Higher gross weight limits and longer combination vehicles (LCVs) would have significant benefits for many private fleet operations, according to a new study conducted by the Univ. of Michigan Transportation Research Institute (UMTRI) for the National Private Truck Council (NPTC). The increased efficiency of larger vehicles would also have a positive impact on the country's overall economy and environment, according to John Woodrooffe, the lead researcher on the study.
The study looked at three scenarios – increasing GVW limits to 91,000 lbs. and 97,000 lbs. for a single tractor and 53-ft. trailer combination, and longer combination vehicles (LCVs) with two 53-ft. trailers. After surveying NPTC membership on the estimated reduction in shipments and truckloads they might expect for each of these three scenarios to create a baseline, the researchers conducted in-depth analysis of seven fleets representing a cross-section of businesses, including wholesale and retail food, other retail products, building supplies and industrial supplies.
By reducing vehicle miles traveled, all three proposals offered reduced fuel and operating costs for the seven fleet operations, according to the study. On average, the LCV approach would lower fuel costs by 8%, while a 91,000-lb. GVW would cut fuel costs by 2.5% and 97,000-lb. GVW by 3.6%, Woodrooffe said during a presentation at NPTC's annual conference last week. Combining an LCV with a GVW increase to 91,000 lbs. would result in a 10.5% decrease in fuel costs, while an LVC/97,000-lb. GVW approach would yield an 11.7% drop in fuel costs.
If new technology was able to cut tractor-trailer fuel consumption by 10% that would result in a 0.67 MPG gain in average fuel efficiency for the fleets studied, according to Woodrooffe's calculation. The GVW and LCV approach would bring a 0.77 MPG gain without any new technology, he said.
Not only would fewer trips by larger trucks cut fleet operating costs, but it would have a positive impact on road congestion and lead to lower emissions, the report said. The 97,000-lb./LCV combination has the potential to cut trucking's fuel usage by 3 billion gallons a year and its annual CO2 emissions by 32.6 million tons, according to Woodrooffe.
The survey found that 56% of NPTC's membership weighs out under the current 80,000-lb. GVW limit and 34% cube out under current length limits. Overall they estimated that higher GVWs would result in 10% fewer truck trips for their operations and LCVs in 6% fewer trips. Combining the two approaches could reduce their truck trips by 16%, according to the UMTRI study.
Moving to larger trucks would not be without costs, the study found. For fleets, transitioning from two-axle trailers to three-axle ones to accommodate the higher GVWs "would require a significant cash investment." New fleet costs for LCVs would be relatively minor, according to the study, although they would most likely require investment in additional driver training.
Using tri-axle trailers would eliminate concerns over heavier trucks deteriorating roadways, but investment in bridges to handle the extra weight could be an issue, Woodrooffe said. He also pointed out that the industry would have to address safety questions raised by LCVs through further studies.
"For more than a decade, NPTC has supported modification of federal truck size and weight restrictions in a manner that will improve shipper and carrier productivity," said Gary F. Petty, NPTC president & CEO. "While there has been ample anecdotal evidence in the private fleet community that larger trucks would mean greater productivity for the businesses operating them, there has not been, until now, a study that helps support the case for changes in the law based on an independent research analysis of a sample group of companies."
