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100 busiest roads in California

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The list show road sections, all freeways have a certain AADT between two exits, and that's what listed above.

J N Winkler:
That is not quite the case.  The list shows AADTs at the postmiles where traffic counters are located.  There are a few runs of consecutive listings for the same freeway where a given level of high traffic volume on that freeway straddles several counter locations, but these are not listed in postmile order since the sort is by highest traffic volume.  As an example, a length of I-110 (Harbor Freeway) has AADTs ranging from 332,000 to 335,000, but the exits are listed as Gage-Florence-Manchester-Slauson when on the ground they are Manchester-Florence-Gage-Slauson (going northbound).

The listing is highly susceptible to counter density.  For instance, a lot of counters in locations which have high traffic volume (which you could expect to be the case since counter data is needed for active traffic management and for assessing the success or otherwise of minor capacity improvements, which are pretty much all that can be done in very busy corridors) will squeeze out busy locations further down the list.

One way to remove counter location and density as protential confounders would be to compile a list of the 100 busiest corridors in California.  For purposes of such a list, a corridor of high traffic volume would have to be centered on the location of peak counter AADT and extend to the points (on either side of the peak) where the AADT drops by a set percentage (perhaps 10% or 20%).

I don't think the Caltrans list has ATR locations only, but for all road segments (as in: between two exits). Counters are usually not installed between every exit, but between a couple of exits, and they estimate the other locations, at least that's how it's done in Europe.

This list I got from Caltrans has every road segment between two exits.

Chris is correct -- Caltrans doesn't count every location, and does estimate both total volume and truck volumes between count locations.

For freeways, Caltrans reports volumes between all interchanges.  For non-freeways, it reports volumes more sporadically.


--- Quote from: mapman ---For non-freeways, it reports volumes more sporadically.
--- End quote ---

I think between major intersections, not between every country road that leads to nowhere.


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