New rail bridge will reduce flood risk

A replacement railway bridge in central Whangarei is expected to reduce flood levels in the Morningside area.
As part of an ongoing replacement strategy, KiwiRail has announced it will demolish the current timber bridge across the Waiarohia Stream on Railway Road, and build a new one with fewer piles, increasing the channel capacity.

The large number and placement of piles on the two existing railway bridges significantly obstruct the channel when the stream is in flood, backing up the stream and causing it to overflow.

Stream levels have been estimated as almost a metre higher upstream of the bridge than downstream of it during storm flows.

Whangarei District Council stormwater asset engineer Conal Summers says removing the current bridge should make a significant difference in clearing storm flows from the city area.

“The bridge was identified during earlier work on the Whangarei CBD Flood Management Study as a major restriction in the network, so it is very positive KiwiRail recognised the problems being caused by the bridge, and has incorporated this into its design,” Mr Summers said.

The bridge replacement is part of KiwiRail’s long-term programme to remove timber from the rail network, which is designed to improve reliability and efficiency and reduce ongoing maintenance costs.

Tenders for the work closed today (November 16), and work is expected to be completed next winter.