Standard: API 4088


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System Development Corporation (SDC) has performed a study to survey the characteristic use patterns of privately operated automobiles in six major metropolitan areas: Los Angeles, Houston, Cincinnati, Chicago, Minneapolis- St. Paul, and New York City. The study was conducted under jointly sponsored research contracts to the National Center of Air Pollution Control, Department of Health, Education, and Welfare, and the Coordinating Research Council, Inc. The purpose of the study was to obtain data necessary to develop composite average driving patterns that would serve as a basis for designing new teat cycles for vehicle emission control devices.

The findings of the surveys in each city have been published in a series of SDC Technical Memorandum, TM-(L)-4119, Volumes 0 through 6. This report presents a summary of the data from all six cities and some comparison between cities. Although strict interpretation of the results of classical hypothesis testing would seem to indicate that there are significant differences in the automobile utilization and trip descriptions, an examination of the individual and composite distributions of the various statistics indicates that there are many similarities. The results for each city showed that there were six different typical daily driving patterns which stood out clearly. The distribution of these daily patterns was quite similar among Houston, Cincinnati, Chicago, and Minneapolis-St. Paul, while New York differed in having more zero trip-days and Los Angeles had more multiple trip-days. Section Two presents the n-trip pattern days for each city and a discussion of their similarities and differences.

Automobile utilization, as characterized by trip start times, trip purposes, weekday-weekend division of trips, and types of routes traveled, demonstrates statistical similarities among all cities on weekends. While the statistical tests rejected hypotheses of homogeneity in most cases for weekday utilization, the number of daily trips, the route types, and the weekday-weekend distributions were somewhat similar for the four cities other than New York and Los Angeles. Section Three presents the distributions of the automobile utilization variables and an interpretation of their comparisons.

The trip descriptors compared were trip distance, trip elapsed time, stops with engine running, average speed, elapsed time between trips, indoor-outdoor parking between trips and overnight, and overnight fuel tank readings. While New York was different from the other cities in almost all respects, and the stops with engine running exhibited no similarities, the other cities were quite homogeneous in all except weekday elapsed time and average speed. These distributions are discussed in Section Four.

Tables S-1 and S-2 summarize the data gathered in each of the six cities for weekday and weekend automobile utilization. The data base for the survey includes 21,501 weekday trips and 7,842 weekend trips made in 946 private automobiles. In addition, we analyzed 809 weekday trips and 261 weekend trips made by about 20 taxicabs in the city of New York. A trip was defined as the period from engine-on to engine-off with the engine remaining off for more than five minutes. Tables S-3 and S-4 summarize the statistical variables that describe the average weekday and weekend trip in each of the six cities. In order to segregate data describing driving behavior on surface streets and on freeways, trips that involved freeway driving were divided into trip segments. Each segment included the part of the trip that was made on one type of road or the other. Generally, freeway trips contained three or more segments. Tables S-5 and S-6 summarize the data on segments of weekday and weekend trips for each of the six cities.

It should be noted that all of the tests used to compare the distributions are based on classical statistical techniques.

Organization: American Petroleum Institute
Document Number: api 4088
Publish Date: 1971-01-29
Page Count: 139
Available Languages: EN
DOD Adopted: NO
ANSI Approved: NO
Most Recent Revision: YES
Current Version: NO
Status: Inactive