Studies of driving cycles for buses have been published in a number of papers, e.g., the Central Business District (CBD) and New York Bus (NY Bus) driving cycles. Such studies, however, cannot represent the actual driving environment of Seoul because of differences in road conditions and the volume of traffic. Thus, this study presents the development of a driving cycle for the city bus system of Seoul, the capital city of Korea.
A representative route is selected by means of a statistical analysis of the city bus routes in Seoul. Experiments are performed to measure velocity, road grade, engine speed, load conditions, gear-shift patterns, and vehicle acceleration in actual Seoul traffic. A simulation model is developed to evaluate a driving cycle on the basis of the measured data obtained. The coupling effect between velocity and acceleration is analyzed, as well as the coupling effect between road grade and vehicle acceleration. A driving cycle is then proposed based upon an analysis of parameters drawn from the experimental data.
The cycle is evaluated by means of simulation and a test that employs a chassis dynamometer. The evaluation is performed in relation to fuel economy, drivability, and engine operating conditions in both the proposed driving cycle and actual driving conditions. After several rounds of reconstruction, a city bus driving cycle for Seoul has finally been proposed. The final driving cycle consists of a velocity profile, road grade factors, and a timed approach to gear shift timing.
This final product is called the Seoul City Bus Driving Cycle (SCBDC). The running time of the cycle is 1,320 s with 344 s of idle time. The average velocity is 29.2 km/h, with a maximum of 67.0 km/h over a total distance of 7.86 km. The fuel economy in the SCBDC is 2.36 km/I, as opposed to 2.32 km/I for actual Seoul traffic. There were few differences in terms of velocity distribution, acceleration, road grade, and engine operating conditions between the SCBDC and actual Seoul traffic.