While the US EPA and the National Highway Traffic Safety Administration released their long-awaited proposals last month for Phase 2 of the fuel economy rules governing tractor-trailers, a research paper finds that plenty of compliant trailers are already rolling down the highway today.
The proposals to further reduce GHG emissions by limiting fuel consumption will treat emission standards from trucks, tractors, engines and trailers separately, and do not require “integrated” tractor-trailer configurations. Pending public comments, the Phase 2 regs would begin taking effect for model-year 2018 trailers and MY 2021 tractors and trucks, and run through MY 2027.
As reported by Heavy Duty Trucking, Ben Sharpe, a senior researcher at the International Council for Clean Transportation explains that “box” trailers, which include long and short dry-freight and refrigerated vans, would need side skirts that cover their wheels, along with rear-end fairings and perhaps gap-reduction devices, to meet the Phase 2 proposals.
Those trailers would also use low-rolling-resistance tires and automatic tire-inflation devices.
“Non-box” and “non-aero” trailers, including flatbeds, tankers, dumps, livestock units and those with equipment that prevents use of aerodynamic aids, would need only easy-rolling tires and auto-inflation devices, according to Sharpe. An example of a non-aero trailer is a van with a rear liftgate that precludes a boat tail device.
The regulations are aimed solely at trailer manufacturers, aerodynamics-device manufacturers, and tire suppliers, Sharpe explains. While users are not regulated as such, they would be required to keep equipment in the condition as it was sold. This condition does not apply to replacement tires.
ICCT’s study of the proposals divides box trailers into seven categories, or “bins,” from a bare van with no aero improvers to “optimized” sets of skirts, boat tails and gap reducers, plus the tire improvements.
An eighth box-trailer category describes “exotic” trailers with smoother basic shapes, which could appear during the regulation’s time period, and might or might not be needed to meet Phase 2 regs. Teardrop-shaped trailers with curved roofs that probably fall into that class are running in the United Kingdom, news reports have said.
Phase 2’s targeted fuel and CO2 savings would start with 5% for a van with side skirts and a boat tail device, like many now running; move to 7% for what is currently a SmartWay Elite classification with more advanced equipment (which actually now requires a stiffer 9% improvement to be granted the Elite status); and reach 10% for trailers with optimized aero fairings, according to ICCT’s study.
Non-box and non-aero trailers would have no specific savings goals, but easy rolling tires that stay properly inflated would reduce mechanical drag and save fuel and CO2, the agencies’ reasoning goes.
Manufacturers would have to comply with the box-trailer regs by analyzing their models with an algebraic formula devised by EPA and NHTSA, Sharpe says. Manufacturers could “average” all vehicles on a sales-weighted basis, as car makers now do to meet corporate average fuel economy, or CAFE, standards. Or they could score each trailer model individually.
Scoring is based on the amount of CO2 in grams per ton-mile, he explains. Thus long, 53-foot trailers that typically carry 38,000-pound loads score better than short, 28-footers which tote 20,000-pound cargoes. The average load weights are based on government transportation data.
So why, asks HDT, won’t the agencies require integrated tractor-trailers that EPA has promoted in its SuperTruck development programs?
“They acknowledge that if you design a tractor-trailer together, you really optimize it,” Sharpe explained. “But they recognize that in the real world [of trucking], trailers get swapped out regularly.”