Sydney road tunnels
The Sydney Orbital Network includes over 160 kilometres of surface roads, tunnels, bridges and underpasses.
There are five main tunnels along the network; Lane Cove Tunnel, Sydney Harbour Tunnel, Cross City Tunnel, Eastern Distributor Tunnel and the M5 East Tunnel.
Air quality in and around road tunnels
Air quality monitors in and outside the tunnels constantly measure the presence of carbon monoxide, nitrogen dioxide, fine particles and visibility levels.
External air quality in the suburbs adjacent to tunnels will vary during the year due to seasonal climate variations, wind speeds and external events such as dust storms, bush fires and construction works in the area.
Australia’s ambient (outside) air quality is regulated according to standards set under the National Environment Protection Measure: Ambient Air Quality. These standards were commissioned by the National Environment Protection Council.
The regulation and management of air pollution in Australia has meant that our air quality has been steadily improving since the 1980s. Data from the World Health Organisation shows that Australia has some of the cleanest air in the world, see how Sydney compares to the world.
In-tunnel Air Quality (Nitrogen Dioxide) Policy
In January 2016, the NSW Government released a policy for emissions compliance in new tunnel projects to protect the health and safety of tunnel users.
The In-tunnel Air Quality (Nitrogen Dioxide) Policy sets a limit of 0.5 ppm for nitrogen dioxide emissions in all new tunnels more than one kilometre long to ensure air quality continues to improve over time.
An in-tunnel nitrogen dioxide compliance standard of 0.5 ppm - as a 15 minute rolling average across the whole tunnel – sets the benchmark in Australia and compares favourably to the international in-tunnel nitrogen dioxide design guidelines which range between 0.4 ppm and 1 ppm.
Motorists travelling in all tunnels are encouraged to turn on headlights, wind up windows and use air conditioning on recycle to regulate air inside the vehicle.