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Driver FatigueA 100-car “naturalistic” driving study conducted by the Virginia Tech Transportation Institute (VTTI) says that fatigue is a cause of 20% of car crashes, rather than the 2%-3% previously estimated based on surveys, simulator studies and test tracks.

Plus, the study found, 18- to 20-year-olds account for significantly more fatigue-related crashes than any other age group. Adolescents’ sleep patterns shift to later hours; however, the school day still tends to start early, resulting in daytime sleepiness.

Older drivers can face similar issues with late nights and early work times, but have more experience coping with moderate fatigue – although, not always, the researchers say.

One-hundred drivers who commute into or out of the Northern Virginia/Washington, D.C., metropolitan area were initially recruited as primary drivers to have their vehicles instrumented or receive a leased vehicle instrumented for the study. Since other family members and friends would occasionally drive the instrumented vehicles, data were collected on 132 additional drivers.

Researchers selected a larger sample of drivers below the age of 25, compared with the total population of drivers, and a sample that drove more than the average number of miles.

The data acquisition system used for the 100-Car Study was developed by engineers at the VTTI. Sensors included five video channels, forward and rearward Vorad radar units, accelerometers, lane-tracking software, and an in-vehicle network sensor. The cameras were mounted unobtrusively in order to facilitate naturalistic driving behavior.

Researchers viewed more than 110,000 events in order to validate 10,548 events – specifically, 82 crashes, including 13 where the data was incomplete; 761 near crashes; 8,295 incidents, such as braking hard for slowing or stopped traffic; and 1,423 non-conflict events, such as running a stop light with no traffic present.

In addition, 20,000 randomly selected 6-second segments of video were viewed. Incidents of moderate to severe driver fatigue were noted, providing an estimate of the amount of time drivers were fatigued but were not involved in a crash or near-crash.

The total number of subjects who were involved in fatigue-related crashes and near-crashes was 38, with 11 drivers accounting for 58 percent of all the fatigue-related crashes and near-crashes.

Analyses with the 100-car study database will continue, plus data from a new U.S. study, the Strategic Highway Research Program, with 2,000 cars, will provide greater statistical power.

The 100-Car Naturalistic Driving data set was collected in 2003 and 2004 and has been mined numerous times since. Databases from the 100-Car study are available for public use on the Virginia Tech Transportation Institute website. Several publications resulting from analysis of the data are reported by the National Highway Traffic Safety Administration.

Source: Virginia Tech Transportation Institute