By Jacob Saulwick
After more than three years of construction and decades of debate, Sydney's M4 East tunnels opened to motorists in the early hours of Saturday - but the road will not face its first major test until Monday morning.
The early section of the WestConnex motorway, which in time will extend for 33 kilometres, runs between Homebush and Haberfield and attracts a maximum toll of $4.27 one-way.
Motorists use the WestConnex M4 East tunnels soon after opening Credit: Screenshot
Traffic was scarce between 2am and 3am when the eastbound and westbound sections of the M4 East, which runs largely underneath Parramatta Road, first accepted motorists.
But that situation is certain to change on Monday morning.
"It's all about familiarity," Marg Prendergast, coordinator general at Transport for NSW, said.
"We know that when any new piece of infrastructure opens its going to take people a bit of time to familiarise."
According to Ms Prendergast, there was a risk that when the first peak hour volumes arrived on Monday, eastbound traffic could bank up inside the tunnels.
“The cars will get there faster by travelling through the tunnel and they are going to join what is already a congested area," she said.
There are two eastbound exits from the tunnel - at Parramatta Road, Ashfield, and at Wattle Street in Haberfield.
As well as confronting congested roads, motorists leaving these exits will also need to be alert to potentially tricky "zipper" merges, which occur when a motorway lane combines with a surface lane.
“The rule is really quite simple: you give way to the car ahead of you," she said.
To assist with the merges, Transport for NSW has slowed the tunnel exit speeds to 60 km/h. The speed limit may be lifted to the tunnel speed limit of 80 km/h in the coming weeks.
The tunnels were officially opened, with a ribbon-cutting, on Friday.
"I can’t wait for residents and especially those in western Sydney who travel those long distances to get the benefits of this wonderful project," Premier Gladys Berejiklian said during that opening event.
Tunnelling started on the twin M4 East motorway tunnels in mid-2016. The tunnels contain three lanes in each direction.
A convoy passes through at the opening to traffic of the M4 East tunnels at 2am on Saturday.Credit: Nine
Later sections of the WestConnex motorway will extend them to an interchange at Rozelle, and also south under the Inner West to Tempe and the M5 East to Sydney's south-west.
The government has consistently said that the full benefit of the WestConnex motorway would not be realised until the entire project is constructed in about 2023. Until then, traffic is likely to build up around sections that have opened.
"It really is until we get M4-M5 link, Rozelle Interchange and then ultimately Western Harbour Tunnel," Ms Prendergast said.
"The bottleneck moves as we open these sections. And that’s what happens."
The M4 East, once known as the F4, has been on the planning books for decades. The road was proposed as a surface motorway that would have run from Strathfield through Five Dock, Leichhardt and Glebe until former premier Neville Wran cancelled that project in 1977, selling the road corridor.
Meanwhile WestConnex is proposing geotechnical drilling in Sydney Park, near the St Peters road interchange currently under construction. The City of Sydney Lord Mayor, Clover Moore, a fierce critic of the motorway, said it was "outrageous" that the project could further impact on the inner city parkland.
But a Transport for NSW spokeswoman said the work was temporary, would not remove any vegetation, and would not leave a long-term impact.
"We appreciate the community’s patience while this low impact work is carried out," the spokeswoman said.