Figure 3: Monthly Variation in Weekday Congestion due to Seasonal Factors: Houston, Los Angeles, and Chicago

Figure 3: Monthly Variation in Weekday Congestion due to Seasonal Factors: Houston, Los Angeles, and Chicago

Difference in congested hours per day from the trendline

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  Houston Los Angeles Chicago
Jan –0.216294028 –0.012096943 –0.850994748
Feb –0.029454818 0.724020468 –0.231930471
Mar 0.186789726 0.860687182 0.039622471
Apr 0.21790421 –0.652242511 –0.384798326
May –0.129583329 –0.666660929 0.366345709
Jun –0.204731169 –0.202854984 0.525618652
Jul –0.303147959 0.130652301 0.237330595
Aug 0.041288585 –0.86127211 0.238419204
Sep 0.455383463 0.256234117 0.674736147
Oct 0.349822007 0.30091998 0.54646909
Nov 0.309430884 0.69264748 –0.129485633
Dec –0.677407572 –0.57003405 –1.031332691

NOTE: Each bar represents the degree of departure from the underlying long-term trendline. For example, the December seasonal factor for Chicago of approximately -1 means that, in December in Chicago, the number of congested hours per weekday is approximately 1 hour less than the overall trend for the weekday congestion.

SOURCE: Calculated from data used in preparation of Federal Highway Administration, Urban Congestion Report, April 2004-April 2007.