Development of the Texas Drayage Truck Cycle and Its Use to Determine the Effects of Low Rolling Resistance Tires on the NO _X Emissions and Fuel Economy

Trucks operating in inter-modal (drayage) operation in and around port and rail terminals, are responsible for a large proportion of the emissions of NO_X, which are problematic for the air quality of the Houston and Dallas/Ft. Worth metro areas. A standard test cycle, called the Texas Dray Truck Cycle, was developed to represent the operation of heavy-duty diesel trucks in dray operations. The test cycle reflects the substantial time spent at idle (~45%) and the high intensity of the on-road portions. This test cycle was then used in the SAE J1321 test protocol to evaluate the effect on fuel consumption and NO_X emissions of retrofitting dray trucks with light-weight, low-rolling resistance wide-single tires.

In on-track testing, a reduction in fuel consumption of 8.7% was seen, and NO_X emissions were reduced by 3.8% with the wide single tires compared to the conventional tires. Without considering the test-cycle idle periods, the reductions were 9.3% and 7.4% for fuel consumption and NO_X emissions, respectively.