Wednesday, July 8, 2009

TTI Congestion Lacking

Ok, I get it. TTI says we as a country are a congested place. But who's fault is that? It's certainly not mine. Riding BART almost every day I never see the congestion. But why? Because I chose to live somewhere I can avoid it. Many other people around the country make that choice as well. I realize some people don't. But where is the calculation of money saved on transit systems or cities that promote walkable and bikeable neighborhoods that operate efficiently and allow people to leave for work at the same time every day for 20 years and never see a change. We know the congestion issue is a big one because most people drive. But should we be talking about congestion in terms of cars alone? Perhaps in cities that don't have transit. But is it a bit disingenuous to say that the Bay Area is one of the most congested when in parts it isn't, or people have ways to avoid it if they so choose? I think it might be.


Anonymous said...

Though then we have the O'Toole & Cox types that would say you are preventing them from putting down more asphalt.

rg said...

I make the same silly joke each time TTI releases its congestion report, feigning surprise and shock at learning "DC" suffers from the nation's xth-worst congestion; the point being that while perhaps the DC region suffers from bad congestion, as someone who lives and works in the city and does not drive, I never really experience this congestion. I generally find it really easy to get around and to where I want to go. Indeed, once all fo the suburbanites have gone home, it is amazing how little traffic there is in DC proper in the evening and on weekends.

Cavan said...

I was about to say exactly what rg said. The only difference is that I live in an walkalbe urban suburban town in Montgomery County, MD. I walk to the Metro every day and only use my car once a week if I have to go out into sprawl and that's never during rush hour. No congestion for me!

The study includes data from super car-dependent places like Fairfax County, Loudoun County, and Prince William Counties, Virginia. Those places had no planning, very wide suburban arterials, little transit, and no walkable urban places where transit would work.

Daniel M. Laenker said...

I was going to follow up with exactly what the other commenters have said; to the same extent, just because there are very walkable parts of the Bay Area doesn't mean that in the aggregate there isn't a great deal of traffic congestion.

So, um, no, it isn't unfair. It's much in the same way that it's not unfair to say that greater New York, in the aggregate, is less congested.

Michael said...

To be fair, they do talk specifically about traffic congestion.

Your point is a good one, though. A better measure than traffic congestion would quantify how easy it is for people to get to where they need to go, with the modes of transportation available to them.

Winston said...

The TTI's methodology stinks for several reasons. Essentially what they do is look at a metro area's annual VMT and divide it by the number of lane-miles of freeway and arterial roads and a fudge factor based on how much public transit the city operates. The result of this is that cities with well designed road networks that invest in congestion management techniques (such as ramp metering) are penalized. Meanwhile cities with less well designed road networks or that run lots of transit rank better than they otherwise would (see Atlanta or NYC).

A much better measure of congestion is the Census Journey to Work data which is tabulated every 10 years.

Here is a document that contains a cool map of the U.S. that shows how long people actually spend commuting by county. The data is available by census tract if you want to poke around on the Census website.

Anonymous said...

In 2001, the Surface Transportation Policy Project (STPP) put out a companion study to the TTI report called "Easing the Burden" ( It basically ranked cities based not just on how much auto congestion there was, but on the degree to which a given urban area is burdened by that congestion - that is, is it possible to avoid the congestion by not driving and instead taking transit, walking, biking, etc.

By this measure, the Washington, DC area is far less "burdened" by congestion than the TTI numbers suggest, because such a large proportion of people in the region aren't driving cars to work. Congestion on the roads still sucks for drivers, but it's relatively easy to avoid it given the well-established bus and rail systems.

By contrast, an urban area like Detroit moves up toward the top of the "burden" rankings - even though it has far less auto congestion than DC, virtually everyone there must suffer through it as there's no viable alternative for getting around that city.

John said...

"But where is the calculation of money saved on transit systems or cities that promote walkable and bikeable neighborhoods that operate efficiently and allow people to leave for work at the same time every day for 20 years and never see a change."

There is a line in the detailed reports for each region that shows the "Congestion Cost...if Public Transportation Service were Discontinued." The value for SF is shown as $658.9 Million. See report page 9 of 10.

I'm guessing that you're looking for more details.