National Academies Press: OpenBook

Driver Selection Tests and Measurement (2012)

Chapter: CHAPTER SIX Conclusions

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Suggested Citation:"CHAPTER SIX Conclusions." National Academies of Sciences, Engineering, and Medicine. 2012. Driver Selection Tests and Measurement. Washington, DC: The National Academies Press. doi: 10.17226/14632.
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Suggested Citation:"CHAPTER SIX Conclusions." National Academies of Sciences, Engineering, and Medicine. 2012. Driver Selection Tests and Measurement. Washington, DC: The National Academies Press. doi: 10.17226/14632.
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Suggested Citation:"CHAPTER SIX Conclusions." National Academies of Sciences, Engineering, and Medicine. 2012. Driver Selection Tests and Measurement. Washington, DC: The National Academies Press. doi: 10.17226/14632.
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Suggested Citation:"CHAPTER SIX Conclusions." National Academies of Sciences, Engineering, and Medicine. 2012. Driver Selection Tests and Measurement. Washington, DC: The National Academies Press. doi: 10.17226/14632.
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Suggested Citation:"CHAPTER SIX Conclusions." National Academies of Sciences, Engineering, and Medicine. 2012. Driver Selection Tests and Measurement. Washington, DC: The National Academies Press. doi: 10.17226/14632.
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Suggested Citation:"CHAPTER SIX Conclusions." National Academies of Sciences, Engineering, and Medicine. 2012. Driver Selection Tests and Measurement. Washington, DC: The National Academies Press. doi: 10.17226/14632.
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59 CHAPTER SIX CONCLUSIONS ment (R&D) needs for greater knowledge and more useful driver assessment tools. DRIVER INDIVIDUAL DIFFERENCES AND SAFETY Chapter two described driver characteristics and personal dimensions with known relationships to safety-related behavior and especially to driving crash risk. This sec- tion highlights some major conclusions from that chapter. Selected, major citations are provided here; additional cita- tions are found in chapter two. Two psychological “metaprinciples” are related to indi- vidual differences and to behavioral consistency. These metaprinciples can be considered two sides of the same coin, because people differ greatly in safety-relevant ways and many of these differences are enduring. They are underlying rationales for emphasizing driver selection in motor carrier safety management. Federal minimum qualifications for commercial drivers encompass driver basic skills, driving and other personal history, and medical conditions, but do not address all per- sonal characteristics relevant to driving safety. Large indi- vidual differences in driving safety exist within almost any group of drivers, including those meeting all legal require- ments for commercial driving. Literature indicates that people differ from each other along many different dimensions related to heredity, devel- opmental environments, chronic life conditions, or a combi- nation of these. By and large, the root causes of individual differences are not of primary interest to employers because their effects already exist when employees present them- selves for hire. Evidence points to the following human trait categories as being most relevant to driving safety, and thus of greatest potential interest for commercial driver assessment: • Personality, including behavioral tendencies and attitudes • Psychomotor skills and cognitive functions • Medical status and conditions • Behavioral history • Mental ability. This report has reviewed the academic, commercial, and industry literature on tests, measurements, and other proce- dures used by motor carriers to select safe commercial driv- ers. It documented the large individual differences in driver crash risk, based on a previous synthesis (CTBSSP Synthesis 4) and more recent findings. It presented evidence relating to individual driver traits relevant to safety, and described ways that those differences are being assessed as part of hiring decision making. The study determined that personal and psychological dimensions related to safety can include— • Demographics (e.g., age and gender) • Driving knowledge and skills • Personality (e.g., aggressiveness, sensation-seeking, stress levels) • Risk perception and attitudes • Psychomotor skills (e.g., reaction time) • Medical status and conditions, including fatigue susceptibility • Behavioral history • Mental abilities. Individual differences in safety have been recognized as creating the need for valid employee assessments and selection procedures in particular. A variety of assessment procedures have been included under the rubric “tests and measurements” for purpose of improved driver hiring. These include resume evaluations, application forms, ques- tionnaires, driving observations, review of driving and other public records, biodata, interviews, mental ability tests, physical ability tests, personality and attitude inventories, medical histories, and medical examinations. This report reviewed the nature, use, and safety-effectiveness of these selection procedures. Surveys and interviews with carrier safety managers, and surveys of other experts were used to obtain information from motor carriers on underlying driver characteristics relevant to risk and how best to assess them. The project surveys were convenience samples of available individuals sufficiently motivated to take the time to partici- pate; they should not be regarded as being representative of larger populations. The following sections synthesize findings and draw major conclusions relating to driver individual differences, available and actual industry practices to improve driver selection, suggested practices, and research and develop-

60 Personality includes any persistent tendency or consistency in a person’s behavior or psychological makeup. Personal- ity traits are consistent tendencies in emotional adjustment, interpersonal relations, motivation, attitudes, and behavioral “style.” They are “deep individual characteristics, most often biologically rooted, that determine the broad emotional and behavioral orientations of the person” (Thiffault’s Towards a Strategy Targeting Human Factors in the Motor Carrier Industry in Canada). Psychological consistencies extend in two dimensions: consistency over time and consistency across diverse situations. Personality affects road safety through a person’s driving “style” and through specific behaviors and abilities. Few personality traits can be diagnosed as defini- tively as physical traits or medical conditions. Rather, they are descriptive constructs that may overlap. Those most relevant to safety include impulsivity/risk-taking, sensation-seeking, aggressiveness/hostility, Type A personality, conscientious- ness, agreeableness, and emotional stability. The first four have negative implications for safety, whereas the last three have positive implications. Along the extraversion-introversion con- tinuum, introversion is generally associated with lower risk. Personality contributes to attitudes—positive or negative evaluations of particular objects of thought, such as specific safe driving behaviors. Ajzen’s “The Theory of Planned Behavior” suggests that attitudes combine and interact with perceived social norms and behavioral control to determine intentions, which become behaviors. Well-constructed ques- tionnaires can assess individual differences in safety atti- tudes, and thus can be predictive of driving safety. On the surface, one might expect psychomotor skills to be highly predictive of driving success. Driving is an active sensorimotor task that requires accurate perception, quick thinking and decisions, and precise execution of maneuvers. Yet dynamic psychomotor abilities are not highly predictive of crash rates across the wide range of drivers. Safe driving appears to primarily reflect behavioral habits, choices, and temporary states rather than performance capabilities. The current survey findings were consistent with this conclu- sion. Psychomotor skills and cognitive functions are bigger concerns when drivers have serious medical conditions or impairments from past drug or alcohol use, or when their age raises the question of whether they will be subject to significant health or psychomotor changes. Medical conditions can affect driving safety in several ways, most obviously through catastrophic performance fail- ures while driving. In the Large Truck Crash Causation Study (LTCCS), truck driver physical failures, primarily asleep-at- the-wheel and heart attacks, were the Critical Reason (prox- imal cause) of 12% of truck at-fault crashes and 6% of all truck crashes. Sleep apnea and circulatory disease appear to be the driver medical conditions of greatest concern in com- mercial transport. There are marked individual differences in susceptibility to drowsiness, related in part to sleep disorders. Behavioral history includes past driving events and non- driving events. A driver’s history of crashes, violations, and other incidents is a well-documented predictor of future crash involvements and whether the driver will be at fault in future crashes. Past traffic violations seem to be a better predictor of future crashes than are past crashes themselves, because the former are more numerous (and thus more statistically reliable) and because they more clearly imply misbehavior and fault. Further, attitude inventory studies show that a slack attitude toward road rules and violations is strongly associated with poor driving behaviors and relative unconcern about crash risks. In regard to past crash involvements, there are reasons for considering single-vehicle crash involvements a clearer sign of risk than multivehicle crash involvements. In the LTCCS, truck single-vehicle involvements were much more likely than at-fault multivehicle involvements to involve driver asleep at the wheel, physical failure (e.g., a medical event), excessive speeds, aggressive driving (as an associated fac- tor), response execution errors, and vehicle maintenance failures (for which drivers are responsible). In contrast, many multivehicle crashes are triggered by a less egregious error, such as “looked but did not see.” Histories of nondriving criminality are associated with elevated crash and violation risk. Commercial drivers with criminal backgrounds also create security issues for carri- ers. The association of criminality and unsafe driving may be the result of the antisocial personalities and social devi- ance of some people with criminal histories. This behavior disorder is strongly associated with risk. The relation of poor credit history to crash risk is unclear. Motor carriers per- forming credit checks on their drivers justify the practice based primarily on security concerns. Intelligence and component mental abilities like spatial and mathematical reasoning appear to have some association with safety. Associations are more apparent at the extremes than across the middle ranges of mental abilities. More intelligent drivers appear to make more rational risk choices, better man- age their time, and better balance the demands of their jobs. One method for carriers to improve their safety is to improve their driver retention. For a variety of reasons, driv- ers with longer company tenures tend to be safer. Many of the personal traits associated with safe driving are also asso- ciated with retention. They include higher mental abilities, and conscientiousness and agreeableness. DRIVER SELECTION TOOLS AND PRACTICES This study used three major sources of information on cur- rent driver selection tools and practices in the truck and bus transport industries: the literature and product review

61 of driver selection tests and measurements (chapter three), the project safety manager survey (chapter four), and the case studies based on follow-up safety manager inter- views (chapter five). This section highlights some major conclusions from these chapters. Selected major literature citations are provided here; previous chapters contain addi- tional citations. Carriers must, at a minimum, take certain actions to ensure that any driver they hire meets federal qualifications. These actions, and required records of them, are specified in 49 CFR 391.51 and summarized in the 2008 FMCSA A Motor Carrier’s Guide to Improving Highway Safety. In practice, these minimum actions are combined with volun- tary company actions to form an overall system for hiring. Often this takes the form of a sequence of steps or multiple hurdles approach. The following are four generic rules for selecting the highest quality employees: 1. Target high-quality applicants. 2. Attract as many applicants as possible. 3. Use multiple, validated selection tools and methods. 4. Be as selective as possible. Job analysis is usually the basis for valid selection tests. A job analysis document helps carriers to identify the most important and valid elements of their selection process. These selection elements are predictors of job performance. Validity is the degree to which a test actually measures what it purports to measure. A test’s validity is determined in contexts such as content validity, construct validity, and cri- terion-based validity (predictive or concurrent). Document- ing a test’s predictive validity, or its validity coefficient in relation to job performance, is the best way to legally justify its use. Employers have an ethical and a legal duty to treat appli- cants for employment fairly. Several laws shape this legal duty, the most important of which is the Fair Employment Practices Act, also known as Title VII of the Civil Rights Act of 1964, as amended by the Equal Employment Opportunity Act of 1972. This law requires that employers not discrimi- nate in hiring, promotion, wages, training, or any other term, condition, or privilege of employment, according to the race, color, religion, sex, or national origin of the affected persons. These categories are the “protected classes” of individuals under the act. Adverse impact on a protected class occurs when a protected group is selected at less than 80% of the rate at which nonprotected applicants are selected. When this happens, employers must be prepared to examine, docu- ment, and defend their selection tests and other assessment procedures. A 2000 DOL guide helps employers to develop and use assessment tests fairly and legally. Obtaining commercial driver records is not a “test” in the usual sense, but it functions in the same manner as a screen- ing tool. Carriers are obliged to review state MVRs for traf- fic violations and convictions. The new federal PSP allows carriers to voluntarily access crash and roadside inspection data as well. Carriers are required by law to ensure that drivers meet medical qualifications, but meeting this requirement does not eliminate their concerns regarding crash risk and car- rier liability. Whether a medical condition is identified as the direct cause of a crash or is merely suspected as an asso- ciated factor, carriers have high liability exposure when unhealthy drivers are involved in crashes. Sleep apnea and cardiac conditions, both associated with physical failures (nonperformance) while driving, are among the primary health concerns about drivers. This report described a number of commercially avail- able tests marketed for use for selecting safe fleet drivers, or that could be considered candidates for such use. Tests were described in terms of the personal traits they seek to measure, how they are administered, test content, and key findings relating to their validity. However, no selection test or other product or service was formally evaluated for this report. Specific products and services were described as examples for reader edification. No endorsement of any product or service by the authors or by TRB is implied or intended. The following section, however, does suggest con- sideration of several types of selection tests. This project included convenience sample surveys of both current carrier safety managers and other experts in truck and bus safety. Survey findings cannot be considered repre- sentative of larger subject populations such as “all motor car- rier safety managers” because the sample spaces consisted of individuals already involved in national safety organiza- tions and because only a minority of potential respondents actually completed the surveys. Thus, survey findings reflect only the self-selected, safety conscious individuals who responded. Nevertheless, survey data reveal the rela- tive opinions of respondents on various driver risk factors and driver selection practices. Moreover, respondents were highly experienced; they had an average of 12 years expe- rience as safety managers and 23 total years experience in CMV transport. Respondents viewed both enduring and temporary char- acteristics of drivers as stronger determinants of crash risk than nondriver factors, including vehicle characteristics, roadways, and weather. Their views on the most important carrier practices were even more telling vis-à-vis the top- ics of this report. Carrier safety managers regarded driver assessment activities, including driver selection and postse- lection evaluation, to have greater effects on safety outcomes than other nonassessment management activities. The latter

62 included driver preparation (prejob training), company com- munications (e.g., safety meetings), and company rewards and discipline. Safety managers rated 12 driver personal or psycho- logical traits with regard to their perceived association with crash risk. Traits receiving the highest scale ratings included aggressive personalities, risk-taking personalities, and poor vehicle handling. Two with low perceived associations with crash risk were introverted/unsociable and poor English lan- guage skills. The ratings of other expert respondents were in general similar to those of safety managers. One factor rated by other experts as having a high association with crash risk (but which was not included on the safety manager form) was driver sleep hygiene habits. Safety managers were also asked about their use of vari- ous selection practices beyond those legally required. The average respondent used 6 of the 13 practices listed. Hir- ing practices receiving the most favorable ratings included the road and range driving tests, computer-based dynamic tests (though used by only a few respondents), personality questionnaires, and questionnaires about driving behaviors. Checking credit history and rating received the lowest aver- age rating. Ten follow-up structured interviews were conducted with volunteer respondents. Each was summarized in a car- rier case study write-up focusing on successful, innovative driver selection practices. Chapter five provided these nar- ratives. Five innovative practices were highlighted for each carrier, with other successful practices also described. Many of these are incorporated into the following section. REPORTED EFFECTIVE CARRIER PRACTICES This report focused on carrier practices in the areas of driver selection and evaluation. Driver assessment activi- ties interact with other carrier safety activities such as train- ing, communications, and behavioral safety management. Newman et al. in “Safety in Work Vehicles: A Multilevel Study Linking Safety Values and Individual Predictors to Work Related Driving Courses” measured both the safety values of individual drivers and the supervisory practices applied to all drivers in test fleets. They found that indi- vidual driver attitudes (e.g., toward rule violations) were predictive of safety, but that “across-the-board” effects were associated with fleet manager and first-line supervi- sor behaviors. Drivers reported fewer accidents when they were motivated by company practices to drive safely. This motivation was related to both fleet manager and direct supervisor behaviors and perceived safety values. Effec- tive fleet management practices seem to bring out the best and minimize the worst in drivers. Perhaps the simplest way to maintain a high-quality driver pool is to create a positive, professional, and rewarding work environment where driver jobs with the company are val- ued. This produces the situation in which driver recruitment efforts attract a large number of highly qualified applicants, which in turn allows a carrier to be highly selective in its hiring. A low selection ratio (i.e., hiring a small percentage of applicants) almost always ensures high-quality employ- ees, although another essential element is selection accuracy. Selection accuracy means using a regimen of valid selection procedures that truly capture the persistent driver character- istics most relevant to safety. Test characteristics such as reliability and validity underlie the legal requirements tests must meet. Treating employees fairly in selection and other assessments is not just a matter of ethics. It is the law, and guidelines promulgated by the EEOC must be followed if companies want to avoid a discrimina- tion lawsuit from the government or affected parties. Rigor- ous record keeping is essential, especially for companies with more than 100 employees. To help companies correctly design and use selection tools, the U.S. DOL (2000) has promoted 13 principles and best practices, described in chapter three. The value of these principles and practices extends beyond employee selection; they also related to post-hire assessments (e.g., for promotions) and employee training and development. Selection and hiring of commercial drivers starts with ensuring that they meet all legal requirements of the FMC- SRs. The process includes required hiring procedures and record keeping as well as certification that hired drivers meet licensing and medical qualifications. The project review of individual differences (chapter two), selection tests (chap- ter three), surveys (chapter four), and case studies (chapter five), as well as past reviews, suggests the following as com- mon and beneficial carrier practices: • Using multiple assessments to try to capture a variety of safety-relevant characteristics; trying to assess the “whole person.” • Using the new FMCSA PSP service. • Conducting a fresh and updated carrier assessment of driver medical condition, regardless of driver medical qualifications status. This may involve follow-up tests such as sleep studies. • Reviewing driver records with special focus on egre- gious violations (e.g., reckless driving). • Checking criminal background as it is relevant to both security and safety. • Assessing past crashes in regard to preventability and, when possible, specific causes. • Conducting a road and range driving test of every applicant using a standardized checklist or rating form. • Conducting a standardized interview designed to tap key driver safety-related traits.

63 • Assessing, through interviews or questionnaires, driver personality traits such as aggressiveness, impulsivity, conscientiousness, agreeableness, manageability, and attitudes toward risk. • Treating signs of driver hostility and anger toward the law or toward rules as red flags. • Selecting for retention as well as for safety. Driver employment longevity is generally associated with safe driving, in part because personal characteristics asso- ciated with these two outcomes overlap. • Putting as much information on company websites as possible about driver requirements and specific hiring procedures. • Maintaining a detailed and comprehensive assessment file for each driver. • Requiring a probationary period for new hires. • Conducting internal studies to document and validate selection procedures and their relevant to employment success. In addition to these established practices, this project has reported research, survey, and interview evidence of the potential value of the following: • Testing physical ability to perform job component tasks (e.g., carrying, lifting, climbing). • Testing “baseline” dynamic performance using a sim- ulator or computer-based test when long-term driver functional capacity is a concern (e.g., when many older drivers are hired). • Validating inventory questionnaires (e.g., on attitudes, values, and behaviors) on existing drivers and then using them in new driver selection. • Understanding that some desirable human traits like decisiveness, assertiveness, and high-energy level may not be necessary for success as a driver. • Using a job satisfaction/job choice inventory, particu- larly if validated against current employees. • Observing or otherwise discerning driver safety belt use as a supplemental assessment of driver risk-taking tendencies. • Giving extra scrutiny to single-vehicle crashes seen in crash records. In general, single-vehicle crashes sug- gest a greater risk of driver medical problems, fatigue susceptibility, and misbehaviors. • Using a mental abilities test as a supplement to other assessments, particularly if also relevant to nondriving tasks (e.g., record keeping, trip planning). Drivers with higher mental abilities tend to be safer and better bets for longer retention. • Joining or forming a consortium of similar carriers who meet regularly to share information about improving safety and reducing losses. In such consortia, carriers can share documentation and validation information on improved selection methods. RESEARCH AND DEVELOPMENT NEEDS Research finds new knowledge; development creates new tools. The literature review, survey, and case studies done for this synthesis have revealed opportunities for R&D to contribute to better commercial driver selection and higher quality drivers on the road. Most research would seek to define more sharply driver traits with relationships to safety. Most development would be on tests and other assessments usable by carriers or others to screen drivers for hire or for specific duties after hire. The latter might include driving tanker trucks or longer combination vehicles, which require greater skill and are generally higher paying. The relative lack of assessment R&D relating specifically to commercial drivers is a barrier to carrier use of many promising selec- tion methods. One study already under way is the FMCSA-funded Com- mercial Driver Individual Differences Study. This study, just beginning at the time of this writing, is using a case-control methodology. It will compare multiple characteristics of crash- or violation-involved drivers (cases) to other drivers without histories of unsafe driving (controls). Per the project request for proposal, the study includes medical examina- tions and a battery of psychological and behavioral history measures administered to 21,000 drivers to identify about 3,000 cases and 3,000 controls. Extreme groups based on risk will be investigated to maximize the contrast between groups and thus the likelihood of meaningful findings. The comparison of the highest-risk drivers to the lowest-risk ones will permit the derivation of odds ratios and other sta- tistics quantifying the risks associated with various driver characteristics. Factors to be incorporated include driver age, gender, height/weight, waist and neck size (for calcu- lating BMI), marital status, number of children, education, primary language, driving experience, carrier characteris- tics, driving exposure (day and night), safety belt use, crash and violation history, training, medical history, medication use, sleeping habits, caffeine intake, health-related lifestyle (smoking, alcohol, diet, and exercise), and life stress events. Figure 8 in chapter three contains a basic model of employee selection and the conceptual relation between the selection ratio and employee quality; the smaller the per- centage of applicants selected, the higher the general quality of employees selected. Currently, freight volumes are ris- ing and carriers need more drivers. The commercial driver shortage could reach 350,000 in just a few years. The current gradual economic upturn and other factors are likely to keep the driver shortage high over the next decade. Unfortunately for safety, this may make it harder for most carriers to be highly selective in the hiring and, in the process, take advan- tage of available and emerging tools for selecting good driv- ers. Lack of selectivity is a strong supply-and-demand-based barrier to more rigorous employee selection. Research and

64 other innovation could demonstrate ways to make the com- mercial driver job more attractive, thus increasing applicant pools and lowering selection ratios. This in turn would raise the quality of drivers hired. There would be benefits for both individual carriers and the industry as a whole from such research on driver recruiting approaches. A sad irony is that the transport industry faces a growing driver shortage even though overall unemployment percentages are among the highest in recent history. Research is needed to verify distractibility as a trait con- struct and to determine whether it can be discerned through testing. New naturalistic driving data on truck drivers veri- fies LTCCS evidence of the large role distraction plays in crash risk. WayPoint, discussed in chapters two and three, is a 4-minute Internet-based sensorimotor test in which sub- jects “connect the dots” amid some distracting visual icons. Based on findings with both truck and car drivers, the devel- oper of WayPoint has suggested distractibility as a distinct driver trait with a U-shaped relation to driving safety. A large decrement in performance in the presence of the icons suggests that the individual is highly distractible by driving- related stimuli like billboards and cell phone conversations. At the other extreme, little or no decrement in performance (undistractible) suggests that the individual has “tunnel vision” and might not notice peripheral or surprise events. Both extremes are potentially unsafe, while the middle of the distractibility scale is said to be ideal. This hypothesis is interesting and timely given current national concerns about distracted driving. Distractibility as a human trait deserves further research. A small driving simulator study by Kass et al. (2010) explored individual differences in distractibility but not the WayPoint hypothesis. It assessed subjects’ ten- dencies toward attention difficulties using a series of ques- tionnaires and correlated the results with driving behaviors and crashes on the simulator. Although no crash effect was seen, the independent measures of distractibility did predict lane breaks and excessive speeds on the simulator. The following R&D need and opportunity, based on sleep research and articulated in CTBSSP Synthesis 4 on high-risk drivers, still exists today: There is a specific development opportunity relating to the identification of individuals with high susceptibility to fatigue while driving…. [T]here is compelling evidence of wide individual differences in fatigue susceptibility, and further evidence that these differences persist over time. Given the essential role played by vigilance in driving, it is likely that some individuals are simply constitutionally ill-suited to long-haul commercial driving because they cannot sustain alertness under the rigors of commercial transport operations. Conversely, there are low-susceptible individuals who are unlikely to be involved in fatigue- related incidents and crashes. Ideally, a diagnostic tool (e.g., a physiological or performance test) could be developed to efficiently and accurately assess a candidate driver’s level of fatigue susceptibility. Such a tool would not diminish the importance and value of improved fatigue management by drivers and fleets; rather, the combination of driver selection and alertness-supportive management techniques would combine to dramatically reduce drivers’ risks of attentional lapses and falling asleep at the wheel. An ultimate R&D goal relating to assessing fatigue sus- ceptibility would a test to identify a person’s chronotype, as defined and discussed in chapter two. There would also be benefit from having simple but validated questionnaire on driver sleep-related habits, history, and attitudes. Valida- tion would require correlation of questionnaire responses with driving outcomes using methodologies described in chapter three. Many enduring human qualities affect the ability or the choice to drive safely. Six categories of such traits and many specific examples have been provided. Nonetheless, safety- related traits are not necessarily immutable. They change with maturation, and safety management techniques like Behavior-Based Safety can change driver attitudes as they change behavior. Beyond the scope of this report are the many temporary driver states affecting safety, such as recent sleep and moods. On surveys, these were rated about the same as enduring traits as forces affecting safety. Research is needed on the consistency of safety-relevant driver traits and ways they may change. Change may be the result of maturation, environmental factors, or management prac- tices. Some characteristics may be more resistant to change than others, thus making them relatively more important for selection. Those amenable to change may be best addressed through supervisory practices. This report has not delved into theories of personality and attitudes, but rather emphasizes research findings with practical applications to driver selection. However, theoreti- cal research does have long-term practical benefits. Efforts to develop and apply instruments for selecting safe drivers would benefit from a better understanding of the structure of human personality and attitudes in relation to driving safety. The Theory of Planned Behavior is one framework to identify better predictors of safety behaviors and outcomes. These predictors could be measured by questionnaires assessing applicant personality traits, attitudes, perceptions of social norms, and perceived behavioral control. All of these personal attributes are relevant to safety. Surveys done for this synthesis provided useful infor- mation on the relative views of respondents on various driver risk factors and driver selection practices. How- ever, as emphasized, survey samples were convenience samples, not samples representative of larger populations. Development of more representative samples of motor car- rier safety managers or other populations of interest would require more information about those populations and bet- ter ways of reaching them. The CTBSSP and other motor carrier research programs would benefit from the develop- ment of this capability. More structured surveys would pro-

65 vide more information on the practices of the overall CMV transport industry. Chapters two and three described multiple studies relat- ing various human traits, and measurements from various psychological tests, to driving safety. Most of these studies were not conducted on commercial drivers, and few pro- vided all the validation evidence needed to justify legally and ethically the use of a test for hiring commercial driv- ers. More typically, they provided a rationale for resource- ful carriers to try out the tests and attempt to validate them for their own fleets. Smaller carriers and others without the resources for fleet-based research are not likely to be able to perform such validation experiments. Therefore, more com- mercial driver selection test validation studies are needed, with results made available to the industry. Carriers could replicate these studies in their own fleets to further ensure fair and legal hiring. Questionnaires and other instruments for driver hiring would need to be designed to prevent driver applicants from “gaming the system” by providing socially desirable answers. A barrier to more widespread and systematic use of selec- tion tests and measurements is the technical and legal knowl- edge necessary for carrier managers to implement such methods. Topics include statistical measures and concepts, testing principles, employment law, driver individual differ- ences, and crash risk analysis. The motor carrier industry needs educational offerings in these areas. This report has been written primarily from the car- rier management perspective, because driver selection is performed by managers. The driver perspective has been most evident in report discussions of test characteristics and requirements, such as test validity. To the extent that tests are valid, they are also fair to drivers, because they make an accu- rate selection recommendation based on driver traits linked to job performance. Nevertheless, drivers’ perspectives on selec- tion, other job assessments, and other carrier safety practices are important in their own right. Future safety studies might survey drivers directly or seek input from driver advocates such as union representatives with experience as drivers. Because of the exorbitant harm traceable to high-risk drivers, much of commercial driver selection is about “find- ing the bad.” Yet a positive model of the successful com- mercial driver—one who is competent, conscientious, agreeable, and manageable—also emerges from information gathered in this synthesis. These drivers may be asocial and autonomous, but they are not antisocial. More research into driver selection is needed to formalize and fully validate this positive driver model, and to provide information to carriers on how to use biodata, questionnaire inventories, and other assessments to select these drivers.

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TRB’s Commercial Truck and Bus Safety Synthesis Program (CTBSSP) Synthesis 21: Driver Selection Tests and Measurement synthesizes information on the use of tests, measurements, and other assessment methods used by commercial truck and bus companies in the driver selection process. The report also identifies and describes driver selection methods and instruments and their potential usefulness in predicting driver crash risk.

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