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Update - Feb 20, 2019 - CARB Notice (Download)

Latest CARB Info - Link


On June 19, the proposed Phase 2 GHG rulemaking was announced. The 1,329 page document covers both tractors and trailers for the first time. It is a joint proposed GHG stand- ard between EPA and NHTSA to improve the fuel efficiency of medium and heavy duty vehicles effective model year 2018 and beyond. This new Phase 2 program is estimated to cut emissions by 1 billion metric tons, conserve 1.8 billion barrels of oil, and lower fuel costs by over $170 billion over the lifetime of the vehicles covered.

The five primary greenhouse gases in the earth’s atmosphere are: water vapor, carbon dioxide, methane, nitrous oxide and ozone.

The new Phase 2 GHG rulemaking is divided into four regulatory categories:

  • Tractors
  • Trailer
  • Heavy-duty pick- up trucks and vans
  • Vocational vehicles (buses, refuse, concrete, etc.)

There are also separate standards for engines.

Trailers are recognized in the standard as an integral part of the tractor-trailer vehicle that significantly contributes to the emissions and fuel consumption of the tractor. The new proposed rule spells out cost-effective trailer technologies that can offer significant carbon dioxide and fuel use reductions for the vehicle. These technologies include: aerodynamic devices, low rolling resistance tires*, automatic tire inflation systems* and lightweight components.

*Non-box trailers (including platform/flatbed, tank, container chassis and other specialty trailers) would be required to use lower rolling resistance tires and automatic tire inflation systems

Trailers have been broken into five categories:

  • Highway box trailer shorter than 50’
  • Highway box trailer longer than 50’
  • Highway box refrigerated trailers longer than 50’
  • Highway box refrigerated trailers shorter than 50’
  • Non-box highway trailers

EPA/NHTSA has published an updated Greenhouse Gas Emissions Model for this Phase 2 rulemaking called the GEM model. It is a tractor-trailer computer vehicle simulation tool to determine if vehicles will meet the new standards. This new GEM program can be down- loaded at http://www.epa.gov/otaq/climate/gem.htm.