A PLAN to build motorways across the west, inner west and south of Sydney is a throwback to 1950s transport planning that will quickly lead to congested roads, says one of the state’s most respected transport figures.

In rare public comments, the former chief road builder and rail bureaucrat, Ron Christie, has delivered a scathing critique of the plan being proposed by the head of Infrastructure NSW, Nick Greiner, as part of its 20-year strategy for the state released this month.

Mr Christie’s critique argues the strategy includes no plan to allow commuters to switch between the new M4 and M5 motorways and public transport. It also says the plan for the train system is deficient. ”What is plan B when both the M4 and M5 run full in a few years’ time after completion?” Mr Christie said.

His comments carry the rare authority of one who has led the state’s road and public transport arms. As a former chief executive of the Roads and Traffic Authority, he led the construction of the Eastern Distributor.

He also oversaw the widening of the M4 from four lanes to six between Penrith and Westmead before the Olympics in 2000. After the M4 was widened, it immediately became clogged again.

”That example indicates that without other measures, just taking a roads approach to the problem is doomed to fail,” he said. ”It is back to the 1950s. It is a real LA-type solution.”

The state infrastructure strategy was built around new M4 and M5 motorways – dubbed WestConnex – to run through inner west and southern Sydney.

The government has since adopted the project but is yet to respond to Infrastructure NSW’s other suggestions.

Infrastructure NSW, chaired by Mr Greiner, a former premier, argued against adding new lines to Sydney’s train network beyond the south-west and north-west rail links already under development.

Infrastructure NSW argued that most journeys in Sydney were by car, therefore the city needed more motorways before new public transport projects.

But Mr Christie said that without investment in public transport, roads would inevitably become clogged. There was no plan to allow motorists to use the new motorways then change to public transport. The plan offered little detail on how to deal with congested traffic coming off the motorways.

”The report attempts, but not convincingly, to mount the argument that motorway extensions towards centres of activity do not in themselves attract more private transport,” Mr Christie said.

”Experience is that they do, especially if there is a failure to develop a high-class public transport alternative.”

Mr Christie was also the co-ordinator-general of rail and ran transport operations during the Olympics. He has not commented on transport issues since chairing the Herald’s independent transport inquiry in 2009-10.

He said the motorway plan condemns drivers to sharing road tunnels with large trucks heading to and from Port Botany.

”The mixing of trucks and private vehicles in a confined tunnel increases safety risks but also presents ventilation challenges,” he said. Infrastructure NSW could have considered a separate truck tunnel for the eastern extension of the M5, he said.

A spokeswoman for Infrastructure NSW said: “Mr Christie is entitled to his opinion but the state infrastructure strategy is all about generating fresh ideas, fresh thinking and moving on from past failures.”

She said the strategy did offer ways to reduce congestion near the airport and Port Botany, and options for interchanges between WestConnex and public transport would be considered as part of detailed project development in coming months.