More than 50 northern Sydney properties could be demolished to make way for the proposed NorthConnex motorway link but the NSW government says it’s too early to say how much compensation will be paid.
Construction on twin tunnels to link the M1 and M2 motorways will start next year and the road link is scheduled to be open to motorists by 2019.
On Tuesday a spokesman for Roads Minister Duncan Gay confirmed some property would need to be acquired for the $3 billion project and a question mark now hangs over 52 commercial, industrial and residential properties.
The properties are along the route and are needed for main work sites at the portals, the intermediate plant areas and where existing roads need to be modified, he said.
"While building a tunnel requires less property acquisition than a surface motorway, some property will need to be acquired for this project," the spokesman said on Tuesday.
"It is too early to determine the level of compensation required - the project team is committed to working closely with those affected to allow the necessary acquisition to be progressed ahead of work starting in 2015."
A list of frequently asked questions prepared by NorthConnex in December says a "compulsory acquisition process may be required to complete surface acquisitions whereby agreement cannot be reached with the owners".
Those whose own properties that may be affected have been recently contacted.
A NorthConnex plan released over the weekend for consultation shows one ventilation unit at West Pennant Hills and another at Wahroonga.
Mr Gay's spokesman said the final design and height of the stacks would be determined during the environmental assessment and displayed for public feedback in May.