Toll road operator Transurban says widening toll roads is not the final solution to traffic congestion, and other measures will be needed.

There will come a point where toll roads in Australia’s major cities can’t be widened any more to alleviate traffic congestion.

So, Australia may have to follow the US path, where some motorists pay more to use so-called “express” lanes and toll pricing is “dynamic”, meaning it varies according to traffic conditions and adjusts to keep traffic flowing.

“It is clear that we cannot simply keep building out the (toll road) networks and adding capacity to address declining service levels for the peak periods,” chief executive of toll road operator Transurban, Scott Charlton, said on Thursday.

“In the long term, network pricing will have a place in transport policy to manage demand, promote public transport and fund upgrades of infrastructure.”

Mr Charlton told securityholders at Transurban’s annual general meeting that various pricing schemes had been introduced in cities overseas, including London, Stockholm, Singapore and Milan to reduce congestion and emissions.

Dynamic pricing was in place in a number of locations in the US, including Transurban’s express lanes project on the I-495 toll road in northern Virginia.

The I-495 express lanes project, which serves Washington DC and its suburbs, has been operating for nearly two years.

Later this year, Transurban will open its second express lanes project in the US, on the I-95 toll road, also in northern Virginia.

The I-95 express lanes will connect to the I-495 express lanes.

Vehicles carrying one or two people pay a toll to use the express lanes, while buses and vehicles carrying three or more people travel toll-free.

Express Lanes are operating in Minnesota, Florida and California.

Mr Charlton said Australia’s cities shared parallels with these urban centres in the US, with forecast congestion so severe that it would require a different way of thinking on how prices could be used to manage demand, change consumer behaviour and improve service.

Transurban has 11 roads in its Australian portfolio, including CityLink in Melbourne; the Hill M2, Lane Cove Tunnel and Cross City Tunnel, Eastern Distributor, Westlink M7 and M5 in Sydney; and the Gateway Motorway, Logan Motorway CLEM 7, Go Between Bridge and Legacy Way in Brisbane.

Transurban has upgraded the M2 and and has nearly completed the widening of the M5 in Sydney.

It has already upgraded and widened sections of CityLink in Melbourne and earlier this week signed contracts with the Victorian government for an $850 million widening of the Tullamarine Freeway section of CityLink.