Attendees at the Linking Melbourne information sessions were told that the tunnel will reduce air pollution. This is an argument often used by the road lobby.

The argument is that by taking cars of congested roads and putting them in free flowing tunnels, there will be less pollution. Furthermore, the ventilation in the tunnel pushes the pollution up the vent stacks and away from the road, bringing further  benefits. Cars travelling at a constant 50km/hr do emit slightly less pollution that cars that are idling, and the mixture of pollutants is different. And vent stacks do push a lot of pollution higher into the ‘air shed’, where it has a better opportunity to be dumped somewhere else or dispersed. Also, car emissions are improving, as the fleet is renewed with stricter emission controls.

The problem with the first argument is that most of the cars will remain stuck in traffic jams. Many will be stuck in the tunnel trying to exit onto a clogged city road such as Hoddle Street. The tunnel will only add more cars and trucks to the mix. 

Some of the new traffic  will be queued up in a tunnel with an exit  just down the hill from the  Gold Street Primary School 1360 in Clifton Hill (1874, Victorian Heritage Register) Continue Reading…