The government's announcement on Monday means the options of a bypass, or a widening of the highway through the middle of the village, will no longer be considered.

Instead, a tunnel will be built from the Mount Boyce Heavy Vehicle Safety Station on the Lithgow side of Blackheath to either Sutton Park (the short tunnel option) or south of Evans Lookout Road (the long tunnel option).

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It's a major piece in the puzzle for the highway duplication, announced in Bathurst in the lead-up to the 2019 state election, and to which the NSW Government has committed $2.5 billion.

Member for Bathurst Paul Toole, who is the acting deputy premier and Minister for Regional Transport and Roads, said a tunnel would deliver the best result for preserving the village's character and heritage as well as smoother and safer journeys for motorists.

"This is a complex project and we wanted to work with the people who know Blackheath best to ensure we identified the best options for the community," Mr Toole said.

"For the past six months, the Blackheath Co-Design Committee - which brought together representatives from community groups, local council, emergency services and Transport for NSW - has been doing just that and has helped shape the way forward.

"We're now asking for the community's feedback on two tunnel options under Blackheath - options that will ensure minimal impacts to property, improve safety and congestion through the village and provide an alternative route for emergency services."

Mr Toole said the Centennial Pass and Station Street bypass options had been removed from consideration.

"We told the Blackheath community we would provide certainty on route options for the Great Western Highway upgrade and we are providing that certainty today," he said.

"We also want to hear from the community about other suggestions for improvements that could be made to the existing highway to improve safety and connectivity in Blackheath."

The NSW Government says tunnel options for Blackheath are still in the very early stages of strategic design as part of the Great Western Highway upgrade and Transport for NSW will continue to seek community input as designs progress.

Closer to Bathurst, the government hopes to start the $45 million upgrade of the Kelso to Raglan section of the Great Western Highway next year.

It has been delayed due to property acquisitions.