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Trucks operating in inter-modal (drayage) operation in and around port and rail terminals, are responsible for a large proportion of the emissions of NOX, 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 NOX 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 NOX emissions were reduced by 3.8% with the wide single tires compared to the conventional tires.

The Texas Department of Transportation began using an emulsified diesel fuel in 2002. They initiated a simultaneous study of the effectiveness of this fuel in comparison to 2D on-road diesel fuel and 2D off-road diesel. The study included comparisons of fuel economy and emissions for the emulsion, Lubrizol PuriNOx®, relative to conventional diesel fuels. Two engines and eight trucks, four single-axle dump trucks, and four tandem-axle dump trucks were tested. The equipment tested included both older mechanically-controlled diesels and newer electronically-controlled diesels. The two engines were tested over two different cycles that were developed specifically for this project. The dump trucks were tested using the “route” technique over one or the other of two chassis dynamometer cycles that were developed for this project In addition to fuel efficiency, emissions of NOx, PM, CO, and HCs were measured. Additionally, second-by-second results were obtained for NOx and HCs.