A Statistical Characterization of School Bus Drive Cycles Collected via Onboard Logging Systems

Abstract

In an effort to characterize the dynamics typical of school bus operation, National Renewable Energy Laboratory (NREL) researchers set out to gather in-use duty cycle data from school bus fleets operating across the country. Employing a combination of Isaac Instruments GPS/CAN data loggers in conjunction with existing onboard telemetric systems resulted in the capture of operating information for more than 200 individual vehicles in three geographically unique domestic locations. In total, over 1,500 individual operational route shifts from Washington, New York, and Colorado were collected.Upon completing the collection of in-use field data using either NREL-installed data acquisition devices or existing onboard telemetry systems, large-scale duty-cycle statistical analyses were performed to examine underlying vehicle dynamics trends within the data and to explore vehicle operation variations between fleet locations. Based on the results of these analyses, high, low, and average vehicle dynamics requirements were determined, resulting in the selection of representative standard chassis dynamometer test cycles for each condition.In this paper, the methodology and accompanying results of the large-scale duty-cycle statistical analysis are presented, including graphical and tabular representations of a number of relationships between key duty-cycle metrics observed within the larger data set. In addition to presenting the results of this analysis, conclusions are drawn and presented regarding potential applications of advanced vehicle technology as it relates specifically to school buses.

Depot-Based Vehicle Data for National Analysis of Medium- and Heavy-Duty Electric Vehicle Charging

“…Findings regarding route distances were reported inDuran et al (2013), which analyzed over 1,700 route shifts from the school buses available in Fleet DNA that were available at its time of publication[36]. This study found those route shifts averaged 32 miles and had a large spread, from 1 to 128 miles; this result was similar to a 2011 study considering 861 route shifts in Fleet DNA finding an average length of 35 miles[37].…”

Review on Construction Procedures of Driving Cycles

“…The paper analyses the second-bysecond emission results of FTIR measurements to investigate which parts of the test cycles are causing the highest emissions. [70] The methodology of a large-scale duty-cycle statistical analysis are presented, including graphical and tabular representations of a number of relationships between key duty-cycle metrics observed within the larger data set in [71]. Examining a number of metrics associated with vehicle energy consumption and driving behaviour, statistical relationships between key metrics of interest were explored.…”

“…Examining the correlation between average driving speed and kinetic intensity, one observes a strong power correlation between the two variables. [71] Extensive duty-cycle statistical analyses are performed to examine and characterize common vehicle dynamics trends and relationships based on in-use field data in [72]. Having received in-use data, the data are processed using a series of semi-automated routines.…”