More than $48 million has been allocated to fix Coulson's Creek Road, including $38.6 million in federal money and $9.66 million from the state.

The bungled upgrade and subsequent closure of the Merriwa to Willow Tree Road created an extensive detour for those travelling from one side of the Upper Hunter to the other, and added hours to the round trip to Tamworth via Scone.

"Today marks a pivotal moment for the Upper Hunter region as we break ground on the Coulson's Creek Road upgrade," Upper Hunter Shire mayor Maurice Collison said.

"This project represents the collective efforts and dedication of our community, backed by significant support from the NSW and Australian governments.

"Their support reaffirms the critical role of government partnership in driving regional growth and prosperity.

"We are committed to enhancing our infrastructure to support our community's needs today and into the future."

The road was previously completed in 2019, but the vital community connection was significantly damaged by heavy rainfall and subsequent land slips, and it was closed in 2021.

The upgraded road will feature improved drainage, protection against rock falls, new safety barriers, signage and line marking.

Hunter MP Dan Repacholi said the upgrade of the three-kilometre section of road will mean B-double trucks will once again be able to use the route.

"This provides cost savings for heavy vehicle operators and the community," he said.

Daracon Group will carry out the work, which is expected to be complete by mid 2025, weather permitting.

"It is great to see work getting under way on this important regional road in the Upper Hunter after being closed for more than three years, and to see the cooperation between the three levels of government," Federal Infrastructure, Transport, Regional Development and Local Government Minister Catherine King said.

"We know how important this road is for agriculture and livestock, providing essential access for farmers and livestock producers.

"It will also reduce travel times for all road users while improving safety by reducing traffic volumes on those roads that were being used as detours while Coulson's Creek Road was out of service."

NSW Regional Transport and Roads Minister Jenny Aitchison said "work on the road will restore an important connection between the Golden and New England highways, benefitting tourism in this beautiful part of regional NSW, logistics, distribution and supply chains."

NSW Duty MLC for Upper Hunter, Emily Suvaal described the work as "a huge win for the community".

"I commend the hard work of everyone involved in making this project happen and look forward to taking a drive myself once the work is complete," she said.