Study On Coordinated Setting Of Ultra-short Weaving Area And Bus Stop On Expressway

As an important road in the urban transportation network,expressways undertake the task of large-scale,long-distance and rapid transportation services in the city.With the growth of urban residents’ travel demand and the rapid increase in the number of motor vehicles,expressway congestion has gradually become a common problem.As a concentrated section of confluence and diversion,the ultra-short interwoven area has many vehicle conflicts,and bus stops are set up nearby,which will further aggravate the traffic flow disorder and form congestion during peak hours.Properly adjusting the location of bus stops within a limited range can reduce its impact on the interwoven traffic flow,thereby reducing the delay in the ultra-short interwoven area.Therefore,this paper explores the coordinated setting of bus stops and ultra-short intertwined areas with the purpose of minimizing overall delay and maximizing traffic efficiency,and the main contents are as follows:Firstly,the short interwoven area of the third and fourth ring expressways in Beijing is counted,the concept and operation characteristics of the ultra-short interwoven area are proposed,and the upstream traffic flow characteristics,lane traffic distribution,interwoven traffic flow characteristics,non-interwoven traffic flow characteristics,and bus stop characteristics of the ultra-short interwoven area are analyzed through on-site observation.Secondly,the influence of bus stop setting on traffic flow in ultra-short interwoven area is analyzed by situation,and the minimum spacing definition and calculation model are proposed.When the bus stop is set upstream of the ultra-short interwoven area,the main consideration is to reduce the impact of bus entry and exit on exiting vehicles.The calculation method of minimum spacing is discussed in two cases: small spacing and large spacing,and it is proposed that the minimum spacing should be the maximum of the two,because the operation of the ultra-short interleaved zone is complex,and the incoming traffic flow and the outgoing traffic flow interfere with each other,and the correction coefficient of the incoming traffic flow is added to the formula of the minimum spacing.Thirdly,based on continuous cellular automata,an ultra-short interleaved region simulation model is constructed.Using the improved gipps following rule as the vehicle following rule,the STCA lane change rule with variable safety distance is constructed.At the same time,according to the different operating characteristics of traffic flow in and near the ultra-short interwoven area,the model is divided into normal driving area,bus stop area and interwoven lane change area,and the bus priority lane change rule is set,and the bus exit influence time is introduced for the slow acceleration of bus exit.The actual observation data of traffic flow in ultra-short interwoven area is used as a reference to calibrate the simulation model.Finally,taking the bus stop in the upstream of the ultra-short interwoven area as an example,the impact on the traffic flow in the ultra-short interwoven area of the main road and its vicinity is studied by considering the changes of the spacing between the bus stop and the ultra-short interwoven area,the upstream traffic of the main road,the upstream traffic of the auxiliary road,and the bus arrival rate.Through scheme design,simulation experiment and evaluation index analysis,the influence law of spacing under different flow rates on the ultrashort interwoven area is obtained,the recommended interval of bus stops is given,and the coefficients in the minimum spacing calculation model are calibrated.