A brilliant series of articles on transportation in the current Vancouver Magazine here, here and here

The most important piece is by Charles Montgomery, who travels along with Lon Laclaire, the City’s Strategic Transportation Manager, and learns some lessons.  Like this one:

In 1968, the German mathematician, Dietrich Braess, was modelling the response of traffic to different road networks. Braess assumed that drivers keep adjusting their trips until they find the quickest commute possible. This is one of the premises of EMME/2, the computer program used to predict traffic flows in every big city around the world. The EMME/2 models assume that, like water molecules in braided streams, cars will distribute themselves until all roads are pretty much flowing equally. This is why the Alex Fraser Bridge was jammed within a few months of opening. It’s also why your shortcut to work never stays a shortcut for long.

Braess discovered a curious wrinkle in the traffic universe. His math showed that adding new capacity to an existing network of roads can actually lengthen peoples’ commute time. This fact is fueled by human selfishness: We all try to choose the fastest route home. But when ten thousand of us make that same choice in isolation, we all just might arrive home later.

LaClaire heard about Braess’ Paradox from a visiting traffic scholar in a Wall Centre conference room back in 2000. He remembers the equation, and the epiphany it brought. His blue eyes twinkle as he recalls the moment he raised his hand.
“I said, ‘Hey, maybe these paradoxes, these problem roads, already exist in our city. If they did, we’d just need to take them out to improve the flow!’ I thought it was a brilliant idea. I mean, these problem roads must be out there.”
In the engineering world, it has long been heresy to suggest that less concrete and asphalt might be preferable to more. LaClaire had crossed the line. “The guy looked at me like I was a freak. He laughed, like I was joking, and then he just went on teaching.”
LaClaire furrows his brow as we cruise through another amber. “But I was right.”

Comments

  1. Those are a great series of articles. However I found a pretty glaring typo in the Bus article. It states on page three that “The annual BC Hydro bill for trolleys is about $1.8 billion, or about 16 cents/km per bus.” The $1.8 billion figure cannot be correct.
    Earlier the article states an average diesel bus travels about 70,000km/yr and there are about 250 trolley buses. For the sake of argument lets use the diesel mileage figures and the 16 cents/km per bus energy cost. That only works out to yearly hydro bill of $2.8 million for the trolley fleet and that assumes the trolley buses accrue as an equal number of kilometres as the diesel variants. Bottom line, I would hazard to guess the “b” in billion should have been an “m” in million.

  2. One comment is that the model mentioned assumes that a proper arterial road network is in place – which is fine for Vancouver, with its grid system, but in the suburbs, that’s a different story because the arterial road system isn’t nearly as complete when it needs to cross rivers.
    A driver travelling from Kerrisdale to Commercial Drive has a lot of potential routes. Ditto for Kits to Oakridge, etc. But when you have the bottlenecks imposed by bridges the formula/model must change.
    For Vancouver, Burrard, Granville, Cambie and Main (formerly a trestle, now on landfill) all provide convenient arterial bridge connections and extensions of the City’s grid into the downtown core. That level of arterial network connectivity and route options does not exist over the Fraser River (whether Coquitlam/New West – Surrey or Vancouver – Richmond) or over Burrard Inlet.
    By comparison, imagine that the current Canada Line trench down Cambie Street is the Fraser River, think about the impact on east-west connectiveity across the City of Vancouver that has occurred – and then remove a few crossings over the trench. That’s what a short distance traveller crossing a river has to face without a proper arterial network.

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