Some delays will be expected as crews undertake investigations into the road surface in an effort to obtain information for future projects.

Work will involve excavating test pits and taking samples from the road shoulders at two locations along a 14 kilometre section of highway between Orange and Bathurst.

Work will be carried out on weekdays between 7.30am and 5.30pm and is expected to take one month to complete, weather permitting.

Traffic control and a reduced speed limit of 40 km/h will be in place for the safety of workers and all motorists.

Motorists using the highway are advised to drive to the conditions and follow the directions of all signs and traffic control.

Transport for NSW has issued a thank you to motorists for their patience during this time.