrete, then topped with precast concrete pile cap ‘shells’ filled with concrete to support the bridge columns.
Although the flood immunity of the new bridge is around the one-in-three-year flood level (compared to one-in-two for the old bridge), its real benefit stems from its strength and ability to resist damage that would otherwise result in lengthy and costly repairs.
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