The new 50-metre bridge is part of the $3 billion NorthConnex project that will improve travel times into Sydney.
Minister for Transport and Infrastructure Andrew Constance said motorists approaching the M1 Pennant Hills Road intersection would now be directed onto a new 400-metre lane.
“By relocating southbound traffic, the construction team are able to continue to excavate the new tunnel entry and exit points beneath the bridge without disruption to M1 motorists travelling above,” Mr Constance said.
“The bridge has quickly taken shape in the last few weeks with asphalting, barrier installation and line marking, while work to build the new Northern Interchange is also progressing at pace.”
NorthConnex is a nine-kilometre tunnel that will link the M1 Pacific Motorway at Wahroonga to the Hills M2 Motorway at West Pennant Hills.
Once the project is complete, it will take around 5000 trucks off Pennant Hills Road each day and return Pennant Hills Road to local traffic.
Motorists using the tunnel will save up to 15 minutes travel time by bypassing up to 21 traffic lights along Pennant Hills Road.