"Four years ago, in August 2011, U.S. EPA and the National Highway Traffic Safety Administration announced the first federal program to cut carbon emissions from the nation's biggest vehicles by raising the fuel standards those heavy-duty fleets must meet.

The agencies implemented that plan -- the Heavy-Duty National Program -- last year.

In the next few days, the agencies are expected to roll out a new proposal, the second phase of their plan to lower emissions from heavy-duty vehicles like tractor-trailers, city buses, delivery vans and cement mixers."

Benjamin Hulac reports for ClimateWire June 17, 2015. [2]