This type of hard data seems imminently more valuable than the modeling that has traditionally tried to define congestion, such as the work by the Texas Transportation Institute (TTI), and it is little surprise that TTI’s ranking of the most congested areas differs from INRIX’s. INRIX ranks the top five congested areas as Los Angeles, New York, Chicago, Washington DC, and Dallas. TTI ranks them (based on 2005 data) as Los Angeles, San Francisco, Washington DC, Atlanta, and Dallas. TTI bases its estimates primarily on survey data of travel habits and broad statistics such as traffic volumes and highway lane-miles. The flaws in this type of methodology have long been apparant, but no better alternatives existed. It will be interesting to see how INRIX's data is harnessed gonig forward to overturn other pieces of flawed conventional wisdom. Comments on this thought are encouraged.
In addition to better defining the congestion problem, INRIX’s data enables the pinpointing of specific trouble spots such as interchanges, construction zones, and merge lanes. The value of such cutting edge analysis is that it allows metro areas to identify and fix the flaws in their transportation systems. Experts and planners in the transportation community have long called for better data to help them understand and predict how transportation networks function, and that call is finally being answered by the sophisticated technologies of companies like INRIX. With more real data becoming available each day, let’s hope that real improvements in mobility soon follow.
-Daniel Lewis
1 comment:
Keep in mind that one of the main reasons why the rankings are different is due to how TTI treats transit. The actual computations are complex, but, basically, under TTI, a transit rider on a bus or train running on schedule during peak is counted as as "1.00" trip (no congestion) -- even if the transit trip takes longer than driving during peak.
The extreme is NYC, which has such high transit use. Even though the average home-to-work commute trip time is far higher in greater NYC than greater LA (Census Bureau), because the NYC transit travel percentage is so much higher, NYC's TTI score is far lower.
Tom Rubin
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