As the Federal Motor Carrier Safety Administration goes about rewriting its hours of service rules for truck drivers, it has been careful to make sure those changes are backed up by scientific studies. But it's starting to look like the regulators need to go back to science class.

As we went to press, the American Trucking Associations put out a news release announcing that a prominent researcher says the FMCSA misapplied the findings of a study he worked on.
FMCSA used the work of Dr. Francesco Cappuccio at Warwick Medical School in the United Kingdom, who reviewed 16 published studies on the effect of sleep duration on mortality. Cappuccio co-authored a 2007 study the agency used to conclude that short projected increases in sleep could generate roughly $690 million in annual health benefits for drivers.

In a new report, Cappuccio states the agency misused his sleep research, and concluded that FMCSA cannot use it to quantify benefits to justify its regulatory changes.

Cappuccio cautions in his report that the research "relies exclusively on observational epidemiological data and it is acknowledged that the evidence produced from such studies does not demonstrate or even imply a cause-effect relationship."

Inferring cause-and-effect from research that finds correlation can be in error. After all, there's probably a correlation between people carrying umbrellas and the likelihood of rain; does that mean carrying an umbrella causes the rain?

The current evidence, Cappuccio writes, does "not support the conclusions of the FMCSA that a small increase in sleep duration of a few minutes following the HOS options proposed, particularly in the groups with baseline daily sleep of more than six hours per night, is likely to decrease the mortality risk of individuals or groups."

Further, he states that there is "no evidence to prove that, without additional measures, a simple reduction in work hours will result in increased sleep time."

This is on top of criticisms by ATA and others in the industry of two studies used by FMCSA to justify changes in the 34-hour restart. The studies focused on a very small number of subjects, and those subjects were not truck drivers. (See "Washington Report" in this issue for more details.)

Don't even get me started about all the different "fatigue" studies that are all over the board. Estimates of fatigue as a factor in truck crashes range from 50 percent by the National Transportation Safety Board to 4.5 percent by the Large Truck Crash Causation Study.
Then there's the question of how the agency can possibly determine which of the many regulations it's been throwing the industry's way are actually responsible for future safety improvements.

If truck-related fatalities are cut by half in the next decade, it's great news. But how will we know if that was a result of new hours of service regulations, mandatory electronic onboard recorders to track those hours, the new CSA enforcement regime, texting and handheld cell phone bans, access to pre-employment screening, sleep apnea screening, a central drug-testing database, stricter driver health standards, or a non-regulatory item such as collision avoidance and lane departure warning technology?

A website for kids designing experiments for science fairs explains it clearly and simply: You conduct a fair test by making sure that you change only one factor at a time while keeping all other conditions the same.

The FMCSA is changing so many factors, so fast, it would flunk a science fair for sure.

From the March 2011 issue of Heavy Duty Trucking magazine.