The lack of any new buses comes as road traffic in and around Australia's busiest airport continues to worsen.

The gridlock prompted the Baird government to recently introduce immediate new traffic measures and urge people to travel to Kingsford Smith by train instead of car.

Roads Minister Duncan Gay put it bluntly last month when he said the situation on the roads near the airport "could only be described in technical terms as a bloody mess".

Unveiled in late 2013, the blueprint for improving Sydney's bus network included better east-west and southern links to Kingsford Smith.

Other proposals were for more buses from the inner west and Bondi Junction and Kingsford to the airport, and a new route from Chatswood via the CBD.

But it has now emerged that those policies are unlikely to be put in place before the end of the decade.

Transport for NSW said changes to the "broader south-east bus network" would happen once the $2.1 billion light rail line from the CBD to the eastern suburbs of Randwick and Kensington was running in 2019.

"This will support the introduction of extra bus services that provide more connections to and from the airport," a spokesman said.

"Commuters are encouraged to use the existing train services, which continue to provide timely, regular access to Sydney Airport."

A one-way trip on the privately owned rail line to or from the airport costs up to $17.40, making it the most expensive trip for train passengers in Sydney.

The high cost of the train is due to a station access fee of $13.40 for the airport terminals – the vast majority of which ends up in government coffers.

The aim to "improve bus access" to the airport was stage two of "Sydney's Bus Future", and was made without definitive timeframes.

Transport officials were also tasked with investigating the possibility of new links from the airport to major centres.

More than two years on, the 400 service between Bondi Junction and Burwood remains the only public service that stops at the airport's domestic and international terminals.

A clause in a contract between the government and the operator of the train line to the airport gives "protections" to the latter from a competing bus service between the CBD and Kingsford Smith.

If competing bus services began, it would most likely require the government to offer some form of compensation to the Airport Link Company.

However, it does not stop the government from starting bus services from other parts of the city to the airport.

Labor's transport spokeswoman Jodi McKay said the focus needed to switch from roads to public transport measures such as more bus connections to help solve gridlock on roads around the airport.

"It seems a no-brainer to put on more buses."

Ms McKay said the government had been eager to unveil glossy documents trumpeting a blueprint for the bus network but had not delivered on the plans.

"They are so focused on the CBD that they are forgetting that there are areas of enormous growth," she said. "They have not moved forward at all."

Emphasising that "Sydney's Bus Future" was a 20-year plan, Transport for NSW said an extra 490 services a week had been put on routes to and from Green Square in Sydney's inner south since March 2011.

In total, more than 13,000 extra weekly bus services had been introduced across Sydney since 2011.

A spokesman for Sydney Airport said it would welcome additional government bus routes to help cater for the 150,000 people who travel to and from the airport every day.

As part of a major redevelopment, Sydney Airport is building a seven-storey interchange at the domestic terminal which will include a drop-off and pick-up area for buses as large as double-deckers. Construction of the interchange is expected to be completed by 2018.

The government and Sydney Airport are about 18 months into a five-year upgrade of roads in and around Kingsford Smith at a cost of $500 million.

Corinne Mulley, the chair in public transport at the Institute of Transport and Logistics Studies at the University of Sydney, said buses provided a flexibility to public transport as their routes could change to meet new needs quickly.

However, road access to airports was always a "tricky" proposition because of the high number of travellers and workers who drove.

Professor Mulley said "Sydney's Bus Future" had been more of a "philosophical approach" to bus planning, and revolved around the idea that interchange allowed more destinations to be reached in a high-frequency network. "It has advantages in freeing up capacity," she said.