The Effects Of Supplementary Traffic Signs' Design And Presentation On Driving Behavior

Objective The study is to investigate the driver's processing of supplementary traffic signs at urban roads,analyze the problems of supplementary traffic signs' design and presentation and propose improved recommendations.Method This study consists of a pre-experiment and three formal experiments.The pre-experiment is aim to detect the ACC(accuracy)and RT(reaction time)of recognition when subjects responding to the picture of indication and prohibition signs,and provide the basis for selecting the materials of following experiments.The independent variables of Experiment 1 are the number of supplementary traffic signs' information(1,2,3)and its location(below,right).Experiment 2 is to investigate the difficulty when supplementary traffic signs appeared with different categories of main traffic signs(involve or not involve the information of direction)in the case of a different amount of information(1,2,3).Experiment 1 and Experiment 2 are cognitive behavioral experiments,Experiment 3 presents the information of supplementary traffic signs in auditory channel.There are two cases on the driving simulator(with or without voice),and the simulator record subjects' average speed,following distance and lateral offset.Results(1)Experiment 1 consists of Experiment 1a and 1b due to the different experimental materials.Experiment 1a: One piece of information,there is significant difference between the two locations of supplementary traffic signs(below < right);Two pieces of information,there is significant difference between them(below < right);Three pieces of information,there is significant difference between them(below > right).Experiment 1b: One piece of information,there is no significant difference between the two locations of supplementary traffic signs.Two pieces of information,there is significant difference between them(below < right);Three pieces of information,there is significant difference between them(below > right).(2)Experiment 2 consists of Experiment 2a and 2b due to the different experimental material.Experiment 2a: There is no significant difference between directional and non directional signs.Experiment 2b: There is no significant difference between directional and non directional signs when the number of information is 1 or 3.There is significant difference between directional and non directional signs when the number of information is 2.The reaction time is longer when supplementary traffic signs appeared with directional prohibition signs.(3)There are significant differences between two conditions(voice and no voice).Average speed: no voice < voice;Following distance: no voice > voice;Lateral offset: no voice > voice.Conclusions(1)When the number of supplementary traffic signs' information is one or two,it is reasonable to be placed below the main traffic signs.When the amount of supplementary traffic signs' information is three,it is more reasonable to be put on the right side of the main traffic signs.(2)The prohibition signs can be divided into the directional and non directional signs.It is harder for drivers to cognize when the supplementary traffic signs are appeared with the directional traffic signs.(3)The information of supplementary traffic signs presented in auditory channel is better for driving behaviors than presented in visual channel.It will improve driving performance,ease traffic congestion and reduce traffic accidents when the information of supplementary traffic signs are presented in auditory channel.