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
Roads and Maritime Services adheres to strict conditions set down by the NSW Department of Planning and Infrastructure for the maximum allowable presence of vehicle emissions in the air both in and outside its 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.
Australian ambient (outside tunnel) 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.
Australia's ambient air quality standards are among the strictest in the world. The regulation and management of air pollution in Australia has meant that our air quality has been steadily improving since the 1980s. A recent study by the World Health Organization shows that Australia has some of the cleanest air in 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.
The new Sydney Air Quality Improvement Program (SAQIP)
In June 2012, Roads and Maritime Services reinforced its commitment to monitoring and managing air quality in Sydney by implementing a new plan, known as the Sydney Air Quality Improvement Program (SAQIP).
SAQIP will adopt a broad-reaching approach that works to reduce the impact of the existing older heavy diesel trucks on both the M5 East tunnel and elsewhere.
Upgrading the smoky vehicle camera system, and expanding the diesel retrofit program, means RMS is continuing with alternative methods to reduce NO2 and PM in both the M5 East tunnel and the broader Sydney road network.