Upper Hunter MP Michael Johnsen said the NSW Government and Australian Rail Track Corporation (ARTC) jointly funded the project to enhance the rail bridge, widen the New England Highway and provide a new shared path and facilities for cyclists and pedestrians.

"About 22,000 vehicles travel through the Gowrie Gates every day, including more than 400 heavy vehicles," he explained.

"Widening this section of the New England Highway and replacing the rail bridge has improved access for oversized heavy vehicles as well as increased safety for all road users and is part of a broader strategy to provide rail network reliability."

Minister for Regional Transport and Roads Paul Toole said the upgrade reflected the government's commitment to improving traffic flow and freight productivity, as well as reducing travel times through the Hunter.

"We are delivering important infrastructure for regional communities that makes it easier and more efficient to get around," he added.

Mr Toole said the project had been completed several months early - the third to be finished ahead of schedule in the Hunter in the past 12 months.

"The duplication of Tourle Street and Cormorant Road in June 2018 and the M1 Upgrade at the Weakleys Drive intersection in March 2019 were both delivered ahead of schedule," he told ACM.

ARTC group executive Jonathan Vandervoort said the Gowrie Gates project would improve access and travel times for over-dimension freight movements on the New England Highway.

"The project has a new minimum 5.4 metre vertical clearance at the rail bridge and will help minimise freight disruptions along the highway," he explained.

"It will also improve the movement of bulk coal on the Main North railway line, a vital transport link which carries one of NSW's most valuable export commodities.

"Upgrade work on a 260m section of the highway has provided two 3.5m lanes and wide shoulders at the underpass, to meet current road safety standards.

"We would like to thank the community for its patience and support during the delivery of this project."

Further information and time-lapse footage is available at rms.work/GowrieGates