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Emission Test Cycles

Central Business District (CBD)

Time-speed data points

The Central Business District (CBD) Cycle is a chassis dynamometer testing procedure for heavy-duty vehicles [SAE J1376]. The CBD cycle is part of the Advanced Bus Design cycle that was created by the US Department of Transportation and the Urban Mass Transit Association as part of the specifications for assessing bus performance.

The CBD cycle represents a “sawtooth” driving pattern, which includes 14 repetitions of a basic cycle composed of idle, acceleration, cruise, and deceleration modes. Vehicle speed over the duration of the CBD cycle is shown in Figure 1.

Figure 1. CBD Driving Cycle

The following are characteristic parameters of the cycle:

  • Duration: 560 s
  • Average speed: 20.23 km/h
  • Maximum speed: 32.18 km/h (20 mph)
  • Driving distance: 3.22 km
  • Average acceleration: 0.89 m/s2
  • Maximum acceleration: 1.79 m/s2