1. Require Zero Emission Bus Purchases. Mandate a fraction of bus purchases to be zero emission technology starting in 2018, and set a goal of complete transit fleet transition to zero emission technologies by 2040.

   Purchase requirements would be phased in every few years to meet percentage of fleet milestones that would establish the minimum number of zero emission buses in the fleet. Establishing periodic milestones is expected to provide flexibility for transit fleets to incorporate zero emission bus purchases in their normal procurement process.

2. Minimize Emissions from Conventional Fleet. Require use of renewable fuels and the cleanest available engines as soon as feasible. These proposed requirements will provide near-term NO_x, particulate matter, and GHG emissions reductions to help meet nearer term air quality, climate, and petroleum targets.

3. Provide Regional Flexibility for Zero Emission Buses. This would provide flexibility for transit agencies to plan for expanding a zero emission bus fleet and associated infrastructure in a more cost-effective manner. This would also result in larger concentrations of zero-emission buses that may allow for a more robust program with pooled resources and for strategic bus placements where the technology can be most effective and successful in current transit operations.

4. Innovative Transit Beyond Buses. ARB is exploring a strategy that would encourage transit fleets to work with metropolitan planning organizations (MPOs), regional Transportation Planning Agencies (RTPAs) or The California Department of Transportation (Caltrans) to develop regional plans for innovative transit beyond conventional transit operations as part of implementing Sustainable Communities Strategies (under SB 375) beyond improving bus efficiencies.

   Innovative transit technologies that improve efficiency and result in additional GHG reduction would potentially be recognized in implementing regional Sustainable Communities Strategies consistent with the requirements of SB375. Transit fleets that participate in implementing the plan might receive additional flexibility in meeting zero emission bus purchase requirements.

The discussion paper provides background on the need for emissions reductions; identifies technologies that are available for reducing bus emissions; and describes a number of issues staff is seeking to address with stakeholder input. These issues include:

• How to phase-in requirements for zero emission bus purchases in a manner that is consistent with existing purchase patterns?

• How existing funding programs could be improved to provide more certainty about available funding and funding levels?

• Should smaller transit fleets be given more time to phase-in zero emission buses?

• How to encourage deployments of fuel cell buses to bring them closer to commercialization?

• How conventional and plug-in hybrid buses should be included in the strategy?

• What are potential new and creative approaches to meet climate goals with innovative transit solutions beyond buses?

Approximately 32% of the heavy-duty transit vehicles operating in California are diesel-fueled. About 57% of the transit vehicles are operating on natural gas while six% are hybrids. For agencies that are operating diesel buses, diesel hybrids represent about 50% of bus purchases, even though there is no purchase requirement. Source: ARB. Click to enlarge.

Background. The 2000 Fleet Rule for Transit Agencies (Transit Fleet Rule) required reductions in both criteria pollutant emissions and exposure to air contaminants from urban buses and transit fleet vehicles. Urban bus fleets had to select either a diesel path or an alternative-fuel path. Agencies on the diesel path needed to meet requirements sooner, while agencies on the alternative-fuel path had to ensure that 85% of urban bus purchases were alternative-fueled.

To comply with the Transit Fleet Rule, transit agencies upgraded vehicles by retrofitting existing vehicles with aftertreatment systems; replaced older vehicles with new ones that come equipped with exhaust aftertreatment; or replaced with vehicles that have compressed natural gas engines. Many transit operators installed natural gas refueling infrastructure at their facilities. Transit fleets have been instrumental in developing technologies, such as compressed natural gas buses, exhaust after treatment systems, battery electric buses, and fuel cell buses.

In 2006, ARB amended the Transit Fleet Rule to include an advanced demonstration from the diesel path transit agencies, and to postpone temporarily the purchase requirement.

In 2009, the Board directed staff to report back to the Board with an assessment of zero emission technology and its progress towards commercialization, and to develop commercial readiness metrics to be used for purchase implementation criteria to initiate the zero emission bus purchase requirement.

This work will be completed as part of development of the Advanced Clean Transit regulatory proposal.