Skip Navigation LinksDOT > Projects & Programs > Planning > Traffic Information

Traffic Information

In its mission to maintain Pennsylvania's transportation system, PennDOT monitors traffic information, provides traffic and Geographic Information Systems resources for partners and stakeholders, and much more. The department also facilitates safe traffic counting across the state.


Highway Statistics

National Highway System (NHS)


Functional Classifications


Traffic Data


Frequently Asked Questions

What are traffic counts used for?
Traffic information is critical in transportation decision making related to highway funding, traffic engineering, highway design, planning, programming, and air quality analysis.
When is traffic count data collected?
PennDOT has an established program for collecting traffic data. Traffic data is collected at approximately 30,000 sites statewide. The sites are on various collection cycles: annually, every three or five years, depending on priority of the highway system. 10,000 traffic counts are taken each year at selected locations.
What do the red numbers on the Traffic Volume Maps mean? What about the black ones?
The red numbers are the State Route numbers. You may also obtain more information on the legend located on the map. The black numbers represent Annual Average Daily Traffic (AADT). AADT is the typical daily traffic on a road segment for all the days in a week, over a one-year period. You may also obtain more information on the legend located on the map.  
Why aren't there any numbers displayed on the map when I enlarge an area?
You are probably within an enlargement on the main body of the map; the enlargement areas are shaded and identified with an enlargement number. The enlargement areas are displayed off to the side of the main body of the map.