Research On Driving Load In Small Spacing Section From Interchange To Mountain Expressway Tunnel

With the rapid development of expressways in mountainous areas in China,due to the coupling of objective factors such as topography,geological conditions,road network planning and economic level,the clear distance between expressways in mountainous areas and tunnel entrances is generally compressed in spatial distance.After the driver accelerates from the ramp into the main line,he continues to decelerate into the tunnel entrance,which has certain safety hazards.In recent years,the accident rate of expressways in mountainous areas to tunnel sections has shown an increasing trend.Therefore,through the combination of real vehicle test and simulation test,this thesis intends to comprehensively select eye movement parameters and vehicle operation parameters,explore the visual characteristics and vehicle operation characteristics of drivers in small clear distance sections,judge the driving load of drivers in small clear distance sections,and propose and verify the corresponding traffic organization optimization scheme.Firstly,the scene is divided into ramp section,confluence section and clear distance section.Combined with the methods of literature review and field investigation,the influencing factors of traffic safety from mountainous expressway to tunnel small clear distance section are systematically analyzed from the perspectives of road traffic characteristics,traffic conflict characteristics in confluence area,driver ’s visual characteristics and light environment characteristics.A small clear distance section from the typical interchange to the tunnel in the mountainous city of Chongqing was selected as the real vehicle test site,including 4 small clear distance(ramp)sections,5 ordinary clear distance(ramp)sections and 2 small clear distance(main line)sections.Under natural driving conditions,eye movement data and vehicle operation data of 10 drivers were collected and processed.Secondly,the study found that the driver ’s fixation time distribution showed a lognormal distribution,and analyzed and compared the change characteristics of the driver ’s fixation behavior and saccade behavior related parameter indicators in different driving stages under different clear distance scenarios.It was found that the driver ’s fixation duration,fixation angle distribution,saccade amplitude and speed in the small clear distance scene were significantly different from those in the other scenes;at the same time,the K-means clustering algorithm is used to divide the driver ’s gaze area in the interchange to the tunnel section,and the Markov chain is used to quantitatively analyze the driver ’s gaze transition behavior,and the driver ’s one-step gaze transition probability and gaze steady-state distribution in different driving stages of different clear distance scenes are obtained.Then,the pupil area change rate and the instantaneous pupil area frequency weighted speed of the driver are selected to analyze and compare the variation characteristics of the pupil-related parameters of the driver in different driving stages of different clear distance scenes.Using the entropy weight TOPSIS method,eight important indicators of the driver’s gaze behavior,saccade behavior and pupil parameters are selected to evaluate and analyze the visual load of a total of 33 different clear distance scenes in different driving stages.Subsequently,the speed and acceleration are selected as typical vehicle operation parameters to analyze the driving operation characteristics of the interval section,and then the visual load index and driving operation index are selected.The rank sum ratio method is used to construct the driving load model of the small spacing section,and the driving safety threshold of the small spacing section is determined to be 0.531.Finally,the most typical small spacing section(Yangdu Interchange to Pujiachang Tunnel)is selected.Combined with the actual engineering situation,the simulation model is built by UC-win / Road,and the scheme design of traffic organization optimization under small spacing section is proposed and verified.