Highway networks are often compared to the human circulatory system, an analogy that works on many levels. The hierarchical structure of highways, streets, and local roads matches that of our body’s arteries, veins, arterioles, venules, and capillaries. And like the circulatory system, highways serve as the infrastructure by which resources are distributed to where they are needed, keeping the system healthy and helping it to grow.
The analogy also works visually, as demonstrated by the map below. What’s shown is the U.S. Interstate Highway System. The width of each section represents the average traffic for each hour of the day. Use the slider bar to select a time of day or press play to watch the traffic fluctuate over 24 hours (the time shown at the top is Eastern Standard Time).
To navigate around the map with a mouse:
- Rotate: left mouse button + drag
- Pan: right mouse button + drag
- Zoom: middle mouse button (or both buttons at the same time) + drag
Hourly Traffic on the US Interstate, Visualized as a Living Circulatory System (full screen version)
This map builds on a similar one I made a few months ago, an image map showing the average daily traffic volume across U.S. highways. Thanks to reddit user cdsvoboda for the suggestion to make an animated version.
The information is submitted to the DOT by each state on a monthly basis. It includes hourly traffic counts for each hour of each day of the month at approximately 4,000 continuous traffic counting locations nationwide. The traffic counts are also broken down by road lane and direction of traffic, which, for the one month of data used here, amounts to a total of 14 million traffic count readings and a total of 6 billion vehicles counted.
The map includes only the U.S. Interstate. So unlike local traffic, which exhibits two daily “heart beats,” morning and evening rush hour, this map follows a 24 hour cycle with only one peak. On the Interstate, traffic bottoms out at 2am and steadily climbs until reaching its highest point at 4pm.
- Data for the map was acquired through a Freedom of Information request with the DOT (downloadable here). If you’d like to learn more about the Freedom of Information Act, you can find more information on my website FOIA Mapper. For another interesting DOT dataset dealing with U.S. road traffic, see FARS, the data behind this map of U.S. traffic accidents.
- Update: Originally, the map showed each time zone in its local time (e.g. 9am in New York appeared at the same time as 9am in L.A.). The map has since been updated to show the traffic without regard for time zones (e.g. 9am in New York appears at the same time as 6am in L.A.). The hour shown at the top is Eastern Standard Time.
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