The American Trucking Associations on June 9 said an internationally recognized safety researcher has questioned the cache of studies submitted recently by the Federal Motor Carrier Safety Administration to support its hours-of-service proposal, saying the studies contain many problems and shouldn’t be relied on to support the agency’s proposed changes.

Ronald R. Knipling, former head of FMCSA’s research division and the first American to receive the Order of Merit from the International Road Transport Union for his work on truck safety, questioned the validity of the studies the agency inserted into the docket on May 6 after closing the comment period for its Notice of Proposed Rulemaking. FMCSA reopened the comment period for 30 days for discussion related only to the new documents; the deadline to submit comments was June 9.

Knipling raised “fundamental criticisms” of a study conducted by researchers at Pennsylvania State University, concluding that the sample of drivers, trucks and crashes, as well as minimal attention paid to other factors in crashes, rendered the study of little value. “It would be erroneous and unwarranted to accept Penn State’s principal findings and conclusions without extensive reanalysis, internal validation and external replication,” he wrote.

Similarly, Knipling said a study by the Virginia Tech Transportation Institute was lacking and concluded that “more probing and self-challenging analyses must be performed before [the] study[’s] findings can be accepted as sound science.”

Regarding a study of Florida transit bus drivers, Knipling concluded that the “significant differences between Florida’s transit bus operator work rules and those for interstate truck drivers render schedule-related research findings for one largely inapplicable to the other.”

Knipling also submitted a summary of his own work on the subject. He found that fatigue related to lack of prior sleep, being awake for more than 16 hours and early-morning driving was associated with many single vehicle truck crashes, while fatigue “related only to driving and work schedules (e.g., as prescribed by daily hours-of-service rules) were not. This non association was confirmed by several different types of analyses.” In addition, Knipling noted the risk of all types of truck crashes increased during daytime driving “consistent with increased exposure.”