Driving After Dark

| May 28, 2001

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.

A professional driver survives because he has developed and constantly refines his situational awareness. As night falls, this awareness must include the new variables that decreased visibility and increased fatigue help to create. Drivers are notoriously bad at evaluating their fitness for duty, which means that many drivers are fatigued enough to impair their driving skills long before they are willing to admit it. It is also quite common to find the pro outdriving his headlights without realizing it.

Today’s headlights on low beam provide a lighted range of between 300 and 350 feet, high beams about 500 feet. On long stretches of rural interstate, it is easy to ratchet up speed and forget that stopping distances can begin to outpace visibility. Headlights illuminate much less of the world one sees through the windshield than does the sun. Peripheral vision is at an absolute minimum at night, allowing the stray deer to become a potentially lethal, if nearly invisible, hazard. In urban areas, the constant glare of headlights from oncoming traffic adds frustration and eyestrain to an already toxic mix of negative inputs.

Headlights, mirrors and windows obscured by dirt, rain, snow and ice further reduce visibility. It has, until recently, been difficult to keep headlights and windshields clean on a constant basis. Cleaning them at fuel stops is a necessity, but the effect of this effort is quickly lost in bad weather. Two new products from Trim Systems, formerly Commercial Vehicle Systems, help keep visibility at optimal levels on a constant basis.

Lightwatch is a headlight washing system available on some new model tractors as well as from dealers as an aftermarket product. Lightwatch literature says that its washer will remove even ice from headlights, a godsend to drivers whose only method of keeping lights clean has been to stop and clean them by hand. Clearview is a heated windshield cleaning and deicing system engineered to work with existing washer systems. It heats washing fluid to a preset temperature and applies it to the windshield in 10-to-40 second intervals unless it is turned off by the driver. For more information, Trim Systems at (800) 441-2048.

Even more common than weather as a culprit in reducing visibility is glare. And while fleet drivers may not be in the market for aftermarket add-ons to their trucks, they can reduce glare by purchasing a pair of yellow tinted sunglasses. This product is used by drivers on the ice roads of Canada’s Far North to cut the glare of sun on snow, and it is just as useful for highway night driving in the comparatively balmy conditions in the Lower 48. All of these products can be useful.

Driving After Dark

| May 28, 2001

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.

A professional driver survives because he has developed and constantly refines his situational awareness. As night falls, this awareness must include the new variables that decreased visibility and increased fatigue help to create. Drivers are notoriously bad at evaluating their fitness for duty, which means that many drivers are fatigued enough to impair their driving skills long before they are willing to admit it. It is also quite common to find the pro outdriving his headlights without realizing it.

Today’s headlights on low beam provide a lighted range of between 300 and 350 feet, high beams about 500 feet. On long stretches of rural interstate, it is easy to ratchet up speed and forget that stopping distances can begin to outpace visibility. Headlights illuminate much less of the world one sees through the windshield than does the sun. Peripheral vision is at an absolute minimum at night, allowing the stray deer to become a potentially lethal, if nearly invisible, hazard. In urban areas, the constant glare of headlights from oncoming traffic adds frustration and eyestrain to an already toxic mix of negative inputs.

Headlights, mirrors and windows obscured by dirt, rain, snow and ice further reduce visibility. It has, until recently, been difficult to keep headlights and windshields clean on a constant basis. Cleaning them at fuel stops is a necessity, but the effect of this effort is quickly lost in bad weather. Two new products from Trim Systems, formerly Commercial Vehicle Systems, help keep visibility at optimal levels on a constant basis.

Lightwatch is a headlight washing system available on some new model tractors as well as from dealers as an aftermarket product. Lightwatch literature says that its washer will remove even ice from headlights, a godsend to drivers whose only method of keeping lights clean has been to stop and clean them by hand. Clearview is a heated windshield cleaning and deicing system engineered to work with existing washer systems. It heats washing fluid to a preset temperature and applies it to the windshield in 10-to-40 second intervals unless it is turned off by the driver. For more information, Trim Systems at (800) 441-2048.

Even more common than weather as a culprit in reducing visibility is glare. And while fleet drivers may not be in the market for aftermarket add-ons to their trucks, they can reduce glare by purchasing a pair of yellow tinted sunglasses. This product is used by drivers on the ice roads of Canada’s Far North to cut the glare of sun on snow, and it is just as useful for highway night driving in the comparatively balmy conditions in the Lower 48. All of these products can be useful.

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