Investigating Lane Change Behaviors and Difficulties for Senior Drivers Using the SHRP 2 Naturalistic Database

Older drivers are more likely to be involved in a lane change crash compared with middle-aged drivers. While a number of different blind spot warning systems and intervention systems exist, a more thorough understanding of in situ lane change behaviors and difficulties for older drivers may be beneficial to inform future lane-change support systems and the development or improvement of related training modules. This effort examined lane-change behavior and glance locations for three age groups, younger (18–29 years), middle-aged (30–49 years), and older drivers (70–94 years), using data from the Second Strategic Highway Research Program (SHRP 2) Naturalistic Driving Study (NDS). Descriptive outcomes were reported for several glance characteristics, including glance duration and percentage of time, as well as entropy as a measure of glance dispersion. Various behaviors, including turn signal use, glance errors, and environmental characteristics, were analyzed. For both uninterrupted and interrupted lane changes, results showed that many drivers, regardless of age, failed to make over-the-shoulder (OTS) and side mirror glances prior to initiating the lane change. Most drivers relied on side mirror and rearview mirror checks for lane change safety. Many drivers failed to check the side mirror prior to initiating the lane change maneuver. In addition, many drivers failed to activate the turn signal prior to lane change initiation, and only approximately 60% of older drivers activated the signal at any point during the lane change. For uninterrupted lane changes, when a conflict did occur with relation to the lane change maneuver, it was most frequently associated with either a lead vehicle in or a lead vehicle incurring into the destination lane. Results for interrupted lane changes showed that when a conflict did occur with relation to the lane change maneuver, it was most frequently associated with two sources of conflict: lead vehicle in or incurring into the destination lane or a trailing vehicle in or incurring into the destination lane. Left lane changes also showed a moderate level of conflict with adjacent vehicles in or incurring into the destination lane. Nearly one-third of interrupted lane change maneuvers involved an event where the participant proceeded despite improper spacing and cut off a trailing vehicle in the destination lane. As driver age increases, the percentage of events where the driver cut off another vehicle increases: while younger drivers cut off another vehicle 19% of the time, middle-aged drivers did so 27% of the time, and older drivers 28% of the time.