Research Project

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Commercial Driver Individual Differences Study


To identify the most critical driver characteristics—such as medical or work histories—that increase crash risk.


The feasibility of collecting exposure-based risk data for selected characteristics, as well as the feasibility of identifying commercial motor vehicle (CMV) driver factors that contribute to increased risk of large truck crashes was explored. A follow-on pilot study was performed to determine the relative crash risk associated with driver characteristics, general health and wellness issues, medical conditions, drugs, and other driving performance characteristics. The next phase will be a full-scale study and will incorporate lessons learned from the pilot study.


The objective of the case-control Commercial Driver Individual Differences Study (CDIDS) is to examine a wide array of driver and situational factors to determine their prevalence in—and relationship to—being involved in a crash. The CDIDS will identify and prioritize commercial driver individual risk factors that primarily will consist of personal factors such as demographic characteristics, medical conditions, personal attitudes, and behavioral history. These factors will also include work environmental conditions, such as carrier operations type and compensation method. Risk factors will be identified by linking the characteristics of individual drivers with their driving records through the duration of the study. Of particular importance will be the occurrence or absence of critical incidents, including preventable crashes, crashes regardless of preventability, moving violations, and vehicle inspection violations. The study has the following goals: 

  • Determine whether individual factors such as demographic characteristics or medical conditions result in increased risk for a CMV crash or violation.
  • Determine if there is a relationship between fleet characteristics and protocols and CMV driver performance and health.
  • Identify contributing factors leading to a CMV crash.
  • Track carriers and CMV drivers for up to 3 years after an initial CMV driver survey for identification of additional crash data and validation of study results.


A report that identifies individual factors that increase crash risk.


September 2010     Project start
May 2013                   Information Collection Request Approved
September 2015      Project completion




The contractor is recruiting 20,000 drivers at six sites. In addition, the contractor regularly reviews fleet crash data and Motor Carrier Management Information System (MCMIS) data to identify participating drivers for case events. Once a case driver has been identified, he/she is contacted to complete a follow-up questionnaire along with four control drivers.


Virginia Technical Transportation Institute

Updated: Thursday, January 8, 2015
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