21 Feb 2016


Of all forms of distracted driving, drowsiness is becoming increasingly recognised as a major cause of serious road traffic accidents, particularly as long journeys at unsociable hours grow more common in both the private and commercial vehicle sectors. Surveys by the US National Sleep Foundation show that private motorists who admit having ever driven while feeling drowsy account for half of all American adults, while 20% had actually fallen asleep at the wheel during the previous year. But it is commercial vehicle drivers that are most at risk.

The US National Highway Traffic Safety Administration conservatively estimates that 100,000 police-reported crashes each year are caused primarily by drowsy driving and result in more than 1,550 deaths, 71,000 injuries and US$12.5bn in economic costs.

Estimates have to be conservative since, as the Foundation points out, “Currently, there is no definitive physiologic test or detection system for drowsiness equivalent to the breath analysers used to detect drunk-driving.”

These analysers can also prevent drunk-driving at the outset by triggering ignition locks. But in the current absence of equivalent devices, police can have difficulty in conclusively identifying drowsiness as a crash factor.

At-the-scene indicators are restricted to factors such as the typical involvement of single vehicles with lone drivers (who tend to be fatally or seriously injured); and the lack of evidence, such as skid marks, of any pre-crash avoiding manoeuvres.

In the quest for technological solutions, researchers in Wuhan, China, have proposed a driver assistant system that would react specifically to the sharp rises in lateral acceleration and yaw rate acceleration that typically occur when those at the wheel have not had enough sleep. The project recruited 50 volunteers to test a vehicle equipped with sensors to monitor its movements in scenarios involving driver drowsiness and intoxication, as well as distractions such as talking and watching the roadside instead of looking ahead.

In the US, technologies being developed include Delphi Automotive’s video-based Driver State Monitor, which senses when a driver is blinking or nodding off to sleep and sounds an alarm if necessary. The system - initially designed for use in passenger cars, with commercial vehicles coming later - is due to reach the US market in 2016.

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