Assessment Process Documentation

In summer 2020, the Caltrans Division of Rail and Mass Transportation (DRMT) published the California Minimum GTFS Guidelines to help transit providers understand the quality of their transit data.

Since then, DRMT has been sending transit providers assessments of how well they are meeting these guidelines, along with optional resources to help them reach compliance. We are now formalizing these efforts, working with providers to help them understand how to respond to these assessments.

What are the Guidelines?

The purpose of the California Minimum GTFS Guidelines is to set expectations surrounding data quality for transit providers so they can:

  1. Provide the public with complete and accurate information – including standardized schedule, service, fare, pathway, and geographic data—so riders can easily and seamlessly plan journeys regardless of their familiarity with a system or accessibility concerns
  2. Provide riders with real-time information so they can make informed decisions along their journey using reliable information about vehicle arrival times
  3. Make information easy to use in any application by providing standardized and publicly discoverable static and real-time GTFS data feeds
  4. Pursue industry standardization in order to provide better coordination, service delivery, and clear information for the industry in the future

DRMT published Version 1.0 of the California GTFS Minimum Guidelines in September 2020 following three months of feedback on draft guidelines. This version of the Guidelines includes an aspirational ten-point checklist to achieve the above four goals within the context of current data standards and products. This checklist includes practices such as:

  • Publishing GTFS Schedule and standard GTFS Realtime (GTFS-RT) formats at stable fetch URLs
  • Properly implementing the GTFS specification according to industry best practices
  • Keeping GTFS Schedule relatively up-to-date and consistent with other schedule sources
  • Maintaining high uptime and update frequency for GTFS-RT
  • Making this data available to consuming applications through common feed aggregators with simple open data licenses and providing technical points of contact

In order to serve as the most up-to-date reference of what we expect from transit providers, these Guidelines will evolve as we learn more about transit provider processes and as the GTFS standard continues to evolve. Each spring, Caltrans will review feedback and update the Guidelines. For example, the GTFS Grading Scheme A3c (Google Docs) was not adopted when Version 1.0 of the Guidelines was formalized, but it will likely be included in a subsequent version.

The full list of Guidelines, as well as high-level guidance on how to meet them, is available on Caltrans' website.

GTFS Transit Data Assessments

In 2021, a Caltrans Transit Data Assessment team will review each transit provider on behalf of DRMT. Assessments will identify any gaps between the most recent version of the California Minimum GTFS Guidelines and the provider's current schedule information.

Most of the guidelines refer to straightforward and simple conditions that the provider should be able to confirm independently. The second guideline ("implement all recommendations made in the GTFS Best Practices"), requires a closer, more thorough examination of data quality and the use of custom validation tools. All three of these tools are available to the public under open licenses, but they are difficult to use. So the Transit Data Assessment Team is available to collect and interpret feedback from the tools until they are improved. The tools answer the following questions:

  • How well does a static GTFS feed implement the GTFS specification? Are all the required GTFS Schedule fields present? To answer these questions, Cal-ITP uses MobilityData’s GTFS validator.
  • How well does a GTFS-RT feed implement the GTFS specification? Are trip IDs used consistently between static and real-time feeds? Are all the required GTFS-RT fields being used correctly? The Transit Data Assessment team uses the University of Central Florida’s GTFS-RT validator to look for these issues.
  • How well does the schedule described by a GTFS feed match other rider information sources? Does the route name in my trip planning application (which is informed by GTFS) match the variable display on the bus? MobilityData developed a GTFS Grading Scheme A3c1 (Google Docs) that samples route names, stop locations, and more to compare GTFS and other information sources.

What is a Transit Data Improvement Strategy?

If transit providers would like support in resolving these identified gaps, DRMT can provide technical assistance to create a Transit Data Improvement Strategy. Transit Data Improvement Strategies will

  1. Have a three-year planning horizon with clear annual milestones
  2. Articulate how the transit provider will meet the California Minimum GTFS Guidelines, naming any specific hurdles
  3. Define what resources Caltrans will provide to help the provider overcome these specified hurdles
  4. Be updated in 2022 while Caltrans evaluates next steps

In recognition of the current state of transit data demonstrated in the Baseline Transit Data Assessments, extensive research, and the aspirational nature of Version 1.0 of the California Minimum GTFS Guidelines, Caltrans and DRMT can provide technical assistance to transit providers in support of their Transit Data Improvement Strategy. This includes a combination of inbound service requests, targeted outbound assistance, and ongoing activities. See our Transit Data Helpdesk for more.

When will our data be assessed?

California transit providers can request an assessment at no cost at any time by contacting Include links to your Schedule and Realtime GTFS transit information, if available.

Transit providers can expect to receive their first assessment during the calendar month associated with your Caltrans district. For example, providers in District 1 will receive theirs in January, District 2 in February, etc. This ensures that providers can predict their schedule and that they will receive their assessments around the same time as their regional partner agencies.