An extension of Westconnex due to open early next year will link Sydney's west with the airport by joining the existing M4 and M8 tunnels.
The new section of tunnel runs for 7.5 kilometres between St Peters and Haberfield, bypassing up to 52 sets of traffic lights and cutting peak hour travel times from Parramatta to Mascot by up to 40 minutes.
Members of the community were invited to tour the tunnel by bus on Sunday and were thanked for enduring four years of construction disruptions.
Transurban Group Executive for WestConnex Andrew Head explained the final steps before the tunnel opens some time in the first quarter of next year were to test its software operating system.
"The concrete and the steel has been laid, but what we're doing at the moment is we're testing the tunnel," Mr Head said.
"We've got ventilation systems, we've got lights, we've got cameras, we've got speakers, all the various different things that you need to ensure a safe journey."
Passenger vehicles will pay $5.65 to use the new section of tunnel, which is a distance-based calculation, capped at $10.47 across the entire 22 kilometre network.
Heavy vehicles will initially pay $16.95 for using the new section.
Motorists were urged to visit the Westconnex website ahead of driving in the tunnel for the first time to avoid early navigation issues.
Chief operations officer at Transport NSW, Howard Collins noted the Westconnex website included a tool allowing drivers to virtually plan their route.
"In the comfort of your own armchair at home you can travel this route looking at a virtual experience," Mr Collins said.
"It is so important to make sure you know the route you're taking."
Project director at Transurban, Terry Chapman said the tunnel was the safest in the world as he thanked the more than 12,000 people who worked on the project at various times.
"This asset is just really world class and it's a real credit to the designers and all the people who worked on the tunnel," Mr Chapman said.
One of the newer safety innovations is an automated incident vehicle protection system, which can tell when a vehicle stops or reverses in the tunnel and can communicate with the driver or contact emergency services if necessary.
"There's a number of different systems that relate to fire, that relate to observing traffic, identifying incidents and dispatching people to respond to those incidents as quickly as we possibly can," Mr Head said.