Human factors in vehicle collisions include anything related to drivers and other road users that may contribute to a collision. Examples include driver behavior, visual and auditory acuity, decision-making ability, and reaction speed.
A 1985 report based on British and American crash data found that driver error, intoxication, and other human factors contribute wholly or partially to about 93% of crashes.
Drivers distracted by mobile devices had nearly four times greater risk of crashing their cars than those who were not. Dialing a phone is the most dangerous distraction, increasing a driver’s chance of crashing by twelvefold, followed by reading or writing, which increase the risk by tenfold.
Motor Vehicle Speed
The U.S. Department of Transportation published its Federal Highway Administration review research on traffic speed in 1998. The summary says:
- The evidence shows the risk of having a crash is increased both for vehicles traveling slower than the average speed, and for those traveling above the average speed.
- The risk of being injured increases exponentially with speeds much faster than the median speed.
- The severity/lethality of a crash depends on the vehicle speed change at impact.
- There is limited evidence suggesting lower speed limits result in lower speeds on a system-wide basis.
- Most crashes related to speed involve speed too fast for the conditions.
- More research is needed to determine the effectiveness of traffic calming.
Driver impairment describes factors that prevent drivers from driving at their normal levels of skill. Common impairments include alcohol, drug use, physical impairment, old age, sleep deprivation, and other factors.
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