Design And Optimization Of Traffic Organization In New Interchange Construction Area Of Expressway

Over the past 30 years since the opening up,China has made all-round progress in its economic and social development,and its comprehensive national strength has unprecedentedly improved.As the basic industry of the national economy,expressway construction is developing fast and expressway traffic is of increasing demand.The present national road networks have been completed and put into operation,however,the road grade and traffic capacity can hardly meet the needs of the ever-increasing traffic logistics.During the period of the Tenth Five-Year and the Eleventh Five-Year Plan,our national "7918 Project of Expressway" has been basically completed.Meanwhile,expressway network in Jiangsu province has achieved "four vertical ? four horizontal and four connected".With the accomplishment of the main backbone of the transport network,motorways running through each city and county is becoming possible.To resolve the problem that several cities and counties cannot be included in the skeleton of the main road network because of their geography,topography and landform,which can only be covered by expressway through the construction of branch lines,in 2009,Jiangsu province propounded the "12th Five-Year Plan of Expressway Network",namely the accomplishment of a planning program of 5200 kilometers achieving "four vertical?nine horizontal and four connected" by the end of 2015.It follows that the connection between branch lines and the framework of the main roads is a critical way to further expand the coverage of road network and enhance logistics and the serviceability of transportation.The expressway is the only type of public facility that can provide complete uninterrupted traffic flow,of which the interchange is an important node.The construction of branch lines will inevitably be connected with the main skeleton of road network.Interchange construction is a necessary step forming road network for new and existing expressway.Therefore,it will be an important job to select the lapping type of the expressway,which will affect the normal traffic of the existing ones.During the process,due to the significant decline of traffic serviceability,vehicles have to take a speed reduction or an early shunt to bypass.While the traffic flow of the construction section increases instantaneously,the vehicle will inevitably become congested,taking a new road.On the new roads,the diverting,confluence and interweaving of vehicles often cause traffic disorder?violent speed changes?significant increase in the probability of traffic conflict as well as operation quality degradation,making the construction section a major location of expressway accidents.Vehicles may encounter falling objects,especially during the superstructure construction of bridges crossing lines,and be disabled from carrying on a new road by high speed in night passage.In case of bad weather,traffic congestion is easily caused by poor traffic in construction sections,bringing potential danger.As a traffic transfer node,interchange construction,which is connected to the main line by the way of lower or upper span,is an important part of the expressway.In the process of interchange construction,whatever type is adopted,new temporary roads,new widening roads and half closed passages are inevitable for traffic diversion.No matter which construction method is chosen,the normal traffic of the present expressway will certainly be affected.Consequently,it is a problem to be solved urgently when undergoing expansion that how to ensure the normal traffic flow,reduce the impact of new construction on it and ensure the safety of road traffic.The topic selection of this paper is exactly on the basis of the above background for the study of traffic organization design and research in the new area of interchange construction,the analysis of characteristics of traffic flow in construction section which starts from characteristic of traffic flow?traffic conflict?traffic safety as well as design and optimization of traffic organization.In combination with the new construction of Jin-Ma Expressway interchange in Ning-Huai Expressway,this paper discusses the traffic organization design during the construction of new single trumpet interchange,providing practical methods of design for other new expressway interchange construction.Finally,the Baguazhou junction Interchange Project in the western section of Puyi Highway is selected as an application case of the optimal design scheme,and the research results in this paper are applied to help the project carry out road-related construction smoothly.In the application of optimal design scheme,the traffic organization design scheme based on effective control of construction nodes and reasonable arrangement of construction period is put forward to ensure the traffic service capacity of the road-related construction section during the construction period.