Western Sydney residents who will be forced to leave their homes to make way for the M12 Motorway say they have been left in the dark by the Government about their future.

The NSW and Federal Government today released design details of the planned M12 Motorway that, once completed, will connect motorists to Western Sydney Airport.

The NSW Government said it will be vital for a growing population in Western Sydney, an area expected to increase by one million residents in the next 15 years.

But the 16-kilometre motorway will cut through 55 properties once completed, including 15 houses, and some residents say they face an uncertain future.

Kemps Creek resident Annette Towers says the State Government is yet to tell her family when they will have to leave the property and how much they will be paid for the compulsory acquisition.

"We've got horses, so it's not just moving yourself," she said.

"We know we've gone but we don't know when and how much.

"People say 'go buy a place', but you can't go buy a place till you know how much you've got to spend."

'We're finished'

Nearby resident Frank Knapton has trained harness racing horses at his Kemps Creek property for 30 years, and has been in the industry for 50 years.

He said under the current proposal the motorway will run through the back of his property and likely prevent him from running his business.

"We're finished, if we can't train the horses, then we're finished," he said.

Residents in Kemps Creek say they are still not sure how much they will be paid for the compulsory acquisition of their properties. ( ABC News )

Mr Knapton said he is yet to receive information on whether his property will be compulsorily acquired, leaving his future at the property in doubt.

"From a personal point of view, we love living here," he said.

"But if its going to be a thing where we have a six lane highway, traffic 24-hours a day, I think that possibly we would accept it [compulsory acquisition]."

"I don't know — maybe it's time to retire."

Minister defends motorway

NSW Roads Minister Melinda Pavey said the Government would be going back to the community for more consultations after its announcement.

She said the motorway would be vital for the Western Sydney population as it expands over the coming decades.

"Over the next 20 years we expect three million more people to live in this part of Western Sydney," she said.

"This 16-kilometre motorway is going to make a considerable difference and give access to that airport the people of Western Sydney have waited so long to have."

The motorway starts at Cecil Hills and runs parallel to Elizabeth Drive, ending at the Northern Road at Luddenham.

Tolls are being considered as part of the design process, although Ms Pavey said no decision has been made.