Construction of a new, more durable crossing at Mitchells Causeway is to begin in July with the road expected to reopen in the second quarter of 2027.

The NSW Government announced a successful contractor - and an expanded package of support for local businesses affected by the Great Western Highway closure at Lithgow on Friday.

Following an accelerated procurement process, Seymour Whyte has been selected to construct a new crossing that will restore the connection between the Blue Mountains and Central West while improving its long-term resilience.

Extensive geotechnical investigations carried out over the past few months were critical to the procurement process, providing the evidence needed to develop the proposal for the safest and fastest reopening.

The investigations confirmed the bedrock beneath Mitchells Causeway remains stable, enabling a design that builds on the existing crossing, rather than replacing it entirely.

The new crossing will see a bridge structure built over the existing Mitchells Causeway, supported by deep piles anchored into the stable bedrock below.

The new structure will sit above, but independently of the convict-built causeway, which will be stabilised as part of the work.

Minister for Roads, Jenny Aitchison acknowledged how difficult the closure had been on families, businesses, freight operators and everyone who relied on the road.

“Today's news will not be easy to hear. I know it will mean sitting down at the kitchen table, working out how your family moves around and what the next year looks like in practice," she said.

“But I want to reinforce what this also means: we have a timeline, contractor and major construction on the new crossing beginning in July.

"In tandem, the detour routes are being upgraded to make your journeys safer and easier going forward.

“In 109 days, we have completed thorough geotechnical testing, convened a global industry roundtable, run an accelerated procurement process with leading Australian and international engineering experts, and finalised both the contract and the solution to reopen this road."

While the priority is restoring this vital transport link as quickly and safely as possible, the new crossing has also been designed to meet the region's future needs, the government's media release said.

It will be capable of accommodating an additional lane in the future, something that was never possible with the existing roadway.

Major construction will begin as soon as possible in July, with specialist engineering and construction teams undertaking drilling, grouting and heavy piling activities to establish the deep foundations that will support a new, reliable and resilient crossing.

Transport for NSW will continue to provide the community with regular construction updates as work progresses on the new crossing.

The government also announced an additional $20 million funding package which will increase the financial support available to small businesses most acutely affected and expand the number of businesses eligible for this financial assistance.

It includes grants of up to $25,000 for small businesses experiencing financial hardship in Mount Victoria, Hartley, Little Hartley and Hartley Vale; and expanding support to eligible businesses experiencing financial hardship to a wider area including suburbs in Lithgow, Oberon and Blackheath for grants of up to $10,000.

More information on eligibility criteria and application process through NSW Rural Assistance Authority is available at: https://www.raa.nsw.gov.au/grants/gwh

The NSW Government is also working with the organisers of major upcoming events in the region to minimise the impacts of the closure while construction of the new crossing is underway.

The uplift in public transport services, including extra rail, coach and bus services for Blue Mountains and Central West communities will continue for the duration of the closure.

Minister for Regional NSW, Tara Moriarty said the $20 million package would expand assistance to more businesses and increase grants for those hardest hit.

“By increasing grants in the most affected areas and introducing further support for additional communities, this will go towards helping businesses through this challenging period," she said.

“Alongside financial relief, we are maintaining public transport services and working with major event organisers to keep communities connected while construction progresses toward reopening this critical route.”

NSW Transport Secretary, Josh Murray said:

"I'd like to acknowledge the construction and engineering industry for embracing a new, faster way of working. Their expertise and willingness to collaborate has enabled us to move quickly while undertaking the rigorous investigations and planning needed to get this right.

“While construction is underway, we'll continue supporting communities through enhanced public transport services, free coaches, $50 million in ongoing upgrades to detour routes and round the clock emergency focus, making sure people and freight can keep moving while this critical work is delivered."