Understanding traffic counts, also known as traffic volumes, is crucial for urban planning, transportation analysis, and infrastructure development. For the State Highway System in California, traffic count data is readily available in various formats. This data encompasses highways signed as Interstate, California State Route, or United States Route.
Alt: Interstate route shield sign, part of the traffic count information for California highways.
Alt: California State Route shield sign indicating state highway for traffic volume data.
Alt: US route shield sign, representing another type of highway with available traffic count data in California.
For a detailed explanation of traffic counts, including back and ahead leg diagrams, please refer to this document:
Explanation of Traffic Counts (Back & Ahead Leg Diagrams) (PDF)
Accessing Traffic Count Data for California State Highways
Traffic counts for California State Highways are summarized annually and categorized into four main types, all available in XLSX format for easy access and analysis:
Annual Average Daily Traffic (AADT)
This dataset provides the Annual Average Daily Traffic for all vehicles on California State Highways.
| Traffic Volumes: Annual Average Daily Traffic (AADT) For ALL vehicles on California State Highways All files are .XLSX |
|---|
| 2021 AADT |
| 2016 AADT |
| N/A |
Annual Average Daily Truck Traffic (AADTT)
For specific data on truck traffic, the Annual Average Daily Truck Traffic dataset is available, focusing on truck volumes on California State Highways.
| Truck Traffic: Annual Average Daily Truck Traffic For truck traffic on California State Highways All files are .XLSX |
|---|
| 2021 AADT Truck |
| 2016 AADT Truck |
| N/A |
Ramp Volumes
For those interested in traffic flow at freeway ramps, data is categorized by Caltrans District. Files from 2017-2022 are in XLSX format, while 2016 files are in PDF.
| Ramp Volumes For ramp volumes on California State Freeways, by Caltrans District 2020-2017 files are .XLSX and 2016 files are .PDF |
|---|
| District 1 |
| 2022 D1 |
| 2021 D1 |
| 2020 D1 |
| 2019 D1 |
| 2018 D1 |
| 2017 D1 |
| 2016 D1 |
| District 7 |
| 2022 D7 |
| 2021 D7 |
| 2020 D7 |
| 2019 D7 |
| 2018 D7 |
| 2017 D7 |
| 2016 D7 |
Peak Hour Volume Data
Explore hourly volume patterns and traffic monitoring site data on the State Highway System. Morning (AM) and evening (PM) peak periods are presented as a percentage of AADT.
| Peak Hour Volume Data Hourly volume relationships and traffic monitoring sites on the State Highway System. Morning (AM) and evening (PM) peak periods are expressed as a percentage of AADT All files are .XLSX |
|---|
| 2021 |
| 2016 |
| N/A |
Peak Hour Definitions K and D Factors (PDF)
Finding Traffic Counts on City and County Streets
For traffic count information regarding city and county streets, these data are managed at the local level. You can typically find this information by contacting the Traffic Engineering or Public Works Department, or the Community Development Office in the specific city or county where the street is located. These local departments are your best resource for street-level traffic count data.
For any questions related to the AADT reports, Ramp Volumes, or Peak Hour Volume Data Reports provided above, please contact Hasib Mohabbat.
Furthermore, for AADT GIS data, you can explore the Caltrans GIS Data webpage.
