Cell phone use while driving is dangerous. From 2010 to 2016, 9.5% of fatal crashes in the USA involved a distracted driver, and cellphone usage was one of the main distracting factors. Previous studies used crash data or safety-critical events to quantify the influence of cell phone use on driving safety. However, crash data have limited sample size and safety-critical events suffer from being sensitive to thresholds and driving situations. To address these two issues, we propose using the interaction of drivers in specific driving behaviors to quantify driving risks. Specifically, we used a safety assurance model called responsibility-sensitive safety (RSS) to quantify driving risk during drivers’ longitudinal interactions. The RSS model defines a safe longitudinal following distance based on vehicle acceleration, relative speed, and driver’s reaction time, and will classify a driving scenario as unsafe if the observed inter-vehicle distance is shorter than the safe distance. The impacts of cell phone use on the exposure and severity of longitudinal driving risk were investigated using car-following data from the Shanghai Naturalistic Driving Study (SH-NDS). The exposure measures the proportion of time in risk, and the severity represents the average risk severity during a car-following event. Cell phone use was classified into Browse, Conversation, Text, Hold in hand, and Change phone position. Environment and demographic characteristics were also considered as factors influencing longitudinal driving risk. A Tobit model was utilized to handle censored continuous data for specific phone use tasks and car-following conditions. Results show that while Conversation, Text, and Browse lead to more cautious driving behavior, Change phone position and Hold in hand lead to more driving risk exposure and severity than expected, especially on high speed roads. Results from this study can support legislation for cell phone restriction on high speed roads, and can help drawing more attention to the risk of distractions in driver training, education, and management.
Rongjiao Xu, Xuesong Wang*, Meixin Zhu. Impact of Cell Phone Use on Driving Risk: A Naturalistic Driving Study. Transportation Research Board 101th Annual Meeting, Washington D.C., USA, 2022. 1.9-13.