Modeling And Analysis Of Traffic Efficiency Of Linked Evacuation Segments In Metro Stations

Nowadays,the rapid growth of urban population density poses challenges in travel aspects.The transportation systems of many cities are difficult to meet the increasing demand for commuting passengers.The emergence of metro has successfully improved the travel efficiency and alleviated urban traffic congestion caused by massive population.Therefore,the rail transport has developed rapidly.Many cities gradually carry out the construction of metro system.With the completion and use of the metro system,it has become one of the main ways of transportation for people to go to school or go shopping.After getting off the train,passengers arrive at the platform,where they then go to the station concourse through escalators or stairs.In the concourse,they can select one of the auto-fare collection gates to enter the unpaid area.Finally,they exit through the station exit.The entire traveling process on different segments forms a link.This link is usually used by passengers to evacuate,so it is named as evacuation link hereinafter.Existing researches have barely focused on the pedestrian traffic efficiency of evacuation links.It has been noticed that due to the large passenger flow in the metro station,accidents can be easily triggered.As an important factor affecting the degree of congestion in the station,it is necessary to carry out in-depth study on the traffic efficiency of evacuation links.Therefore,this paper specifically analyzes the pedestrian traffic efficiency of facilities,i.e.,evacuation link segments in metro stations and the whole evacuation link by establishing multi-grid models.Firstly,the capacity of escalators under different combinations of elevator operation modes was investigated by establishing a multi-grid escalator model.The results showed that the escalator velocity v _E and the pedestrian velocity v _H are the key factors affecting the escalator's capacity.Therefore,compared with stairs,the use of escalators contributes to improve the capacity.The velocity of escalators will effectively mitigate the impact of the interval on capacity.When some pedestrians are walking on the left-side and meanwhile some pedestrians are standing on the right-side of the escalator,the velocity of pedestrian v _Hhas no obvious effect on the capacity of escalators.By comparing and analyzing the relevant results,we found that it can't ensure a higher capacity when pedestrians walk on the escalators.Secondly,based on the improved“Togawa”empirical formula,a multi-grid auto-fare collection gate selection model is established to explore pedestrian's selection behavior and the efficiency of the gates under the influence of factors,including gates distribution,entrance location and scene width D.The simulation results indicate when choosing a gate,pedestrians will consider the distribution of the gate,the number of people in the queue,the distance and so on.This behavior directly affects the traffic efficiency of the gate.In the case of different gate distribution,pedestrians are more willing to choose a closer gate to pass through.With the increase of amount of people queuing in front of the gate,a pedestrian may choose a farther gate to ease the congestion.When the entrance is located in the central simulation scene,the efficiency of the middle gate is higher,and the efficiency of gates on both sides is lower.When the entrance is set on the right side of the simulation scene,there are many people queuing in front of the gate and pedestrians on the right rarely choose the gate on the left,even if they are severely blocked.The Logit Model of escalator selection behavior is at last established to study whether a pedestrian select a staircase or an escalator on platform.Factors including the queuing number N,the space that peoples can occupy W and the height H are taken as the main factors influencing the choice of stairs or escalators.By counting and analyzing of pedestrian escalator selection behavior videos at Xipu station and Luomashi station during commuting hours,it was shown that the ratio of pedestrians choosing stairs or escalators was 0.3:0.7,which was used to calibrate the parameters of the Logit Model.Eventually,the model parameters were determined as:k _W=0.4,k _H=0.2,k _N=-0.3,and the data obtained from the video of Luoma shi station verified the model.The above different models were finally incorporated in a multi-grid model to study the efficiency of escalator,stair/escalator and auto-fare collection gate combined evacuation link.Using this model,we explored the relationship between the evacuation link efficiency and the influential factors such as the total number of pedestrians,escalator speed v_E,the number of auto-fare collection gates N_G.Meanwhile,we compared and analyzed the efficiency of passing through different pedestrian facilities.The results show that the travel time of evacuation link increases with the total number of people increases.When the amount of people is small,the time for pedestrians to pass through the door is approximately the same as the time to pass the gates.When the number of people increases,it takes more time to pass gates than doors,which proves again that the gates are the bottleneck in the evacuation link and the setting of more gates helps to alleviate the blockage of high-density crowds.Therefore,appropriate number of gates should be set in the metro station according to the daily passenger flow.The results of this paper contribute to quantify the main factors affecting the traffic efficiency segmented evacuation link,i.e.,pedestrian facilities and the evacuation link as a whole in metro stations.It can be used to identify evacuation bottlenecks in the stations,thus providing theoretical support and practical guidance for metro stations management departments to work out facility operation plans,crowd flow management strategies and so on.