The EPA trailer standards, which exclude certain categories such as mobile homes, will begin to take effect in model year 2018 for certain trailers, while NHTSA’s standards will take effect as of 2021, with credits available for voluntary participation before then. Thestandards only apply to new trailers. There are no requirements for owners or operators to retire or retrofit trailers.

The Phase 2 standards maintain the underlying regulatory structure developed in the Phase 1 program, such as the general categorization of medium- and heavy-duty vehicles and the separate engine standards.

On 16 November 2016, EPA and NHTSA conducted a workshop on the certification process for trailers to comply with Phase 2 Greenhouse Gas Emissions and Fuel Efficiency Standards.

Under the existing Phase 2 program, there are four stages of standards for new trailers: MYs 2018, 2021, 2024, 2027+.

Regulated trailers include:

• Long-box dry vans (greater than 50.0-feet in length)
• Long-box refrigerated vans (greater than 50.0-feet in length)
• Short-box dry vans (50.0 feet and shorter in length)
• Short-box refrigerated vans (50.0 feet and shorter in length)
• Tank trailers designed to transport liquids or gases

• Flatbed trailers with continuous, flat platforms

• Container chassis (all lengths)

There are several types of standards involved in the Phase 2 trailer regulations:

• Design standards for flatbed trailers, tank trailers and container chassis and for box vans designated as “non-aero” require trailer manufacturers to install a certain level of lower rolling resistance tires and a tire pressure system (either TPMS or ATIS). The design standards do not require the use of any specific make or model of technology.

• Performance-based standards for box vans (other than “non-aero”). Manufacturers can meet the overall trailer performance requirements with any combination of technologies, including the use of aerodynamic improvements, lower rolling resistance tires, tire pressure systems (ATIS or TPMS) weight reduction, or other “off-cycle technology.” The performance standards do not require the use of any specific technology type, make, or model Manufacturers must demonstrate that the trailer meets the performance standard.

In light of the significant issues raised, the agency has decided to revisit the Phase 2 trailer and glider provisions. We intend to initiate a rulemaking process that incorporates the latest technical data and is wholly consistent with our authority under the Clean Air Act.

—EPA Administrator Scott Pruitt