Study On The Reasonable Spacing Between The Grade Intersection And The Adjacent Access Of First-Class Highway

In recent years,with the rapid development of roads in urbanized areas of China,the construction mileage of roads has been gradually improved,and the national highway network has been upgraded and improved.However,there are still more problems in the planning and design of primary highways in the national highway network.Through relevant research and survey,it is found that,influenced by the traffic characteristics of urbanized areas,there are some unreasonable design problems of right-in and right-out access points on the level intersection sections of the collector-type primary roads.If the spacing between the intersection and adjacent entrances is not reasonable,it is easy to reduce the traffic efficiency of the primary highway and even cause traffic safety accidents.Therefore,in this thesis,with reference to relevant research results at home and abroad,combined with on-site traffic survey,theoretical research combined with simulation analysis is carried out to study the spacing between level intersections and adjacent upstream and downstream entrances of primary highways,and a reasonable spacing value between level intersections and adjacent entrances of primary highways is obtained.Firstly,the research scope of the spacing between primary road level intersections and adjacent entrances is determined by combining the relevant domestic and international codes and related researches,and the influence of road conditions,traffic conditions and other conditions on the spacing is analyzed.The traffic data such as road geometry characteristics and traffic flow operation characteristics of the road section between the level intersection and the adjacent entrance of the primary highway were obtained through on-site traffic survey,and certain differences in the vehicle operating speed of each lane under the same design speed were obtained.Using Tracker software to extract the traffic data of the investigated road section,such as vehicle left lane change and right lane change trajectory data,Matlab software was used to fit and analyze the vehicle lane change trajectory data,and the hyperbolic positive lane change trajectory model was determined as the vehicle lane change trajectory model in this study with the fit degree as the index.Secondly,the theoretical spacing model of the first-class highway intersection with adjacent upstream and downstream entrances with different design speeds and different number of lanes was constructed by fully considering the traffic flow operation characteristics of the first-class highway intersection and adjacent entrances,and solving the theoretical spacing model of the first-class highway intersection with adjacent upstream and downstream entrances with different design speeds and different number of lanes,based on the fact that each lane has different vehicle driving speeds under different design speeds.The recommended values of theoretical spacing between two-way six-lane and two-way four-lane primary highway level intersections and adjacent upstream and downstream entrances are solved under the design speed of 80km/h and 60km/h.Finally,according to the recommended theoretical spacing values of primary highway level intersections with different design speeds and lane numbers and adjacent upstream and downstream entrances,the maximum average traffic density and the speed difference between design speed and average speed at four levels of service are used as evaluation indexes,and the VISSIM simulation software is used to verify the reasonableness of the recommended theoretical spacing values,and the recommended spacing values of primary highway level intersections with different design speeds and lane numbers are derived.The recommended theoretical spacing between the primary road level intersection and the adjacent upstream and downstream entrances is reasonable and feasible.The conclusions of this study are of certain guidance and practical significance for the design of the spacing between the level intersections and adjacent entrances of primary roads in China.