How fast is your bus, really? New state data reveals California's transit speed divide

A sweeping new dataset from Caltrans lays bare what millions of California commuters already know: the speed of your bus depends enormously on where you live, which agency runs your route, and what time of day you're riding.

The data—published on California's Open Data Portal—tracks average transit speeds segment by segment, stop by stop, across every California operator that provides real-time vehicle position data. With more than 573,000 records covering peak and off-peak periods, it's one of the most granular looks at transit performance ever assembled for the state.

Explore the Data

The interactive tool below draws directly from the Caltrans live dataset. Filter by Caltrans district, transit agency, and time period to explore speeds in your region. Segments are color-coded by median speed—red for the slowest, green for the fastest. The P20 and P80 columns show the slow and fast ends of the range, giving you a sense of how consistent (or chaotic) each segment's performance really is.

What the Data Measures

For each segment between two stops, the dataset records three speed thresholds: the 20th percentile (the slowest typical trips), the 50th percentile (the median), and the 80th percentile (the fastest typical trips). It also distinguishes between AM Peak, Early morning, midday, and other time periods—allowing a direct comparison of how much traffic degrades transit performance throughout the day.

The gap between the 20th and 80th percentile tells its own story. A route where the slow end is 8 mph and the fast end is 22 mph is a route plagued by unpredictability—riders never know if their trip will take 20 minutes or nearly an hour. Consistency, transit planners argue, matters almost as much as raw speed.

Peak vs. Off-Peak: How Much Does Traffic Actually Slow Your Bus?

Across the dataset, AM Peak time periods consistently show lower median speeds than early morning or late evening runs—in many cases by 30 to 50 percent. That gap represents not just lost time for individual riders, but a structural disincentive to use transit for the commute trips it was designed to serve.

Freeway-running routes show the most resilience—when buses have dedicated right-of-way, speeds hold up even during peak hours. Surface-street routes in dense urban cores tell a different story, with many segments recording median speeds in the single digits during morning rush: slower, in some cases, than a bicycle.

Transit advocates have long argued that bus-only lanes and signal priority are the most cost-effective tools for closing the peak/off-peak gap. The Caltrans data now provides the evidence base to identify exactly which corridors would benefit most—and which agencies are already outperforming their peers.

Data: Caltrans Average Transit Speeds by Stop, California Open Data Portal. The dataset covers all California transit operators providing GTFS real-time vehicle positions data. Speeds are estimated from a single representative day per operator.