The purpose of this study was to investigate variables that are related to seatbelt use decision making process (i.e., whether and when to use the seatbelts) for teen drivers when compared to adult drivers, by using naturalistic driving data).
Shan Bao, PhD
Assistant Research Scientist
University of Michigan Transportation Research Institute
2012 - 2013
To achieve the objectives of this study, two unique naturalistic driving datasets will be used: one is the parent Integrated Vehicle Based Safety System (IVBSS) project (Sayer et al., 2011) and the other is the Teen-IVBSS project. In the parent IVBSS project which was funded by US Department of Transportation, a total of 108 randomly sampled, passenger-car drivers participated, with the sample being stratified by age (younger between 20 and 30, middle-aged between 40 and 50; older between 60 to 70) and gender (male and female). Sixteen late-model Honda Accords were used as research vehicles. Consenting drivers used the test vehicles in an unsupervised manner, simply pursuing their normal trip-taking behavior over a 40-day period, using the equipped vehicles as a substitute for their own personal vehicles. The Teen-IVBSS project was jointly funded from the Insurance Institute for Highway Safety (IIHS) and the Honda R&D North America (Buonarosa, Bao, & Sayer, 2013). A total of 40 teen drivers with equal number of male and female drivers (16 years and 6 months to 16 years and 9 months of age, with Michigan Level 2 Intermediate driving license) participated. Twelve of the original IVBSS research vehicles were utilized. The forty participants were balanced for gender. Each teenager drove an instrumented vehicle for a 14-week period. Both projects were conducted by the University of Michigan Transportation Research Institute’s (UMTRI) while the parent IVBSS data was collected between April 2009 and April 2010 and the Teen-IVBSS data was collected between July 2011 and September 2012. Data on whether drivers put on the seat-belts during each trip was extracted and compared across different variables. Each trip was defined as a vehicle operation cycle which begins with engine start-up and ends with engine shut-off. Seatbelt use was determined via a signal from the vehicles Car Area Network (CAN) bus. The second dependent variable is when drivers used their seatbelts during a trip. The segment of the trip during which drivers first fasten their seatbelts relative to trip duration during all the belted trips were timed and compared. For the purpose of analysis, trip segment of seatbelt use was categorized into two stages based on trip elapsed time at the time point when drivers first put on their seatbelts: early-stage (i.e., driver put on their seatbelts within five seconds of trip start); and late-stage (i.e., drivers put on their seatbelts after five seconds). The 5-second filter was used because seatbelt reminder warnings were all first issued within this time period. The independent variables examined in this study include age (teen, younger, middle-aged or older), gender (male or female), time of a day (day or night), wiper state (on or off), average driving speed during each trip (continuous variable), and trip distance (continuous variable). The data were analyzed using logistic regression models in SAS. 9.2. Results found significant differences on the likelihood of seatbelt use between teen drivers and each of the three other age groups. In 2012, MAP-21, the Moving Ahead for Progress in the 21st Century Act (P.L. 112-141), was signed into law by President Obama on July 6, 2012. MAP-21, Sec. 31202 (Permits Reminder System for Non-use of Safety Belts) allows NHTSA to remove the limit on the duration of the audible component of a seat belt reminder system and allows NHTSA to permit compliance with an FMVSS through a regulatory alternative that includes seat belt interlocks.MAP-21 is a milestone for the U.S. economy and the Nation’s surface transportation program. By transforming the policy and programmatic framework for investments to guide the system’s growth and development, MAP-21 creates a streamlined and performance-based surface transportation program and builds on many of the highway, transit, bike, and pedestrian programs and policies established in 1991. Therefore, how to increase seat belt use and to design effective systems is becoming an important and urgent task for NHTSA. This pilot study was designed to address the very important question of understanding drivers’ decision making in seat belt use. Findings of this pilot study will feed more research projects in how to design effective systems.
Assistant Research Scientist