Transit operators say that one bus replaces 50 cars---making every bus strike a smack to the environment.
The actual impact is difficult to quantify. The only place in town counting cars is Halifax Harbour Bridges. Its spokesperson, Alison MacDonald, says they've seen spikes in peak-hour traffic since the Metro Transit strike began (excluding spring break week). Peak hours have also gotten longer (from three hours in the morning to four) as drivers try to beat the rush by commuting early or late.
On February 27, there were 29,426 vehicles during peak hours, a 7.6 percent increase over pre-strike traffic. At minimum, a couple thousand cars have replaced 300 Metro Transit buses. On February 13 there was a 3.3 percent increase over pre-strike traffic, which raises the interesting question: are we getting lazier about carpooling, more likely to drive, as the strike drags on? HHB has also observed, but doesn't count, an increase in the number of people walking and biking across the bridge.
Aside from limited data, comparing car emissions to bus emissions is made difficult by varying fuel sources (hybrid, gas or diesel), efficiency ratings, city versus highway driving, numbers of passengers and frequency of stops.
A report out of Duke University makes it all sound so tidy. "A typical passenger car carrying one person gets 25 passenger miles per gallon, while a conventional [diesel] bus at its capacity of 70 (seated and standing) gets 163 passenger miles per gallon."
That report has been criticized for using unrealistic assumptions of at-capacity buses and single occupancy vehicles. The reality in Canada is an average occupancy rate of about 1.6 persons per vehicle, and the occasional Link bus to Sackville that feels more like a stretch limo than public transit.
But, using what we do know, and making a few wildly entertaining guesses:
About 50,000 to 55,000 people take Metro Transit daily. I know, via Derek Gillis at Clean Nova Scotia, that the average return commute in HRM is 16 to 20 kilometres, and that a typical passenger vehicle emits 2.43 kilograms of greenhouse gases per litre.
Assuming an average fuel efficiency of 11 kilometres per litre (26 miles per gallon, mostly stop-and-go driving, keeping in mind the average car in Canada is nine years old), each day, each car is emitting about four kilograms of greenhouse gasses. If we assume, wildly, that almost half the people who usually bus each day have resorted to driving, that's an added 200,000 kilograms of emissions per day (conservatively), or nearly four million kilos since the strike began (as of March 5), on weekdays alone.
How does that compare to what the buses emit? Discounting the two hybrid vehicles (statistically insignificant), Metro Transit buses get a sad-sack 1.3 kilometres per litre, says Lori Patterson of Metro Transit. But there are only 300 of them, compared to 25,000 cars in my extremely rough but probably conservative estimate.
The buses travel 52,500 kilometres a day on that diesel, which emits 2.67 kilograms of greenhouse gas emissions per kilometre, for a total daily emission of 107,827 kilos---just over half of my conservative car scenario. It's an interesting, if bitter, taste of what the city will be like if development continues to favour sprawl and roads over sustainable transportation.
Surprise! Buses are better for the environment. Back to Derek Gillis, who provided some of these numbers. He's one of the people who responded to the Ecology Action Centre's callout to transit users and formed the new Transit Riders' Alliance.
"We figured it might be advantageous to have an independent third party informing both parties what users expect," he says. It's early stages yet and, besides weekly demos at bus stops, the group has mostly focused on gathering feedback, developing a platform and growing membership. Gillis says every action and meeting has grown larger as the strike lingers.
"We're looking at ways to reduce the numbers of single occupancy vehicles, like light rail and having free fare routes, and these kinds of alliances have been effective in Toronto, Vancouver and several American cities," Gillis says.
If the riders' alliance can catalyze a more effective transit system, at least something positive will have come from the strike.
Chris Benjamin is the author of Eco-Innovators: Sustainability in Atlantic Canada and the novel Drive-by Saviours.