Research On The Minimum Spacing Of Interchanges On Intercity Highway

Since our country is in the rapid development stage of the city at present,the scale of the city expands rapidly,the theory of regional development and the practice of construction continue to improve,and the traffic links between cities continue to be strengthened.As a result,there is a need for highway construction that should take into account the function of urban roads in these areas with high rate of cities(towns)development and high-speed development of cities(towns).It thus has added some city service functions on the basis of the traditional highway traffic function,which makes the intercity highway come into being.As for the intercity highway,it refers to a highway with a certain urban service function that is connected to a city at or above the county level in the urban planning area or the planning impact area.There is no doubt that the density of the road network increases in the process of urban development,so there are more roads crossing with each other.While the interchange is an important means of traffic transfer and traffic distribution on the intercity highway,which is spread over the urban planning area or the planning impact area.Thus,it is necessary to set reasonable distance between adjacent interchanges in the process of design and construction of intercity highway,so as to ensure the stability of intercity highway traffic flow and the economic development of surrounding areas.In this paper,it firstly makes the definition of the spacing of interchanges on intercity highway,which then analyzes the main influencing factors of the distance between adjacent interchanges with independent and auxiliary lanes.In addition,it measures the model values of the structure length and ramp length of the interchange after drawing out different forms of interchange model diagram.It obtains the statistical values of interchange structure length and ramp length after making statistical analysis of different forms of intercity highway interchange data.And it determines the recommended values of intercity highway interchange structure length and ramp length after comparing model values and statistical values.Secondly,it analyzes the vehicle change behavior of the adjacent interchange of intercity highway under the most unfavorable driving behavior on the basis of the traffic flow theory,which thus sets up the minimum spacing model of independent adjacent interchange of intercity highway.It determines the minimum spacing of the independent adjacent intercity interchange with different design speed,the number of lanes and the form of intercity interchange in combination with the recommended value of the structure length of the intercity interchange.Thirdly,it analyzes the influencing factors of traffic conflict for the adjacent interchange with auxiliary lane on the intercity highway.And it uses the VISSIM simulation software to design the experiment.Then,it draws the graph of the relationship between the number of traffic conflicts in the interleaving area and the three variables such as the equivalent traffic volume,the length of interleaving area and the ratio of interleaving flow.Thus,it establishes a traffic conflict prediction model of adjacent interchanges for intercity highway with auxiliary lane setting under different design speeds.Finally,it selects the conflict rate as the evaluation index of traffic safety in the interleaving area through the index reliability analysis.It determines the minimum spacing between adjacent interchange on intercity highways with auxiliary lanes in combination with the traffic conflict prediction model and ramp length in the interleaving area,which also makes the test by example.It can be seen that the study in this paper provides new theory and reference for solving the setting of the spacing of interchanges on intercity highway and the minimum spacing of interchanges in The Standard for Intercity Highway Design,which thus has certain practical significance.