Brisbane Metro CBD tunnelling to start this year

Construction on a tunnel under Adelaide Street for the $1.2 billion Brisbane Metro is expected to begin in late 2021.

The tunnel will allow the metro's electric vehicles travel along Adelaide Street, through to King George Square bus station, while avoiding above-ground buses, pedestrians and general traffic.

Its entry point at North Quay will allow buses and metro vehicles to cross the Victoria Bridge and enter Adelaide Street without meeting general traffic, after the bridge is closed permanently to private vehicles on January 24.

Lord mayor Adrian Schrinner also released new design images of the Adelaide Street boulevard, with cosmetic work slated to upgrade the street as tunnelling is underway.

"We know that Adelaide Street ... has safety issues with people crossing the road, with a large number of pedestrians, and we have announced our plans to transform Adelaide Street to a more people-friendly place, and today we're releasing the images of what it will look like post-Brisbane Metro," Cr Schrinner said.

New concept images showing the planned entrance at North Quay for the Brisbane Metro Adelaide Street tunnel.Credit: Brisbane City Council

The tunnel work will be completed by the Brisbane Metro lead consortium, Brisbane Move, and has changed its approach from a cut-and-cover design, which would have closed one side of Adelaide Street during construction, to a tunnelling design.

Neither Cr Schrinner nor public transport committee chairman Ryan Murphy, who has oversight of the project, could comment on whether the shift in construction method would increase costs.

Brisbane Move consortium partnership manager Jose Sanchez said the consortium had only briefly considered the cut-and-cover method and had not fully costed it before moving to a tunnelling approach.

Mr Sanchez said tunnelling would protect trees and landscaping on Adelaide Street, reduce interruptions for businesses and reduce congestion during construction.

The council will widen footpaths on Adelaide Street and landscape the street.Credit: Brisbane City Council

The tunnelling is expected to take about 13 months.

Cr Schrinner said any construction detours or delays would be flagged well in advance for Brisbane commuters travelling through the city during construction.

He could not say when road closures or delays might start for the first stage of tunnel construction – the entry ramp at North Quay – but said it would be an "ongoing thing".

Opposition leader Jared Cassidy said Brisbane Metro had been redesigned multiple times with additional cost added and Cr Schrinner needed to be clear about any cost changes because of design changes.

"This project only exists on paper. We've seen no work whatsoever commenced, not one shovel has hit the ground, not one boot is on the ground whatsoever," he said.

"What we need to see is this project actually get going."

The cost of Brisbane Metro has increased from $944 million to $1.2 billion, with Cr Schrinner blaming the expanding cost partly on delays as the state government had not issued early approvals in 2019, and the expense of opting for electric vehicles for the metro.

Concept images also show how Victoria Bridge will be reworked to fit two-way cycling lanes on the downstream side of the bridge, more pedestrian space, and three lanes for Brisbane Metro and buses.

The bridge will close on Sunday to all general vehicles, with only buses, pedestrians, cyclists and scooter-riders permitted to use it.

Victoria Bridge will have a viewing platform at North Quay and a two-way cycling lane on the downstream side of the bridge.Credit: Brisbane City Council

The council warned of delays of up to 20 minutes for drivers during the adjustment period, with drivers encouraged to use the William Jolly or Go-Between Bridge to access the south Brisbane suburbs.

Cr Schrinner said the closure should not be a surprise to motorists and delays were contingent on peoples' awareness of the bridge closure.

"We're expecting up to 70 per cent of vehicles that currently travel along Victoria Bridge to go via William Jolly Bridge," he said.

"William Jolly Bridge already takes significantly more traffic than Victoria Bridge does – Victoria Bridge takes up to 10,000 vehicles a day, but around 20,000 pedestrians and cyclists a day."

The lord mayor said that, on an "ongoing basis", the likely additional travel time for people entering and exiting the south Brisbane suburbs was five minutes.