The new $16.5 million Lily Street bridge over the railway line at Allawah has opened to traffic.
Work was completed on schedule after a year of construction and the crossing being closed for seven months.
The bridge has four lanes compared with two on the previous structure.
But the configuration is unusual, with only one northbound lane and three southbound lanes, including a left-turn lane, right-turn lane and another for through traffic.
The design was based on traffic studies by the former Hurstville Council and had the support of the former Kogarah Council.
The studies found the majority of congestion was created by south-bound traffic.
The project stems from a bidding war at the 2011 state election, with both major parties promising funding.
Nearly six years later, it has become a reality.