Sydney motorists will soon be sharing the roads with 30-tonne trucks making about a million trips to and from major transport construction sites, carting dirt and rock.

The state government has kick-started a rash of multi-billion dollar tunnel projects, all pitched at combatting the city's crippling congestion.

Construction congestion: Trucks are likely to become increasingly common on Sydney's roads, transporting waste from the city's infrastructure projects. Credit:Jim Rice

But until they are built, many of Sydney's busiest roads will be filled with trucks carting the spoil from the three longest road and rail tunnels ever built in the city.

According to figures from the environmental impact statements for the north-west rail link between Epping and Rouse Hill and the NorthConnex motorway under Pennant Hills Road, and extrapolated for the WestConnex motorway, about 10 million cubic metres of rock and dirt will be dug up from under Sydney within the next eight years.