U.S. ports have been encouraging commercial fleets and independent owner-operators to participate in truck replacement programs in an effort to improve local air quality, but research shows that voluntary programs may only reduce a fraction of truck emissions. This is in contrast to mandatory programs, such as the Port of Los Angeles Clean Truck Program, which requires the use of clean trucks that meet the 2007 emissions standards and achieves greater emissions reductions.

The new peer-reviewed study by the Environmental Defense Fund (EDF) demonstrated that voluntary programs reduced emissions by one to four percent compared to a baseline of truck emissions before program implementation. Furthermore, the potential emission reductions are limited to 15 percent for particulate matter (PM) and 35 percent for nitrous oxides (NOx), two pollutants linked to serious health risks.

Some voluntary programs that have succeeded in modernizing local drayage trucks occurred after partnerships, such as the partnership of the Houston-Galveston Area Council and the Port of Houston in 2009. The Drayage Loan Program combined federal and state grants to provide drivers with low-interest loans and high value grants to replace older, polluting trucks with new, cleaner models. Short-haul drayage trucks have been found to contribute substantially to port area air pollution.

Find the EDF analysis titled, “Emissions reduction analysis of voluntary clean truck programs at U.S. ports,” authored by Elena Craft, PhD and Marcelo Norsworthy, in the July issue of Transportation Research Part D: Transport and Environment.