Finding Traffic Volume on Washtenaw County Roads

Washtenaw County belongs to the Southeast Michigan Council of Governments aka “SEMCOG”. The SEMCOG website has a bunch of great data, maps and information concerning transportation related topics throughout out county. I am going to be briefly discuss how you can find traffic volume data for the county on SEMCOG’s website.

SEMCOG Traffic Volume site reports traffic count information for all reporting agencies and municipalities within the region. Although these different entities individually report their traffic counts, the SEMCOG site is a good place to start looking at this because it shows all reported traffic counts  in one location regardless of road ownership and also shows the year the count information was taken.

The SEMCOG Traffic Volume map can be found at

Below is a screen shot from SEMCOG’s site showing part of the county:


Zooming in on US-23 just north of Geddes we can click on the road and get the SEMCOG traffic count information:


So the Average Annual Daily Traffic (AADT) for two lanes (one way) of US-23 in 2009 was 37,500 (according to SEMCOG). We also learn that the State (MDOT) has jurisdiction over the road.

Since this data is 7 years old, this is a great jumping off point for us to see if MDOT has more recent traffic counts for this road. Going to MDOT’s Traffic Volume Map and zooming in on the same stretch of road we see that their 2015 2-Way AADT count is 67,700. This 2-way count is less than double the one-way count reported by SEMCOG in 2009 which is not something we would expect. Traffic generally increases on a year to year basis.  Going back a year to 2014, the AADT count for the same stretch of road was 81,700 which would be more in line with a general increase from the 2009 reported SEMCOG value to today (75,000 two-way to 81,700).


There is a lot more to be said about traffic volume, counts, and traffic in general in our fair county but this is a just a brief introduction into how to actually find this traffic count information through the SEMCOG mapping portal – hopefully we can look at this data in more detail in the future and also the data as reported by individual agencies and municipalities.


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