The M5 tunnel has been shut eastbound with one lane closed westbound close to Sydney Airport.
A “large quantity of hazardous oil” has been spilled, with experts from Fire and Rescue NSW working to contain it.
Environmental experts are also on the scene.
The crash has also damaged the fire sprinkler system and tunnel wall.
“This crash has taken out the critical fire suppression system in the tunnel,” Superintendent Adam Dewberry from Fire and Rescue NSW said.
As a precaution, firefighters will position two fire trucks at the end of the tunnel in case of a fire, he said.
Dewberry said crews are working to get westbound traffic moving.
They’re also grappling with getting the vehicle out.
Citybound commuters heading east face a longer wait.
”It is looking like it will take some time for eastbound,” Dewberry said.
The driver got out after the crash and only suffered minor injuries.
Motorists can also consider exiting earlier at the King Georges Road off-ramp to detour along the D5.