July 11, 2016 4:00 AM, EDT

Editorial: The Coming of Phase 2

This editorial appears in the July 11 print edition of Transport Topics. Click here to subscribe today.

Within several weeks, we could see the final form of Phase 2 of greenhouse-gas limits for heavy- and medium-duty trucks. That should not be confused with the rollout of the second half of Phase 1 GHG regulations on Jan. 1 — although the timing seems almost guaranteed to generate confusion.

The march of environmental regulation continues, and the complexity of federal mandates and the trucking equipment used to comply with the rules rises as the level of permissible emissions falls.

Phase 1 addressed trucks and their engines in two stages, 2014 and 2017. Phase 2 is expected before the end of July, according to two sources within the truck-making industry (see story, p. 3), and if it’s similar to the proposed form, it will add regulation of truck trailers and maybe glider kits, too. The number of stages for trucks also could rise to three: 2021, 2024 and 2027.

The rule is under review by the White House Office of Management and Budget, and when OMB is done, officials will send it back to the Environmental Protection Agency and the National Highway Traffic Safety Administration for formal publication. Here are some things to look for in the final rule:

• Three stages are better than two. We hope the administration does not accelerate adoption to 2024, which is an option. The engineering challenge is substantial and should not be rushed.

It’s not enough simply to tamp down carbon dioxide and other GHGs. This equipment has to work reliably and be durable as it moves freight around the nation. An expensive, zero-emissions truck that’s always in a maintenance shop does no one any good. We know that truck and engine makers appreciate this, and we hope EPA does, too.

• Concentrate on GHGs only right now. Our emissions story notes that a dozen state and local agencies have asked EPA to write a national rule lowering emissions levels of nitrogen oxides by 90% during the same timeline as Phase 2.

The regulatory NOx ceiling plunged by 95% from 1998 to 2010. Engineers have been optimistic about maintaining low NOx levels while slicing even further into GHG production, but reducing both gases simultaneously is a recipe for disaster.

• Be careful on trailers. Loading up aerodynamic requirements on trailers that run only in metropolitan areas is largely pointless. Aim the solutions where they’ll do the most good.