In the trucking business, neither management nor labor always knows ahead of time when a load will need to be moved. Pick-up and delivery times are made based on the needs of customers.
While management tries to coordinate its customers’ needs with the requirements of the law and the physiological requirements of drivers, delivery schedules do not and cannot take into account the fact that the night is made for sleeping.
Sleep scientists tell us that our biological cycles of activity are regulated by circadian rhythms. These rhythms of relative wakefulness are generated by an internal clock that is coordinated to lightdark cycles. As night falls, a hormone called melatonin is released into our brains. This hormone induces sleep. Yet, while there are other periods of low biological activity, particularly mid-afternoon, our minds and bodies are naturally geared to sleep when the sun goes down.
Dr. Richard Grace, of Carnegie Mellon’s National Robotics Laboratory, says, “This need for sleep is particularly strong between 2 and 6 o’clock in the morning. Drivers who constantly drive at night can become sleep deprived even though they may not exhibit sleep-deprived-performance problems. But these same drivers also lose the ability to perform at a high level.” The freight, nevertheless, must move.It is, therefore, fortunate that truck driving requires a constant low level of mental activity rather than an extremely high degree. The decisions a driver makes are often small, though significant. Adjustments to steering, the tiny muscular movements which keep a truck centered in its lane, are examples. Every steering adjustment is a decision. Glancing in the mirrors is a decision. Even pulling the eyes back to the windshield from the mirrors is a decision. When the melatonin is flowing and visibility is lessened by darkness, two strong negatives affect a driver. While he may be able to safely continue making low-level decisions, his reflexes may be slowed at exactly the moment when it is necessary to make instant and accurate decisions of the most significant kind.
In a report entitled, “Fatalities and Injuries in Truck Crashes by Time of Day,” prepared by Daniel Blower and Kenneth Campbell at the Center for National Truck Statistics for the Office of Motor Carriers, the authors note that, “Using exposure data classifying night as between 9 p.m. and 6 a.m. truck travel during that period is associated with a relative risk about twice that of the rest of the day.” Crashes at night are also more severe. According to the report, there are about three times as many fatalities per thousand crashes between midnight and 6 a.m.
The report says that fatigue is indeed a significant factor in single vehicle fatal crashes involving trucks. In other words, drivers fall asleep and run off the road more at night than during the day. But the risks do not come only from the drivers of trucks. “Almost 40 percent of the nontruck drivers in multiple vehicle crashes with trucks between midnight and 3 a.m. had used alcohol, compared with 2.7 percent of the truck drivers.
Fatigue also was coded more often for nontruck drivers than for truck drivers in multiple vehicle crashes.” The professional driver who is required to maintain delivery schedules around the clock is fighting not only his fatigue and his reduced sight distances, but also he is fighting factors, like alcohol consumption in the nonprofessional highway population. Perhaps a night driver’s only saving grace is the relative lack of nightly traffic.
