Time-speed data points: Creep | Transient | Cruise

The Heavy Heavy-Duty Diesel Truck (HHDDT) schedule is a chassis dynamomter 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 (shown in Figure 1), transient (Figure 2) and (high speed) cruise (Figure 3).

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Figure 1. HHDDT Creep Mode

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Figure 2. HHDDT Transient Mode

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Figure 3. HHDDT Cruise Mode

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

Table 1
Statistics for HHDDT And UDDS Schedules
ParameterHHDDT CreepHHDDT TransientHHDDT CruiseUDDS
Duration, s25366820831063
Distance, mi0.1242.8523.15.55
Average Speed, mph1.7715.439.918.8
Stops/Mile24.171.80.262.52
Max. Speed, mph8.2447.559.358
Max. Acceleration, mph/s2.33.02.34.4
Max. Deceleration, mph/s-2.53-2.8-2.5-4.6
Total KE, mph23.66207.61036373.4
Percent Idle42.2916.38.033.4