If you care about embodied carbon, money or time, you don't dig. But then this is Toronto.
In the former Toronto suburb of Etobicoke, Eglinton Avenue West is a fast-moving arterial road that would be perfect for surface transit. But in 2012 the late mayor Rob Ford rejected this:
Now his brother is running the province of Ontario, and actually has the power to demand this. And as Alex Bozicovic notes in the Globe and Mail, there is a huge price to pay in time, in money and in the carbon footprint.
People want subways, folks. They want subways, subways. They don’t want these damned streetcars blocking up our city. That’s what they don’t want….I’m not going to support the LRTs, I’ll tell you that right now. I’m going to do everything in my power to try to stop it.
Underground tunnelling “takes much longer, and it uses much more construction material, which has a massive environmental impact,” said Shoshanna Saxe, an assistant professor at the University of Toronto’s school of engineering. Prof. Saxe and two colleagues recently wrote a paper on the subject and found that underground rail generates 27 times more greenhouse gases than surface rail.
We have quoted Saxe and her study before about this in Big transit projects have a big carbon footprint. But more recently, we have been asking What happens when you plan or design with Upfront Carbon Emissions in mind? We are in a world where every tonne of carbon dioxide has to be measured against the budget we have if we are going to have a chance of keeping the temperature rise under 1.5 degrees. In such a world, "you don't bury things in concrete tubes when you can run them on the surface." But as Gil Penalosa reminds us, Doug Ford isn't thinking about transit or urban design; he is thinking about people in cars.
Overwhelming majority of people who ‘demand underground subway’ have NO intention on using it. Their hope is everyone else will, and they will have empty streets for their cars! Limit car space and allow SAFE enjoyable walk, bike, transit at level w view of sun, people, trees...— G_Penalosa (@Penalosa_G) March 31, 2019
It should be about city building, not city emptying.
Asher, a Twitter buddy, quotes Terence Bendixson: "[Subway] tunnels are people-sewers into which people are flushed as if they were some kind of urban contagion that must be banished from the townscape with utmost haste." And we wrote in an earlier post on this subject:
As urban cycling and planning advocate Mikael Colville-Andersen notes, "We don't advocate shoving citizens underground. We want them on street level on foot, on bicycle and in trams." Because when people are underground they don't see what is going on around them, what is happening at grade, what new store or restaurant opened because there was now transit that could bring customers.
Bozicovic concludes with a quote from Saxe: “In a world where we’re serious about our climate crisis, we need to built infrastructure that’s fit for purpose, and be cautious with our resources both financial and environmental.”
Perhaps it is time for Justin Trudeau to put a big honking carbon tax on concrete to help ensure that we make smart choices about how we use the stuff.