A new 46-metre vehicle underpass is now open under Mount Street at Northern Sydney, creating a new southbound route to the city via the Cahill Expressway for 10,000 motorists a day.
The underpass will provide a dedicated citybound connection for motorists travelling from the Warringah Freeway to the City East, airport and eastern suburbs, reducing congestion and making journeys safer and more reliable for the community.
The Warringah Freeway is an enabling project for the Western Harbour Tunnel, the first new harbour crossing in 30 years. Together they will create a game-changing link between Sydney’s north, west and airport precincts.
The underpass will remove the need for thousands of buses and general traffic to weave and merge, when the dedicated southbound bus lane opens next year, giving bus users a direct and uninterrupted journey down the freeway to the city.
To get to the Cahill Expressway, drivers will need to keep left on the Warringah Freeway and take the newly opened section of the Kirribilli exit (Alfred Street North) to access the Mount Street underpass. Signage will guide drivers.
Motorists who miss the turn off should continue to the Sydney Harbour Bridge and detour through the CBD, via the Grosvenor Street exit, Bridge Street and Macquarie Street to the Eastern Distributor.
The digging of the underpass was unique for this project. Advanced mining technology in the shape of a remote-controlled, unmanned, hard rock continuous miner, was used to carve through sandstone and rock, excavating more than 3,000 cubic metres. The method was used as it minimises noise, reduces disturbance compared to other means and was faster than traditional rock hammering.
The underpass was built ‘upside down’ next to live traffic lanes using a technique where the roof of the new structure was built first. This meant pedestrians were still able to use Mount Street while the tunnel was excavated, rather than having to detour.
The Warringah Freeway is one of the busiest roads in Australia, with around 250,000 vehicles and 150,000 bus passengers using it each day.
NSW Minister for Roads, Jenny Aitchison, said that the infrastructure being completed on the Warringah Freeway Upgrade is coming thick and fast.
“The Mount Street underpass is the latest, vital piece of the Warringah Freeway puzzle which will help to make the Freeway more reliable and efficient, and an easier and safer road to drive on,” Aitchison said.
“More than 10,000 cars a day will use the underpass and take advantage of the benefits it will deliver.”
