Construction will soon begin after Sydney's long-awaited second airport was finally given the green light, but passengers will likely have to drive to get there.

Despite sitting a 60km drive from Sydney’s CBD, no concrete plans are in place for a rail link to the 1800ha site at Badgerys Creek in western Sydney.

Yet Prime Minister Malcolm Turnbull described himself as “a very enthusiastic devotee” of rail infrastructure in western Sydney while addressing reporters on Monday.

“We are looking at the options for rail very, very carefully with the aim of ensuring that rail connectivity for the airport will ideally commence when the airport opens and, if not, as soon thereafter as possible,” he said.

The airport is expected to open in the mid-2020s with a single 3.7km runway, initially serving up to five million passengers a year.

That number is expected to expand to 10 million by the mid-2030s with a second runway planned for the following decades, Federal Urban Infrastructure Minister Paul Fletcher said.

Although the government is only looking at rail options at this stage, Mr Fletcher said the airport would be “rail ready”, with land set aside for a train station and a train line route.

“The Turnbull government is working with the Baird government on a scoping study into the rail needs of western Sydney … asking the questions, ‘what would the right route be for a rail connection to the airport?’, ‘when should it be built?’, ‘how much should it cost?’, ‘how should it be paid for?'”

Mr Fletcher instead emphasised plans for road transport, including the new M12 motorway, which will connect the M7 to the airport, and the expansion of The Northern Road in southwest Sydney to four lanes.

Critics, however, say the government needs to be honest and transparent about its plans for the airport.

“They’ve got to bring all the information to the table,” Western Sydney Regional Organisation of Councils (WSROC) president and Blacktown mayor Stephen Bali told ABC radio on Monday.

He said no land has been set aside outside the airport for a rail corridor to link into the airport and raised concerns about the airport’s viability.

“If the airport’s going to go ahead it’s got to be successful … at the moment there are too many shortcuts and a lack of transparency,” Mr Bali said.

Mr Turnbull rejected the idea the airport plan had been rushed through.

“The need for an airport in western Sydney has been screamingly obvious for many years,” he said.

“All the regulatory approvals are done. We are getting on with the job and this airport will be built.”

Mr Turnbull also said he is confident the plan would receive lasting bipartisan support, citing Labor’s approval of the plan.

Many others have welcomed the news, with Qantas chief executive Alan Joyce saying Sydney needed the second airport at Badgerys Creek as Kingsford Smith airport is operating at capacity.

“Sydney is already full, Kingsford Smith is full, we have called for this capacity for sometime,” he told Network Seven on Monday.

The Sydney Business Chamber in Western Sydney said the airport “couldn’t happen soon enough”.

“Western Sydney is looking forward to the opportunities an airport in the region is going to provide, such as up to 9000 jobs by 2030,” director David Borger said on Monday.

Demolition has already begun at Badgerys Creek, with the next major phase of heavy earth-moving due to begin in late 2018.