Results mixed on MoPac lane changes

12 10 2011

(yet another file in the Saw this coming from miles away Department)

Ben Wear (Results mixed on MoPac lane changes): “At the same time, MoPac in that stretch went from two lanes northbound to three lanes. The idea, of course, was to improve the overall flow of the expressway with an extra lane (50 percent more capacity), even if that meant a little pain for some people trying to join the parade on one fewer lane (50 percent less capacity).”

Our Most Senior Fellow (just over a year ago; found in full here): “Welcome, dear audience, to the Braess Paradox, which ‘states that in a network in which all the moving entities rationally seek the most efficient route, adding extra capacity can actually reduce the network’s overall efficiency.’ This dynamic inverts as well. That is, reducing network capacity can actually improve the system’s effectiveness. Furthermore, Dietrich Braess also noted that ‘in a user-optimized network, when a new link is added, the change in equilibrium flows might result in a higher cost, implying that users were better off without that link.’

“With this restriping plan, among other issues drivers entering MoPac from 6th will have to merge into that new third lane – And as we all know how Austinites do nothing but embody the Braess Paradox when it comes to properly merging, especially onto an expressway. Thus, the bottleneck TxDOT is supposedly rectifying will be dispersed into several smaller bottlenecks in those areas where merging must occur.”

Wear: “Based on a follow-up study by the Texas Transportation Institute, the backup for the Cesar Chavez drivers in the afternoon has increased by an average of 1,500 feet. If we assume about 25 feet per car, counting the space between cars, that would be about 60 extra cars crawling for more than an extra quarter-mile…to sum up, to help South Austin folks get north much faster in the morning, and maybe a bit faster in the afternoon, downtown workers are getting a good long look at the lovely concrete back wall of Austin High School.”

Statesman reader Owen Pelligrin: “The solution isn’t to try and make more space for cars. The solution is better public transportation that goes from where people live to where people work. So long as people are encouraged to drive themselves everywhere, there will be traffic problems in Austin.”

And right now Our Most Senior sees fit to both quote Charles De Gaulle, who said “when I am right, I get angry,” and conclude with words by the incomparable Jonathan Swift: “When a true genius appears in the world, you may know him by this infallible sign: That all the dunces are in
confederacy against him.”

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2 responses

12 10 2011
Results mixed on MoPac lane changes « Sinclair Black's Urban Design Practice

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13 10 2011
Chris Bradford

The solution is to congestion price MoPac. Commuters will automatically adjust by (i) switching to public transit; (ii) commuting at different times; or (iii)ponying up the dough.

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