The RTA will shortly start operation of the M5 East Tunnel filtration trial in the westbound tunnel. The filtration trial is part of the M5 East air quality improvement plan and aims to reduce haze in the tunnel. This plan is already showing positive results.
In 2008 the RTA responded to community requests to examine possible air filtration systems in the eastbound tunnel. In response, the RTA agreed to investigate the feasibility of installing filters into the existing cavities within the tunnel ceiling. In December 2008 the RTA invited registrations of interest from companies around the world to submit their concepts.
The RTA worked closely with the community group Residents Against Polluting Stacks (RAPS) to establish and agree to a strict set of functional and technical requirements for the proposal, as well as the installation and maintenance requirements. The key requirements included:
- No physical modification of the tunnel or jet fan niche structures.
- No significant construction work within the tunnel (which would affect tunnel availability).
- Compatibility with available power and water supplies.
- Compatibility with current M5 East tunnel ventilation systems.
- No more than 3 nights tunnel closures per month for operational maintenance.
- Treatment of 100 – 140m3/s of tunnel air.
- Minimum 90% reduction in PM10 and PM2.5 particulate matter.
- Real time data measurement and recording of data.
- Control systems integrated with existing M5 East tunnel control systems.
- Minimum 23 hours per day operation.
- Noise levels less than 85 dBA.
Six proposals to install filtration equipment into the roof of the eastbound tunnel were received. Companies from Australia, Austria, Norway and South Korea responded.
- Aigner GmbH and Aigner Tunnel Technology GmbH (Austria),
- Anderl Holding AS and Clean Tunnel Air International AS (Norway),
- Indigo Technologies (Australia) Pty Ltd (Australia),
- Puriscience Pty Ltd (Australia),
- RITCO and Daewoo International Corporations (South Korea) – two separate filtration concepts were jointly lodged.
Outcome of the assessment of proposals
None of the applications appropriately satisfied all the assessment criteria established by the RTA and RAPS.
It was hoped that a company could develop a system that could fit inside the existing tunnel roof space. However all submissions required significant excavation work in the tunnel.
Furthermore, none of the applicants addressed the space constraints and integration with the M5 East tunnel installation. All applications required excavation of additional space in the tunnel to house power, control systems and wash-water treatment equipment.
The assessment of the initial in-tunnel filtration concepts and the further consideration of the installation works necessary in the eastbound tunnel, determined that:
- Significant excavation and fit-out works would be required within the M5 East tunnel to provide space for power, control systems and wash-water treatment. To complete all the work, weeknight closures of the eastbound tunnel would be necessary, up to 5 nights per week for up to 8 months, which would cause unacceptable impacts on tunnel availability for traffic.
-
There was a lack of certainty in treating the required volume of air at the specified performance levels, and consequently there was significant uncertainty that the concepts could noticeably reduce the haze in the eastbound tunnel.
- Construction, installation and commissioning works were estimated at approximately $19 million (without contingency).
The assessment panel consisted of expert representatives from the RTA, and included an independent air filtration expert from the University of Sydney.
Conclusion
In conclusion, all the proposals would result in the closure of the tunnel - for significant periods of time. The RTA has an overriding objective to keep the arterial network – including the M5 tunnel – running efficiently and to minimise impacts on road users.
All the proposals were estimated to cost approximately $19 million or more to install. This and the inconvenience to drivers means the responses did not offer the community value for money.
The air filtration trial in the westbound M5 tunnel will start in March 2010, and operate for a period of 18 months. Information gathered about the performance of the equipment will be used in the consideration of any future tunnel air filtration arrangements.
M5 corridor 
