The Illawarra Highway between Yellow Rock Road and Jamberoo Mountain Road at Macquarie Pass remains closed in both directions on Sunday morning, and could stay closed for weeks.

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Emergency investigation work was conducted last week due to recent rainfall, with further geotechnical inspections carried out late Saturday afternoon.

Inspections identified slope movement and extension of cracks in the road surface, resulting in the road closing at 7.30pm Saturday.

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Transport NSW has said monitoring and assessment work will be carried out over the next week, with repair work anticipated to start on Monday April 4, weather permitting.

"This section of road will remain closed until work is complete," they said in a statement. "Work is expected to take several weeks, weather permitting."

Detours for light vehicles will be in place via Jamberoo Mountain Road, adding an additional 10 minutes to travel times.

Vehicles over 7.5 meters or 12 tonnes will need to detour via Hume Motorway, Picton Road and M1 Princes Motorway, adding up to an additional 30 minutes to travel times.

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Property access will be maintained throughout the work via the eastern or western access points. No access will be permitted through the work site.

Motorists are advised to drive to the conditions, follow the directions of signs and traffic control.

Transport for NSW thanks road users for their patience during this time.

For the latest traffic updates download the Live Traffic NSW App, visit livetraffic.com or call 132 701.

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