Tunnel air quality

Transurban operates Legacy Way, including a tunnel linking Brisbane's inner north to the southern and eastern suburbs, in accordance with the air quality requirements set by the Queensland Government.

We’re using technology to adapt our tunnel ventilation systems to better align with traffic flow in the tunnel and allow air to be released from tunnel portals as well as ventilation outlets. Tunnel portal ventilation will only occur during off peak periods when there is less traffic on the road. These improvements will reduce energy consumption while maintaining safe air quality both inside and outside the tunnel.

The Legacy Way ventilation tunnel portals and ventilation outlets are located at Herston and Mt Coot-tha.

Legacy Way opened in June 2015 and since April 2022, ambient air monitoring is no longer required by the Department of Environment and Science. As a result, the following ambient air quality sites will be decommissioned over the next year:

  • Anzac Park, Toowong
  • Mount Coot-tha Botanical Gardens, Mount Coot-tha
  • Victoria Park, Kelvin Grove
  • Centenary Pool, Spring Hill.

Legacy Way ventilation outlet air quality monitoring is still undertaken in Herston and Mt Coot-tha.

Reports for ventilation outlet monitoring and ambient air quality monitoring are available on this website.

The in-tunnel air quality monitoring shows data for:

  • Carbon monoxide (CO)
  • Nitrogen dioxide (NO2)
  • Visibility (K)
  1. Monitoring and measuring protocols for each criteria as set out in the PIARC guidelines, as current December 2009
  2. Carbon Monoxide (CO) may fluctuate when peak traffic congestion occurs (ie traffic flows are less than 10 km/h)
  3. Visibility coefficient (K) may fluctuate with peak traffic conditions (ie free flowing traffic refers to a greater speed than 50km/hr)

The external ambient air quality monitoring shows data for:

  • Carbon monoxide (CO)
  • Nitrogen dioxide (NO2)
  • Particles less than 2.5 micrometers in diameter (PM2.5)
  • Particles less than 10 micrometers in diameter (PM10)

Ambient air quality measurements may be influenced by external events (e.g. surface roads, dust storms, fires, major construction works).

The ventilation outlet air quality monitoring shows data for:

  • Carbon monoxide (CO)
  • Nitrogen dioxide (NO2)
  • Particles less than 10 micrometers in diameter (PM10)



The data used on this page is collected by third parties using equipment which is not controlled by Transurban Queensland and as such may be subject to faults or errors by third parties, external weather or environmental events, or server access issues. The data comes directly from the air quality monitoring instruments and sensors and has not been validated.

This data may be adjusted at a later time through a standardised procedure to account for instrument errors. Once data has been validated, a validated data report are posted on the air quality reports page.