There's so much about WestConnex, the proposed 33-kilometre toll road across and under Sydney, that doesn't add up in so many ways, but nothing as much as the NSW government's claims about its climate change benefits.
The Baird government claims this $15.4 billion road across the inner west and south-west will be good for the climate.
WestConnex is a looming megaproject that almost seems to have evolved from another era in public life, a period when a Prime Minister believed coal was good for humanity, his top business adviser thought climate change was a United Nations plot, and Clive Palmer was a political force to be reckoned with.
WestConnex today is a project whose time has come and gone before its design has even been finalised. From the PM down, most recognise the need to deal with climate change.
For three years, the NSW government, proponents of WestConnex, said nothing about the toll road's climate change impact. But last month the environmental impact statement for the M4 East extension – public submissions for which close next Monday – included analysis on greenhouse gas emissions from consultants Aecom, the same firm that announced last month that it would no longer provide traffic and revenue forecasts for toll road operators, having settled a $280 million legal case for overly-optimistic forecasts for a proposed Brisbane toll road.
The M4 East section comprises two three-lane tunnels and linking roads and interchanges from Homebush to Haberfield; the environmental impact statement steps us through forecasts for greenhouse emissions from vehicle exhaust. The conclusions do not add up.
Aecom calculated the "vehicle kilometres travelled" (one vehicle travelling one kilometre, or the "VKT") in one year along different sections of the M4 East, including the tunnel, and the alternative route on Parramatta Rd. By 2031, on their figures, there will be 41 per cent more light vehicle traffic (cars, vans and motorbikes), from 266 million to 375 million VKT, if WestConnex is built compared with if it was not built.
For heavy vehicles (trucks and buses) it is forecast to double annual VKT from 27 million to almost 57 million by 2031 with WestConnex compared with if it wasn't built.
Elsewhere in the document these increases are explained as being because of the "attractiveness" of WestConnex for trips to the city, airport and Port Botany. That is, new roads induce more traffic.
Calculations are then made about vehicle types, their fuel consumption and their speed to conclude there will actually be a decrease in overall fuel use. Light-vehicle VKT may be up 41 per cent but total fuel consumption falls 11 per cent. Trucks movements double but their fuel use is down 13 per cent.
This lower fuel use, thanks to WestConnex, is why this environment impact statement suggests vehicle greenhouse emissions will be lower with WestConnex than without.
How can this be? We read: "As improvements to traffic flow and congestion are achieved through increased speeds, reduced travel distances and reduced frequency of stopping, fuel efficiency is improved and subsequently GHG [greenhouse gas] emissions associated with road use are reduced."
We're told that because traffic will be whizzing along rather than stuck in a jam, less fuel will be used. This argument has for years been discredited: what matters is the VKT. Higher VKT means higher greenhouse emissions. No credible authority in the world today would suggest that building freeways is the solution to cutting national greenhouse emissions.
And in fact, by 2031 WestConnex traffic will not be whizzing along. The official analysis shows that by 2031 there will be "high traffic densities" in the M4 East tunnel "particularly westbound during the AM peak where capacity is reached". In other words, the tunnel will be chockers and at a standstill.
What then? Build another six-lane tunnel?
Gavin Gilchrist is a sustainability consultant. He worked briefly this year for NSW Greens MP Jenny Leong.