Road tunnels

Watch Sydney's Air Quality-Impact of moving traffic into tunnels

There are six main tunnels in the Sydney road network - Lane Cove Tunnel (M2), Sydney Harbour Tunnel, Cross City Tunnel, Eastern Distributor, M5 East Tunnel and the newly opened New M4 Tunnel. Each of these tunnels have elevated ventilation outlets which are very effective at ejecting tunnel air high into the atmosphere through a combination of buoyancy and speed, dispersing and diluting pollutants much more effectively than surface level emissions.

Learn why we build tunnels

Download tunnels factsheet (PDF)

Monitoring emissions

Tunnel air quality is monitored 24 hours per day in all new tunnels and compiled into real-time data and historical reports. That’s 8,760 hours of monitoring a year making sure air quality meets strict guidelines.

View data

Lane Cove Tunnel -

M5 East -

New M4 -

How our tunnels work

Free flowing traffic produces fewer emissions than stop start traffic. Ventilation outlets disperse emissions high into the atmosphere away from local communities. Click to find out more below.

Artist impression of emission levels and traffic are indicative only.