Study On Key Technologies In Expressway Maintenance Work-zone Traffic Organization Optimization

By July,2013,78.5percent of the expressway network in China has been constructed ina rapid speed. Because of such characteristics as rapid increase of traffic volume, largepercent of heavy vehicles and single vehicle excessive overloading of the traffic andtransportation in China, expressways built earlier can no longer satisfy the needs of the bigtransportation development either in undertaking operational capability or in pavementdriving comfort. Therefore, reconstruction, expansion and local road maintenance projects ofexpressway will increase dramatically. The reconstruction, expansion and maintenanceprojects will inevitably influence the traffic smooth and safety of the normal road section. Toguarantee a higher traffic capacity of the work road section and not lower the safety of trafficand construction, it is very necessary to work out a traffic organizational scheme of workzone scientifically and efficiently.Firstly, with reference to the research methods and achievements of relevant fields athome and abroad, data investigation and analysis is carried out in such aspects as traffic flowcharacteristic, characteristic of drivers, road characteristic and vehicles driving characteristicwhich have an influence on the traffic organization of the work zone. Based on thecharacteristics of influence factors and the trial operation of traffic organization plan, Vissimmicro traffic simulation is adopted to evaluate the parameters and the scheme to achieve therepeatability of scheme design and evaluation.Secondly, based on the relevant technical specifications of traffic organization formaintenance work, combining several successful reconstruction and expansion projectsimplementing cases of maintaining traffic moving, key parameters and flow of trafficorganization scheme design are made clear. Aiming at the fact that traffic organizationscheme must satisfy the principle of fluent traffic and safety, evaluation indexes are comparedand selected scientifically and evaluation method applicable to many indexes is put forwardin order to build the evaluation system aiming at key parameters and traffic organizationscheme.At last, the most two common types of traffic lane closure mode of two-way four-laneexpressway, namely outer(inner)lane closure mode and half of the road closure and median strip opening mode, are analyzed. Optimized speed limit mode (400m,80km/h limited;1200m,60km/h limited; in warning area)is proposed with reference to relevant regulations ofministry of communication and local regions, and threshold value of suggested design lengthof work zone is put forward based on the serviceability level of the work zone section.Further aiming at the mode of closing half of the road and opening median strip, reasonableopening length (80m) of median strip meeting certain traffic smooth and safety is proposedfrom the respect of vehicle path theory and simulation. It is also suggested that the vehiclesconverge to single lane within a certain distance (transition section of the confluence:80m;combined buffer section:100m) before the opening of the median strip to enable steadytraffic flow crossing median strip smoothly.