What demographic and contextual factors predict drivers’ turn signal usage at junctions?

Using naturalistic driving data, this study determined the predictors of turn signal use (for both right and left turns) by drivers as they pass through junctions and investigated the likely impact of secondary task involvement on such utilization. In-vehicle video recordings and recordings of external scenes were coded for turn signal use, defined categories of secondary behaviors and associated contextual factors. The findings revealed that when drivers were distracted by the secondary tasks, they signaled turns less frequently than while driving under typical baseline conditions. The rates of signaling decreased more dramatically with the increasing complexity of secondary tasks. Lastly, drivers used turn signals more frequently in urban areas than in rural areas, at junctions without a dedicated turning lane than those with such passage, when turning left opposed to right, and at non-roundabout junctions than at roundabouts. In conclusion, drivers have a higher inclination to utilize turn signals when faced with demanding or challenging driving situations. The findings pave the way for the development of effective measures for increasing turn signal usage, which is an important safety behavior.