A new study underscores earlier evidence that the greatest risk of an accident occurs in the first hour of driving, and that the risk in the second through 11th hour is relatively flat.

The study by Richard Hanowski, director of the Center for Truck and Bus Safety at the Virginia Tech Transportation Institute, found is that the risk of a critical driving incident is significantly higher in the first hour of driving than in all other driving hours - and that there is no statistical difference in risk between the 2nd through 11th hours.
This underscores the 1st-hour spike found by the Large Truck Crash Causation Study, which reported that the 1st hour had the highest raw percentage (14.7 percent) of crashes, Hanowski said.
Overall, however, the data on this issue is mixed. A 2005 study, for example, found that risk increases as driving hours accumulate, Hanowski noted.
Hanowski said his analysis, which was completed in January and is now in peer review, is based on the largest on-road naturalistic study ever conducted. It includes 2.3 million miles of driving data and 190,000 hours of sleep data from wrist actigraphs worn by the drivers in the study.
Watch for more in the print edition of Heavy Duty Trucking.