Once completed, they are set to more than quadruple the length of the city’s mostly tolled underground road network.
“We are only going to get a taste of the power of WestConnex with the opening of this part,” Transport Minister Andrew Constance said.
The opening of the M4 East, which runs as twin three-lane motorway tunnels from Homebush to Haberfield, will be the first major test of whether the $16.8 billion WestConnex project lives up to the promise of reducing congestion on free arterial roads.
The Transport Minister predicts it will cut travel time by up to 20 minutes for motorists travelling to the city from western Sydney and the wider WestConnex project had the ability to transform communities.
“It will take 10,000 trucks a day off Parramatta Road. We are going to see a very different outcome for the road network,” he said.
But experts say there is much riding on the M4 East influencing public perceptions of WestConnex.
Martin Locke, an adjunct professor at the Institute of Transport and Logistics Studies at the University of Sydney, said traffic from the new road tunnels from Homebush to Haberfield was likely to increase flows of traffic onto local roads and the Anzac Bridge until the third stage of WestConnex – tunnels linking the extended M4 and M5 – was completed in 2023.
“There is the potential for a bottleneck around the end point of the M4, and a tailback into the tunnels. So rather than relieve congestion, you could increase congestion in the short term,” he said.
“The real relief will only come from the third stage. But that will be for the cars or trucks which want to go in the direction of the airport and the M5.”
The government decided against a month-long toll-free period for the M4 East because it wanted to avoid severe congestion at interchanges and entrances and exits from the new tunnels.
And it has warned motorists of potential congestion hotspots at an interchange at Concord where the new motorway connects to Parramatta Road and the widened M4, as well as at exit ramps from the new tunnels to Wattle Street at Haberfield and the City West Link.
The maximum toll on the new tunnels is $4.27, while the total cost of using the length of the new M4 from Parramatta to Haberfield is $7.89 each way.
Meanwhile, the Inner West Council has called on the government to spend $30 million on traffic calming measures to stop motorists from speeding through local streets on “rat runs” as they seek to avoid tolls.
“Expert traffic analysis shows that when stage one opens it is going to create the mother of all rat runs through local streets,” Inner West mayor Darcy Byrne said.
Mr Locke, a former investment banker and infrastructure adviser, said any congestion at exits from the M4 East tunnels was likely to put pressure on the state government to proceed with the Western Harbour Tunnel because it was designed to relieve bottlenecks for northbound traffic.
“Until all of these toll roads are built, you are not going to know whether [WestConnex] is a congestion buster,” he said. “Let’s not jump to hasty conclusions but our patience might be tested several years out into the future.”
Under the plans, WestConnex will connect to the Western Harbour Tunnel at an underground interchange at Rozelle.
But the $14 billion tunnel under Sydney Harbour and so-called Beaches Link to the north-east remains largely unfunded and is not due to be completed until the middle of the next decade.
Sydney already has more kilometres of toll roads above and below ground than any other city in the world – a situation that is set to grow significantly over the next five years.
By 2023, the city will have 12 toll roads including the final stages of WestConnex and NorthConnex. A year later, the first stage of a tolled extension of the F6 motorway in Sydney’s south is due to open at a cost of up to $2.6 billion, followed by the Western Harbour Tunnel and Beaches Link tollway.
Leaked documents marked “cabinet in confidence” have previously revealed the government has looked at $3 tolls for cars on northbound journeys of the Sydney Harbour Bridge and Harbour Tunnel to help pay for the $14 billion cost of the Western Harbour Tunnel and Beaches Link.
It has also been proposed that tolls be placed on southbound journeys on the Eastern Distributor.
Matt O’Sullivan is the Transport Reporter for The Sydney Morning Herald.
Ben is a journalist for The Sydney Morning Herald.