The US Environmental Protection Agency (US EPA) and the California Air Resources Board (CARB) are working together to develop proposed rules for on-road heavy-duty vehicle and engine regulation. A few of the anticipated changes include more stringent NOx standards, changes to test procedures, requirements for zero-emission vehicles in California, and the utilization of emerging technologies.
In January of this year, the US EPA issued an Advanced Notice of Proposed Rulemaking (ANPR) requesting pre-proposal comments on its Cleaner Trucks Initiative for highway heavy-duty vehicles and engines. The next step will be reviewing comments and publishing a Notice of Proposed Rulemaking (NPRM).
Revised standards are being driven by the significant contribution of heavy-duty vehicles and engines to NOx emissions and the need to compiy with National Ambient Air Quality Standards (NAAQS). The agency also acknowledged the potential for collaboration with CARB in preparing a 50-state standard and are looking at two paths to regulation; engine or chassis-certification of the entire vehicle.
Richard Corey, an Executive Officer with CARB, explained that the rule will likely include the following elements:
- “Significantly more stringent exhaust emission standards and test procedures for 2024 and subsequent model year engines, including 2027 model year standards approximately 90 percent lower than today’s standards;
- A new low-load certification test cycle that demonstrates emission control during sustained low-load engine operation, which constitutes a large fraction of how trucks actually operate in urban areas;
- Durability demonstrations at certification that correlate with in-use emissions performance experience;
- Revamping the current heavy-duty in-use testing (HDIUT) program to require better emission control and cover all modes of in-use operation;
- Increased regulatory useful life to more accurately reflect how long trucks are used today (for example, to 800,000 miles for the heaviest trucks); and
- Longer emission warranty coverage (for example, to 600,000 miles for the heaviest trucks) to help ensure that emission control systems are well-designed and built properly and make it more likely that emissions-related repairs are completed promptly.”