California Transit Association



On Friday, December 14, the California Air Resources Board (ARB) adopted the Innovative Clean Transit regulation. The ICT regulation, which has been in development since spring 2015, requires large transit agencies to begin to purchase zero-emission buses (ZEBs) as soon as 2023, with the goal of transitioning all transit buses in California to zero-emission technology by 2040.

The regulation initially impacts standard transit buses, postponing the ZEB purchase mandate for non- standard buses (i.e. articulated, cutaway, over-the-road coaches) until at least 2026.

The main provisions of the ICT regulation are as follows:

  • Individualized ZEB Rollout Plans: The regulation requires large and small transit agencies to develop and submit a ZEB rollout plan by July 1, 2020 and by July 1, 2023, respectively.
  • ZEB Purchase Mandate: The regulation requires transit agencies to acquire a minimum number of ZEBs at the time of new bus purchases, based on the following schedules.

Large transit agencies:

  • 2023: 25%
  • 2026: 50%
  • 2029 and After: 100%

Small transit agencies:

  • 2023: N/A
  • 2026: 25%
  • 2029 and After: 100%

The regulation does not require the purchase of zero-emission articulated or cutaway buses or over-the-road coaches until at least 2026.

Importantly, state incentive funding, like HVIP, will only be available to transit agencies that purchase ZEBs before – or in excess of – the requirements established by the regulation.

  • Statewide Thresholds: The regulation includes a mechanism for encouraging the early elective adoption of ZEBs and postponing the purchase mandate. Under this mechanism: 
    • If transit agencies statewide have 850 ZEBs in operation and/or on order by December 31, 2020, the 2023 purchase mandate impacting large transit agencies (noted above) would be postponed until 2024.
    • And, if transit agencies statewide have 1,250 ZEBs in operation and/or on order by December 31, 2021, the 2024 purchase mandate impacting large transit agencies (noted above) would be postponed until 2025.
  • Low NOx Requirement: The regulation requires transit agencies to purchase low NOx engines, if available, for conventional internal combustion engine bus purchases.
  • Renewable Fuel Requirement: The regulation requires transit agencies to purchase renewable fuels when diesel or natural gas contracts are renewed.

The regulation authorizes transit agencies to request a one-year exemption from the ZEB purchase mandate to address the following issues:

  • Delays in bus delivery or infrastructure buildout;
  • The unavailability of ZEBs with sufficient range to meet a transit agency’s daily mileage needs;
  • The unavailability of ZEBs that meet Americans with Disabilities Act requirements or any other federal, state or local law, regulation or ordinance; and,
  • Financial hardship at the transit agency, including the inability to secure funding to offset the incremental cost of a ZEB over a conventionally-fueled equivalent bus.

The one-year exemption can be renewed by ARB’s Executive Officer if the issues persist.

The board resolution that accompanies the regulation directs ARB’s Executive Officer to provide the ARB Board with a comprehensive review of the regulation at least one year prior to the initiation of any ZEB purchase requirement. The comprehensive review will assess the following issues:

  • Cost, performance and reliability of ZEBs;
  • Availability of incentive funding;
  • Infrastructure necessary to support ZEB deployment;
  • Extent of job creation resulting from the rule;
  • Deployment status of ZEBs and related technologies; and,
  • Barriers to ZEB deployment.

The comprehensive review provides the ARB Board with an opportunity to adjust the ICT regulation, if necessary.