Browse Publications Technical Papers 2012-01-0261

Turn Signal Usage Rate Results: A Comprehensive Field Study of 12,000 Observed Turning Vehicles 2012-01-0261

The turn signal is a vital safety feature that is not only required to be built in as standard equipment on all vehicles, but their use by the driver in everyday driving is required by law. Since not all drivers are diligent at properly actuating turn signals in every situation, the use of the turn signal is less than 100%. However, despite the fact that turn signals are a crash prevention feature, no known study relating to turn signal usage rates is available from the National Highway Traffic Safety Administration, nor from the Department of Transportation, nor from any University, nor from other private safety organizations.
This paper summarizes a first-ever published comprehensive study related to turn signal usage rates by everyday drivers and summarizes it in a simple, yet highly accurate naturalistic observation format with the following basic premise: A vehicle is observed to be turning in a situation that is deemed by the observer to require a turn signal: was the turn signal "on" or was it "off" in that observed vehicle? The summary of the cumulated data of turn signal usage is expressed in terms of a percentage usage rate. All turning drivers are unaware that their visible actions are data points in a study so the results are extremely accurate. Both turns as well as lane change usage rates are studied. Crash rates resulting from neglected turn signals are discussed, revealing that this neglect causes more crashes than distracted driving. The present turn signal system that relies solely on driver input can only be described as "defective". The paper also discusses how patented Electronic Intelligent Turn Signals with Turn Signal Assist would vastly improve usage rates and therefore significantly lower crash rates for no added vehicle cost.


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