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Emission Test Cycles

Transit Coach Operating Duty Cycle (BAC)

Time-speed data points: CBD | Arterial | Commuter

The Transit Coach Operating Duty Cycle, Figure 1, was originally designed to measure heavy-duty vehicle’s fuel economy [SAE J1376, canceled 1997]. This cycle, also referred to as Business-Arterial-Commuter (BAC) to reflect its composite character, includes a sequence of the following segments performed on a chassis dynamometer:

  1. Central Business District (CBD) segment, Figure 2
  2. 300 second idle period
  3. Arterial segment, Figure 3
  4. CBD segment
  5. Arterial segment
  6. CBD segment
  7. Commuter segment, Figure 4
Figure 1. Composite BAC Cycle
Figure 2. CBD Segment
Figure 3. Arterial Segment
Figure 4. Commuter Segment

The following are characteristic parameters of the composite BAC cycle:

  • Duration: 2830 s
  • Driving distance: 22.53 km
  • Maximum speed: 88.5 km/h (55 mph)
  • Average speed: 28.9 km/h