There they go again. First, the Texas Transportation Institute came out with its urban congestion rankings. Then it was traffic firm INRIX’s turn. Now, TomTom, which makes in-car navigation systems, has its own urban congestion rankings. And as the Seattle Times pointed out yesterday, TomTom’s methods rank Seattle as having the continent’s fourth-worst congestion. Meanwhile, Vancouver, BC, ranks #2 on the continent, second only to LA.
But TomTom’s methods have the exact same flaw that economist Joe Cortright has pointed out in the other reports: their measure of congestion looks only at car speeds, not at total travel time for people. In fact, compact cities with short commutes can actually get penalized in these rankings!
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To explain how TomTom’s ranking can penalize cities with short commutes, let’s imagine two metropolises: Compact City, where car commuters don’t have to travel too far during their daily commute; and Sprawlville, which is more spread out. In Compact City, congestion boosts the average commute from 20 minutes to 25 minutes—a five minute delay, adding up to a 25 percent congestion “penalty”. In Sprawlville, a typical 30 minute commute is lengthened to 35 minutes by congestion—also a five minute delay, but a congestion penalty of only 17 percent.
Both cities have the exact same congestion delay, and residents of Compact City actually spend less time behind the wheel during rush hour. Even so, TomTom’s methods (just like those of INRIX and TTI) would rank Sprawlville as having far less “congestion” than Compact City.
TomTom’s congestion index also leaves out the experiences of people who walk, bike, or take transit. In Seattle that’s over 30 percent of commuters, in Portland 22 percent and Vancouver (BC) 42 percent. Some of these commuters are affected by congestion, but some aren’t—and regardless, they’re effectively invisible in TomTom’s rankings.
All of this is to say that comparing cities’ “congestion rankings” can obscure more than it reveals. No matter how sophisticated the data that is used to generate them, the methods remain flawed—and at least somewhat divorced from people’s actual experience getting around town.
Yeah, well, ok, maybe the methods ARE questionable. But, as a later version of the Seattle Times article points out, “[w]hether we’re fourth or only seventh, what the numbers say is that frustrated travelers here aren’t delusional. Seattle endures volatile traffic and more congestion than most of its peers.” THAT is unquestionably true!
But what I’m wondering is, why does the study say that WEDNESDAY MORNINGS are one of the “worst times to travel”? (Friday afternoons are the other “worst time,” and I think I can figure THAT out!) But what’s up with Wednesday mornings? Top Pot Doughnuts got special deals, or something?
My theory about Wednesday is that the fewest people take that day as vacation. When you take vacation you tend to take Thursday and Friday or Monday and Tuesday.
My theory — just a theory — is that folks who work part time and/or 4×10 workweeks tend to take off on Monday or Friday. So there may just plain be more commuters on Tue-Fri — and perhaps Wednesday is simply the peak day for the # of commuters.
Hmmm…thanks, Andrew and Clark – very interesting theories.
I wonder if the Wednesday morning peak is UNIQUE to the Seattle area? And if so, why? …Maybe with Seattle being a “convention hub,” most businesses in the PNW region hold their conventions / conferences / meetings on Wednesday mornings during the first quarter of the year?
…And then on Friday afternoons there’s a mass exodus from the weekly conventions that started on Wednesday mornings…
myna lee johnstone
During the Olympic in Vancouver people used park and ride
They can do it everyday if they had the will to become the best city and area in Canada
There are few acceptable excuses to use the car,van,SUV,etc6
Three organizations have decided that what people want to know about urban traffic congestion is how slow and crowded the roads are. Seems reasonable to me.
That information helps people decide where they want to live, both in the large sense of choosing one region over another, and in the smaller sense of how close they want to live to their employment, shopping, and best friends, and whether they want to be well positioned vis a vis available public transit.
Comparing average regional travel times is an interesting add-on analytical exercise, but that doesn’t mean that the work of TTI, INRIX, and Tom Tom is flawed. Seeing what’s happening with vehicle movement on the roads both over recent history and in real time (because of the anonymous cell phone location readings used by these organizations and fed into various online services and electronic highway signs) is a wonderful thing for travelers making decisions.
One anecdote — I’ve been in a position in the past to use my traffic monitoring smartphone to advise the driver of an inter-city commercial bus about the extent of the traffic congestion ahead, in one case motivating the driver to make a route diversion to avoid a snarl, and in another case leaving us all not worrying because the road became clear just a little further ahead.
Except these three congestion indexes aren’t measures of absolute travel time or even absolute speed, nor do they take into account distance traveled. If I offered you a new place to live and told you nothing about how long it would take to get to work but merely that you would experience “no congestion” would you take it? Or would you perhaps be a bit curious as to whether you would spend 4 hours a day in your car? As we pointed out above, a higher “percent” congestion doesn’t necessarily mean shorter travel time and visa versa. A good congestion index score is not a guarantee of a short commute!
Also, you appear to be conflating real time traffic information with congestion indexes. These are completely different things, one focuses on actual travel times on specific routes and makes no attempt to generalize or rank while the other attempts to compare cities with vastly different physical makeups.
A Victoria community newspaper, Diversity Reporter, published Vancouver congestion story recently, but story photo that includes a couple of three-wheeler scooter-taxis doesn’t reflect Vancouver congestion but rather the traffic congestion in Mumbai: http://goo.gl/2bfSr
On the positive hand, such ‘bad news’ tends to keep people from moving here, even if it also motivates advocates for road expansion.