MORE than 90 properties on the north west rail link route will be bought and demolished as the state government forges ahead with the city’s biggest transport project since the Sydney Harbour Bridge.

Business will be disrupted and residents will be subjected to noise, vibration and traffic during the five-year works, the scale of which was revealed yesterday when the first environmental impact statement was released.

Two-thirds of the $9 billion, 23-kilometre line will be built underground between Bella Vista and Epping.

The tunnels will be the deepest in Australia, dipping to 70 metres below the surface.

Most of the remainder of the line will be ground level with a four-kilometre elevated ”skytrain” between Bella Vista and Rouse Hill.

About 60 homes, 30 businesses and two other properties will be compulsorily acquired to allow for construction.

At Cherrybrook, 28 homes will be demolished to make way for a new station. The Hills Centre station at Castle Hill will require 11 businesses to go, and another seven properties will be resumed on Windsor Road near Kellyville Ridge.

A spokesman for the north west rail link said the government understood compulsory property acquisition ”can be a difficult time for many people”.

”At all times, [we have] been in close communication with people affected by the project and offered assistance to make the process as straightforward as possible,” the spokesman said.

The Hornsby Shire mayor, Nick Berman, said some homeowners were concerned at moves to buy them out, but most people understood the ”big picture” benefits.

”There is always going to be some people who wouldn’t have planned to move out, and no amount of money will totally satisfy them, but I think it will be the minority,” he said.

Tunnelling will take place 24 hours a day, seven days a week. Above-ground construction work, including eight new stations, will mostly be during daylight hours, Monday to mid-Saturday. Residents and institutions along the line from Epping to Rouse Hill will be affected by construction, including the Hillsong Church at Baulkham Hills, Beecroft Primary School and the Koala Park Sanctuary at West Pennant Hills.

Measures such as noise barriers and acoustic sheds will be used to minimise noise.

About 2.4 million cubic metres of earth will be excavated during the project, creating truck movements and additional noise.

The project will require small areas of endangered ecological communities to be removed, including Cumberland Plain Woodland and potential habitat for six listed species of flora and nine listed fauna species.

Businesses in the Hornsby Shire, Hills Shire and Blacktown City will be affected by reduced access and visibility, noise and vibration, but will benefit from increased trade and other income flowing from construction.

The project is expected to support more than 16,200 construction jobs and inject $25 billion into the NSW economy.

The link will provide 300,000 residents in north-western Sydney with rail access to destinations such as Epping, North Sydney and the Sydney central business district.

The environmental impact statement will be on display until May 21.

A second statement including the design of stations, other rail infrastructure and signalling systems will be released later this year.

Tunnelling is expected to start in 2014, and trains are due to run by 2019.