The road tunnel emission time bomb

WestConnex exhaust stack at Arncliffe. Photo: Andrew Chuter

There are two approaches to ventilating road tunnels — filtering in situ or diluting the toxic emissions into surrounding areas. The New South Wales government has opted for the latter, claiming it is world’s “best practice”.

The best method is “in-tunnel filtration”. The tunnel design includes special areas adjacent to and at staggered points along the length of the tunnel to house the filtration equipment which removes particulate matter and the oxides of nitrogen.

Tests in Japan and other countries have proven that releasing the scrubbed, clean air back into the tunnel is almost 100% effective.

By contrast, NSW has opted for a sub-standard, absurdly expensive and totally ineffective approach. It imports the exhaust emissions, pushing them along the length of the tunnel and then attempts to dilute it by sucking in air from outside and finally pumping the polluted mass out via exhaust stacks which are not fitted with any filter.

With this system, the closer a vehicle gets to the exit portal, the greater the volume of air and exhaust pollution in the tunnel.

With four exhaust stacks in close proximity, Rozelle can be described as Sydney’s exhaust pipe.

For residents who live in the fall-out zones and to those people sitting in the slow moving and stalled tunnel traffic this is significant.

Despite the level of cancer-causing polluted air adjacent to the portals being so high, Australia’s approach is to dilute and release the unfiltered tunnel air. The powers that be continue to lie about the approach being “world’s best practice”.

Pumping high concentrations of cancer-causing pollution from the exhaust stacks is no solution. It is a problem.

Although particulate matter and oxides of nitrogen can be almost entirely eliminated through tunnel filtration, there is no viable filtration technology for carbon dioxide (CO2), the primary component of car exhaust.

Carbon dioxide’s contribution to the global climate emergency is well-known. Upgrading public and active transport infrastructure can help address this problem.

However, the multi-billion WestConnex tollway system was not designed for this.

Retrofitting 33-kilometres of WestConnex tunnels to filter the air is possible, but highly improbable.

Apart from who would have to pay for it, the government and the Roads and Maritime Services would be forced to admit they got it wrong — from the design phase.

If they were forced to admit they had lied and continue to lie about “world’s best practice” air filtration and that the diesel exhaust plumes they would then be faced with problem of retrofitting every road tunnel in NSW.

This could lead to other states and territories doing the same.

Obviously the authorities would leave themselves open to huge compensation claims of wrongful death, just like cigarette companies. But, just like the cigarette companies, proving causality is the stumbling block.

The fact that both major parties support the WestConnex shouldn’t stop us from demanding that the tunnels be filtered.

It will be years before fossil fuel burning vehicles are outnumbered by vehicles powered by green technology.

In the interim, hundreds of thousands of locals will die prematurely because of the unfiltered exhaust plumes, dumping hundreds of tonnes of carcinogenic material annually into the air that you, I and every other local person and tunnel user is forced to breathe.

The plume, generated by just 2.2 kilometres of tunnel, demonstrate that.

After alarm bells rang, tests were done to determine the cause of the cancer cluster in Turrella residents, who lived downwind of the exhaust stack plume. The group showed a 44% increase in lung cancers while over the same period, the state average fell by 9%.

The Cancer Council states that is the second most common cancer-causing agent, but Labor and Coalition governments refuse to take this on board.