Development of the Federal Urban Driving Schedule

This paper reviews the development of the LA 4 road route, and discusses efforts directed toward development of a short repetitive dynamometer cycle based upon the road route Also described are the instrumentation, methods, and selection process used to obtain a speed profile of a typical drive over the 12 mile long route The methods used to shorten the speed profile to 7.5 miles, and to shorten the average trip length, while preserving trip description such as average speed, idle time, number of stops, etc., are explained. A measure of the correlation of emissions from vehicles driven over the EPA Urban Dynamometer Driving Schedule (UDDS) and over the full LA 4 driving schedule is provided.

The UDDS is a speed-trace consisting of 18 profiles. separated by idle periods of 0-39 s duration The schedule covers 7.46 miles in 1372 s for an average speed of 19.6 mph.