Log in | Subscribe

Emission Test Cycles

EPA Urban Dynamometer Driving Schedule (UDDS) for Heavy-Duty Vehicles

Time-speed data points

The EPA Urban Dynamometer Driving Schedule (UDDS) has been developed for chassis dynamometer testing of heavy-duty vehicles [40 CFR 86, App.I].

This test is also referred to as “cycle D”. The UDDS schedule was a basis for the development of the FTP transient engine dynamometer cycle. The HD-UDDS cycle should not be confused with the FTP-72/LA-4 cycle for light-duty vehicles, which is also called UDDS.

Figure 1. HD-UDDS Cycle

The following are basic parameters of the cycle:

  • Duration: 1060 seconds
  • Distance: 5.55 miles = 8.9 km
  • Average speed: 18.86 mi/h = 30.4 km/h
  • Maximum speed: 58 mi/h = 93.3 km/h