Integrating trailers into the U.S. Phase 2 HDV efficiency rule

This paper, “Recommendations for regulatory design, testing, and certification for integrating trailers into the Phase 2 U.S. heavy-duty vehicle fuel efficiency and greenhouse gas regulation,” summarizes recent ICCT research on the integration of trailers into Phase 2 of the U.S. regulations covering heavy-duty vehicle fuel efficiency and greenhouse gas (GHG) emissions. The guiding principle in this analysis is that the classification framework, as well as the testing and certification procedures, for trailers should be as closely aligned to that of tractors as possible. Recommendations for action include:

• Integrate trailers into the Phase 2 U.S. heavy-duty vehicle regulatory program to greatly increase the fuel and GHG reductions of the program. The approximate potential benefits from trailers are approximately 7–10% per tractor-trailer, as compared with the 17–23% per tractor from the Phase 1 program that excludes trailers.
• Make trailer manufacturers a directly regulated entity within the overall heavy-duty vehicle regulatory program for increased certainty that fuel-saving trailer technologies will be adopted and to provide regulatory clarity.
• Develop a trailer classification framework that facilitates improvements in aerodynamics, tire rolling resistance, and lightweighting in box trailers as well as improvements in tire rolling resistance for all trailer types.
• Align the testing and certification procedures for tractors and trailers as much as possible.
• For trailer aerodynamic testing, pursue an “A-to-B” approach in which an identical tractor is used to test both a baseline and an “enhanced” trailer in order to certify the enhanced trailer model’s aerodynamic bin level.
• Utilize a grams/ton-mile (and functionally equivalent gallons/ton-mile) certification metric for trailers that is identical to the metric used for tractors and vocational vehicles in the Phase 1 regulation.

These recommendations point toward a Phase 2 heavy-duty vehicle regulatory program for the U.S. and Canada that more comprehensively promotes known cost-effective technologies for tractor-trailers. The early voluntary efforts from the U.S. EPA’s SmartWay program as well as the California tractor-trailer GHG regulation have succeeded in driving trailer technology development, technology cost reductions, and increasing adoption of trailer technology. The regulatory approach recommended in this paper offers a natural extension of the same policy principles, but with wider fleet fuel savings and carbon emission benefits.

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