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38 TABLE 11 SUMMARY STATISTICS ON PROFESSIONAL EXPERIENCE OF SAFETY-MANAGER RESPONDENTS Statistic Range Median Mean StDev Question (32) Number of years experience as carrier Safety 2 to 45 10 13.2 9.1 Manager or Human Resource Manager (33) Total years experience in commercial truck/bus 5 to 62 22 24.0 12.6 operations Note: StDev = standard deviation. their fleets. Table 12 provides summary statistics of their included opinion items, but no items on their operational answers. practices, because they are not so involved. The data from this other-expert survey were of interest, although, as it (1) gauges There are no definitive population statistics to compare expert opinion on questions, (2) points toward areas perhaps with the previously cited respondent individual and fleet sta- deserving more consideration, and (3) is a way of identifying tistics. Nevertheless, it is clear that survey respondents gener- ongoing research relating to project topics. ally were more experienced than most individuals with motor carrier safety management responsibilities, and that their fleets were generally much larger than average. This reflects the Questionnaire Design and Content trend of larger fleets being overrepresented at virtually all national and regional safety conferences, and as active mem- The other-expert survey questionnaire was similar to that bers of national and state truck and bus transport organizations. for safety managers. It consisted of the following general sections: Question 35 asked respondents to select the truck or bus operation type that best characterized their fleet. The num- · A brief statement of the study and survey purpose, with bers of responses in each category are listed in Table 13. a confidentiality assurance; Although the question asked for "the" best characterization, · Two related five-choice questions on general factors many bus safety managers selected two choices ("g" and "h" affecting safety and crash risk (used on paper form only); in Table 13). Therefore, that dual selection is listed later as a · 16 driving situations or operational practices, each rated separate choice. on a -3-to-+3 Likert scale (-3, -2, -1, 0, +1, +2, +3) for effect on fleet safety; · A multiple choice question on the general relationship OTHER-EXPERT SURVEY METHODS between carrier efficiency and safety; · An open "comments" space; and The secondary project survey was of other experts in motor · Two questions on respondent's years of motor carrier carrier safety. These individuals were primarily professional safety-related experience and on specific types of posi- associates of the principal project investigators. They were tions held. known personally or through their jobs or other professional activities. They included professionals in government, indus- try trade associations, other industry roles (e.g., safety con- Questionnaire Distribution and Analysis sulting), and research. Many of these individuals are actively involved in other TRB truck and bus safety activities. Even The other-expert survey was administered only online through though these individuals are highly knowledgeable, they are TRB's online survey service. The survey solicitation was sent regarded as secondary respondents because they are (by defi- by means of e-mail to 134 individuals, with a second e-mail nition) not currently carrier practitioners. Their survey forms reminder sent several weeks later. A total of 32 online surveys TABLE 12 SUMMARY STATISTICS ON SAFETY-MANAGER RESPONDENT FLEET SIZE Statistic Question Range Median Mean SD (34) Approximate number of power units currently 14 to 15,000 112.5 866 2,201 in fleet