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Emission Test Cycles

Chicago Transit Authority (CTA) Cycle

Time-torque-speed data points

The CTA (Chicago Transit Authority) test cycle is typically used for dynamometer aging of engines, engine components, or emission control devices. The graph (Figure 1) and the linked torque/speed data file represent a 5 minutes trace, which can be modified to suit the testing laboratory. The cycle is usually run continuously, multiple times in succession, for a period of tens or hundreds of hours.


Figure 1. CTA Cycle