Among proposed measures to make it easier to move freight across NSW and Sydney, the trucking industry is also pushing to allow B-triples on the Pacific Highway between Sydney and Brisbane, but at this stage the government is resisting.

But the government is considering clearing some major Sydney streets of parking to make it easier for trucks to use them. These include King Georges Road in the city's south-west and Botany Road in the inner-south.

The trial of B-triples on the Hume Highway is set to start once a bypass of Holbrook, south of Canberra, is finished in the middle of next year, and other works, such as larger truck-stops, can be built.

According to the trucking industry and the government, the advantage of B-triple trucks - which comprise three semi-trailers behind the prime mover or cab - is that they can carry more goods than standard semi-trailers or B-doubles.

This means there could potentially be fewer trucks on the road with the use of the B-triples, which are 6½ times the length of a Holden Commodore.

''There are enormous advantages in allowing these vehicles on the Hume once the Holbrook bypass is complete,'' said the communications manager of the Australian Trucking Association, Bill McKinley.

B-triples tend to be newer than smaller vehicles, and are fitted with safety features such as a blind-spot radar.

''We have an excellent understanding of how they handle,'' Mr McKinley said. ''The safety and productivity case for bringing them in is compelling.''

The association's NSW manager, Jodie Broadbent, said the industry had started discussions with Roads and Maritime Services about a trial of B-triples on the Pacific Highway.

But she said those discussions were ''still at very early stages - it could be two or three years before we get anywhere near to doing anything like that''.

A spokeswoman for the Roads Minister, Duncan Gay, said the government was looking at a trial of the B-triples only on the Hume Highway - not on the city streets or on the Pacific Highway. The spokeswoman said a business case would be prepared in the first half of the year on allowing ''higher productivity vehicles'' on the Hume Highway, but it was unlikely a trial could begin next year.

''Allowing HPVs on the Hume Highway between Sydney and Melbourne could cut the number of freight trucks needed to service the growing road freight task,'' the spokeswoman said.

''On initial estimates, this could result in almost a million less B-double equivalent trips over a 30-year period.''

The government's draft freight strategy, released late this year, revealed it is considering reviews of parking on major roads used by many trucks.

Labor's roads spokesman, Ryan Park, said he was not concerned about a B-triple trial on the Hume Highway, but would be worried about where they were allowed to go to in Sydney. ''They're obviously not vehicles suitable for suburban roads,'' Mr Park said.

The Greens transport spokeswoman, Cate Faehrmann, said the trial represented short-term thinking that would lead to even bigger crashes.

''With the release of this plan, Duncan Gay's new title should be the Minister for Monster Trucks,'' Ms Faehrmann said. ''Clearly his vision for NSW is a tangle of congested motorways and trucks on steroids.''