Effect of Visible Light Transmission from Vehicle Windows on Traffic Flow of Car-Following

Abstract

Regulation of the percentage of visible light transmission (VLT) has been controversial because the driving behavior of the following vehicle depends on the integrity of the vision field. It is conjectured that the level of VLT of a vehicle can affect the stability and headway of vehicles. Car-following theory can be a useful tool to analyze the effect of vehicle VLT on traffic flow in cases in which proper field data can be obtained. Most car-following experiments have been based mainly on mathematical analyses, which, because of a lack of accurate equipment, assumed that the response of the drivers was uniform. Now, global positioning systems (GPSs) and other advanced technologies make it possible to obtain vehicle trajectories and to monitor driving behavior accurately. This study focuses on identifying the effect of vehicle VLT on the local and asymptotic stability underlying car-following theory. Car-following experiments were performed for VLT of 70%, 30%, and 0% with a real-time kinematic GPS receiving apparatus. In addition, both local and asymptotic stability were analyzed to verify the relationship between VLT and the stability of vehicle trajectories. Driving behavior was also investigated with acceleration noise and distance headway. The VLT of tinted windows is found to have a statistically significant effect on the following driver's behavior. Further studies should focus on measuring the negative impact of lower VLT to establish minimum standards for VLT for various velocities and different types of vehicles by using this experimental method.