WestConnex underground motorway tunnels are wider, flatter and higher than most other tunnels in Sydney, meaning a smoother journey with less stop-start driving and fewer vehicle emissions – including greenhouse gases.
In fact, by 2021, WestConnex will reduce carbon dioxide (CO2) emissions by more than 610,000 tonnes. By 2031 this rises to 1,417,420 tonnes.
Air quality assessments included in the M4 East and New M5 Environmental Impact Statements show that regional air quality is unlikely to change as a result of WestConnex. In fact, WestConnex will result in improvements in some areas where traffic uses the underground motorway tunnels instead of surface roads.
In 2017, Sydney Motorway Corporation (SMC) established the Air Quality Community Consultative Committee (AQCCC) for the M4 East (Stage 1) project and the New M5 (Stage 2) project. Further information on the New M5 AQCCC is available here.
WestConnex tunnels use longitudinal ventilation systems, which require vehicles to draw in fresh air. The air from the tunnel is then released through ventilation facilities, supported by fans, which control air movement within the tunnel. The ventilation system is automatically controlled using real-time traffic data – taking into account traffic mix and speed, plus feedback from air quality sensors in the tunnel.
Usually each tunnel has a ventilation facility at the beginning and end, with up to three for each section. The exact number is confirmed during design. See our interactive map for details.
Monitoring around existing ventilation facilities in Sydney shows that these have no significant impact on local or regional air quality. See our air quality fact sheet for details.
WestConnex uses state-of-the-art ventilation and tunnel design to meet stringent air quality standards in the tunnels and the surrounding community. Filtration is not used in other road tunnels in Australia and is not needed as it would not provide any measurable improvement to the air quality in the surrounding community.
All Sydney road tunnels have management plans that involve 24-hour-a-day monitoring of tunnel air quality to ensure they are complying with independent pre-determined guidelines for in-tunnel air quality.
- Local (ambient) air quality will be monitored for at least 12 months before the tunnel opens to traffic and for at least two years after opening.
- Air quality inside the road tunnels will be monitored to ensure strict standards are met.
- Monitoring results will be made publicly available and will be independently audited.
For more information about tunnels and air quality visit Roads and Maritime Services’ website.
During the planning and assessment phase of WestConnex projects, we undertake air quality monitoring in areas near the project corridor to measure current air quality.
This air quality monitoring information is supplemented by data collected from other monitoring stations operated by NSW Department of Environment and Heritage, and is used in developing the Environmental Impact Statements for WestConnex projects.
Air quality stations currently operating
We currently have air quality monitoring stations located at Ramsey Street in Haberfield, the City West Link in Rozelle and St Peters Public School in St Peters. These sites have been established to help design and plan for WestConnex M4–M5 Link.
Air quality specialists have been commissioned to operate and maintain the monitoring network to Australian standards and guidelines.
Specific pollutants are monitored and reported against the National Environment Protection Measure (Ambient Air Quality). Meteorological conditions are also monitored locally to see their effect on air quality.
For more information, see Ambient air quality monitoring methodology and criteria - October 2015.
Key results from the monitoring of air quality during the planning and assessment phase of the M4 East, New M5 and M4–M5 Link are listed below:
- Air quality report - M4 East August 2015 (PDF, 861KB)
- Air quality report - M4 East July 2015 (PDF, 814KB)
- Air quality report - M4 East June 2015 (PDF, 835KB)
- Air Quality Report - New M5 June 2016 (PDF, 983KB)
- Air Quality Report - New M5 May 2016 (PDF, 1.02MB)
- Air Quality Report - New M5 April 2016 (PDF, 1.31MB)
- Air Quality Report - New M5 March 2016 (PDF, 1.3MB)
- Air Quality Report - New M5 February 2016 (PDF, 2.1MB)
- Air Quality Report - New M5 January 2016 (PDF, 2.13MB)
- Air Quality Report - New M5 December 2015 (PDF, 1.42MB)
- Air Quality Report - New M5 November 2015 (PDF, 2MB)
- Air Quality Report - New M5 October 2015 (PDF, 3.5MB)
- Air Quality Report - New M5 September 2015 (PDF, 928KB)
- Air Quality Report - New M5 August 2015 (PDF, 1.1MB)
- Air Quality Report - New M5 July 2015 (PDF, 830KB)
- Air Quality Report - M4-M5 Link April 2016 (PDF, 731KB)
- Air Quality Report - M4-M5 Link May 2016 (PDF, 833KB)
- Air Quality Report - M4-M5 Link June 2016 (PDF, 1.23MB)
- Air Quality Report - M4-M5 Link July 2016 (PDF, 1.40MB)
- Air Quality Report - M4-M5 Link August 2016 (PDF, 1.19MB)
- Air Quality Report - M4-M5 Link September 2016 (PDF, 1.23MB)
- Air Quality Report - M4-M5 Link October 2016 (PDF, 1.52MB)
- Air Quality Report - M4-M5 Link November 2016 (PDF, 1.23MB)
- Air Quality Report - M4-M5 Link December 2016 (PDF, 1.26MB)