US: Heavy-duty: HHDDT

The Heavy Heavy-Duty Diesel Truck (HHDDT) schedule is a chassis dynamometer test developed by the California Air Resources Board with the cooperation of West Virginia University.

The test consists of four speed-time modes, including idle, creep , transient and (high speed) cruise.

HHDDT Creep Mode HHDDT Transient Mode HHDDT Cruise Mode

Selected statistics for the particular HHDDT modes are compared with those for the UDDS cycle in the following table.