Studying the tailgating issue in rhode island and its treatment

A human factors study was conducted to investigate the tailgating issue in Rhode Island and possible means for tailgating treatment. Tailgating is an aggressive driving behavior with a deadly consequence. Following a vehicle too close, i.e., with less than two seconds of following distance, is considered tailgating on Rhode Island highways. To mitigate rear-end collisions caused by tailgating, this study aimed to find out causes of tailgating and public's opinions on tailgating issue as well as to identify possible tailgating treatments. Consisting of a vehicle headway analysis and a questionnaire survey, this study first assessed the tailgating situation on major Rhode Island highways. Surveillance videos capturing 8-lane traffic on three test sites of I-95, I-195, and I-295 in Rhode Island were taken during both rush hours and non-rush hours each day in a two-week period during December 2008. Based on the time stamp embedded in videos, vehicle headways were collected by calculating the intervals between two consecutive vehicles on the same lane passing a fixed reference point. Vehicle headways were tabulated in increments of seconds by day of the week, time of the day, and test site. The results identified serious tailgating situation on Rhode Island highways. More than 60% of vehicles were following with less than 2 seconds of headways during rush hours while 38% were tailgating during non-rush hours. It further found that vehicles on the high speed (innermost) lane exhibited the worst tailgating behavior, especially during rush hours. With serious tailgating issue confirmed, a two-phase questionnaire survey was developed to help find the causes of tailgating and to identify drivers’ responses to proposed tailgating treatments. The first phase was designed to identify the causes and effects of tailgating, and to gain insights about drivers’ understanding and interpretation of tailgating behavior. Nineteen questions presented in PowerPoint slides were shown to 210 subjects participated in this phase to capture their perceptions on various tailgating issues. The second phase was developed to gather drivers' preferences regarding several proposed tailgating treatment systems. These systems, consisting of pavement marking, roadside marking, dynamic message sign, and fixed road sign were presented to 142 subjects in simulated driving videos in six questions. The questions were presented in a sequential manner and the choices shown in a question would depend on the answer chosen in the previous question. Survey results obtained from the first phase found that the majority of drivers did not know what the proper vehicle headway was to keep while following other vehicles on highways. Most of them considered tailgating a serious offense and one of the top three major causes of highway crashes, however, most of them still maintained insufficient vehicle headways while driving on highways. This finding further confirmed the observations made in the vehicle headway analysis, that is, most drivers on Rhode Island highways maintained insufficient vehicle headways. From the second phase of the survey, it found that the majority preferred horizontal bars painted on pavement as a means to help maintain safe following distance. Drivers would be advised to keep two bars visible from the vehicle ahead. Coupled with the pavement marking, most of them preferred to have the overhead graphic-aided dynamic message signs as a way to communicate to drivers about safe following distance. Based on the results of this study, recommendations to Rhode Island traffic management authorities were made. The findings of this study could contribute to the development of a standard tailgating treatment system to be included in MUTCD and help facilitate a more efficient and safer driving on US highway.