Michigan's Commercial Driver's License (CDL) Experience

The Commercial Motor Vehicle Safety Act (CMVSA) of 1986 established uniform federal standards for testing and licensing to ensure the “fitness” of persons who operate commercial motor vehicles. The purpose of the research reported on here was to determine if the results of such standardized testing could be directly linked to safer commercial vehicle operation in Michigan. The relationships between Commercial Driver License (CDL) test performance, driver demographics, driver attitudes, driver knowledge, and driver safety-related history were studied. These relationships were used to examine questions such as: are alternate forms of the CDL test equivalent; are there problems with testing bias; is the CDL test “good” at differentiating between drivers with safe or unsafe driving habits; can CDL test scores be related to driver safety; and, does the CDL test penalize drivers who have good driving records, but poor verbal skills? The analysis resulted in the identification of several negative aspects of the CDL test. First, the alternate forms of the CDL are not equivalent. Second, educational, racial, and, gender biases were identified in the CDL test structure. Finally, the CDL test structure may penalize drivers with “safe” driving records, but poor verbal skills. Several positive aspects were also identified. First, the CDL study manual is aiding drivers in meeting the minimum knowledge requirements for the operation of commercial vehicles. Most importantly, it appears that, on the whole, the CDL test is an effective tool for identifying safe drivers.