Floods will still affect the Pacific Highway between Grafton and Iluka, even once the upgrade is complete.
The road surface will only be above a one in 20 year flood peak, even though river levels have exceeded that height three times in the past five years – the latest just a few weeks ago.
The Department of Roads and Maritime Services acknowledges a section of new road will be built on a flood plain.
However, a spokesperson says bridges and drains will be designed to ensure minimal impact on properties.
