Distracted Driving Effects on Headways at Signalized Intersections

Distracted driving poses one of the most difficult challenges to ensuring a safe and efficient transportation system. Modern communications have delivered greater convenience. However, this has come at the cost of attention spans. Safety has been thoroughly explored from the perspective of distracted driving. However, impacts on traffic operations have received minimal research attention. A few studies have provided a theoretical mechanism on how intersection operations can be affected, but fail to quantify the real-life impacts on traffic operations. This research aims to quantify how distracted driving affects vehicle discharge headways at signalized intersections for through lanes. Thousands of observations were collected from four intersections in Orange County, Florida, covering a variety of land uses, intersection configurations, and periods of high demand. The results demonstrated that approximately a quarter of all drivers were distracted. Drivers were less distracted in commercial zones and more attentive to signal changes compared to school and residential areas. Cell phone usage had the primary effect on headways among distraction types with a 20% increase, which resulted in reducing the intersection capacity by 16.5%. The statistical model demonstrated that the overall effect of distraction on the discharge headway is significant. The base headway increased by 0.93 s, which resulted in reducing the intersection capacity by 45.5%. The results also revealed that the 10th vehicle position in the queue had a detrimental effect on the headway and the overall intersection capacity. The green phase gaps out because of the amount of time needed to reach the stop bar.