SAE observed a total of 12,000 lane-changing and turning vehicles and concluded 25 percent of drivers neglected to signal when turning and a whopping 48 percent neglected to do so when changing lanes. Applying these percentages to U.S. drivers as a whole translates to 750 billion instances of turn signal neglect per year – or more than 2 billion instances per day, according to the study.
The study estimated that approximately 2 million crashes per year are a direct result of this issue.
By comparison, the U.S. Department of Transportation estimates that about 950,000 crashes are the direct result of distracted driving (driving while texting, talking on the phone, eating, putting on makeup, etc.).
"This is a first-of-its-kind report on a subject that amazingly, has never been studied," said Richard Ponziana, president of RLP Engineering and author of the report. "The turn signal is one of the very original automotive crash prevention devices and this simple driver-to-driver communication device remains extremely effective, but only when it is accurately displayed as required by law."
"The turn signal can no longer be considered 'optional' and all drivers have an ongoing duty to use it, just as they have a duty to stop at a stop sign or at a red light."
SAE proposed a "simple" solution in the report: The Smart Turn Signal. This system uses vehicle sensors and computer control to assist the driver in assuring that the turn signal is used regularly – in other words, it tells you when you forgot to do so – and also shuts this signal off if the driver forgets that it is on.
According to SAE, because the system uses the same sensors employed by a vehicle's stability control system (which is standard on all new cars), adding Smart Turn Signals would come at no cost to the manufacturer or, in turn, the consumer.
The report also notes that Smart Turn Signals save weight and space, as they eliminate the turn signal trip mechanism – a system that has been around since 1940 and has never really been improved upon, despite exposed defects.
"Smart Turn Signals are the perfect complement to the Stability Control System since Stability Control predominately prevents single-vehicle crashes, whereas the Smart Turn Signal prevents multi-vehicle crashes," Ponziani said.
But until Smart Turn Signals are mandated on vehicles, keep in mind that while we're all guilty of turn signal neglect – I myself am a chronic offender – the numbers don't lie. Make a serious effort to use your turn signal whenever you're switching lanes or turning (and switch it off when you're done!) and help make the road a safer place.
For more information on the study, see the full report at http://www.sae.org.