Research on the Behavior Characteristics of Pedestrian Crowd Weaving Flow in Transport Terminal

Due to the poor transfer organization in urban public transport terminal, pedestrian crowd are often forced to weaving in their transfer flow lines. Frequent weaving behaviors not only decrease passengers’ transfer comfort, but may also trigger serious crowd disaster such as trampling. In order to get accurate understanding of the weaving features of pedestrian crowd and analyze the relevant evolution law, researches have been conducted on the basis of field investigation. First, the typical weaving phenomenon were defined and classified, and a microscopic parameters system of pedestrian crowd weaving flow was constructed. The detection and quantification methods of multiple indicator parameters were also given. Then, correlation between different behavioral parameters was analyzed based on the survey data of weaving pedestrian crowd on the stairs of DongZhiMen DZM hub. The basic characteristics and evolution law of the weaving behaviors were then discussed, and conclusions were drawn.


Introduction
Along with the increasing volume of transfer pedestrians, the transferring service level in some existing urban public transport terminals is greatly decreased by the crowding and interweaving pedestrian flow.How to improve the transfer efficiency of transport terminal through optimizing the organization of pedestrian flow has become an interesting thing.
In the past years, scholars at home and abroad have achieved great progress in researches about characteristics and evolution law of the weaving behaviors of pedestrian flow in transport terminals.
In 1971, Henderson analyzed the statistical characteristics of high density pedestrian flow 1 .Helbing and Molnár introduced the principle of fluid dynamics into pedestrian characteristics analysis in 1995 and carried out the numerical simulation research of pedestrian flow 2 .Since then, scholars over all countries started to conduct extensive and thorough research in pedestrian flow characteristics detection and regularity analysis 3 With the analysis and brief history above as a backdrop, it is clear that the conventional pedestrian flow studies have made progress.In recent years, scholars began to focus on several special phenomenon analysis of pedestrian flow 24-26 .As an important phenomenon of transfer activities, pedestrian crowd weaving flow generally exists in transport terminals of China 27 .Frequent intertwined behaviors in areas such as entrance, ticket hall, platform, and stairs not only decrease the transfer comfort of pedestrian crowd, but also may trigger serious crowd disaster such as trampling.It is still a problem of how to grasp the characteristics of weaving transfer pedestrian crowds and analysis the relevant evolution law accurately.
This paper describes a survey and analysis method for typical intertwined flow of pedestrian crowd.The remainder of the paper is structured as follow.Section 2 discusses the definition and classification of typical weaving phenomenon.Section 3 constructs a microscopic parameters system of weaving crowd.Section 4 presents the survey method for weaving pedestrian crowd and demonstrates its application to DZM hub in Beijing, China.Analysis results are also presented in Section 4, followed with the conclusions in Section 5.

Passenger Weaving Flow Categorization
Due to the limited space in transport terminal, there are often many conflict points among the pedestrian flow lines.Pedestrian crowd are forced to weaving at the conflict points frequently during their transfer process.Summarizing the weaving law of pedestrian crowd is the foundation to carry out analysis of various types of weaving phenomenon.In this study, weaving pedestrian crowd can be defined as a traffic phenomenon that more than two pedestrian crowd flows with transfer purpose confluence or shunt continuously in a short distance.
According to the definition and characteristics analysis of weaving pedestrian crowd, combined with field investigation, weaving phenomenon of pedestrian crowd can be classified from three aspects as follows.3 According to the boundary condition, weaving phenomenon can be divided into boundary interweave and no boundary interweave.

Characteristics of Weaving Pedestrian Crowd
Different with the conventional of pedestrian crowd, the weaving pedestrian crowd show special characteristics as follows.
1 Spatial constraint.In a transport terminal with good guidance system, pedestrian crowd usually have relatively fixed directions.But due to the limited internal space, most of the pedestrians are forced to move laterally.
2 Time constraint.Due to the impact of subway departure time, passengers arrive periodically, with high walking speed, which leading to a more frequent acceleration, deceleration, and way finding phenomenon in the weaving process.
Due to the spatial-time constraints above, pedestrian flow show more frequent crowding and collision, leading to a fluctuation of traffic density and speed.
Trajectory tracing and interaction analysis are required in the pedestrian crowd's numerical simulation.For pedestrian crowd tracks and interaction, behavior indicators which can accurately describe the pedestrian behavior are needed to explain the weaving process.Considering the spatial-time restriction of pedestrian crowd interweaving phenomenon, speed variation and lateral movement were selected together with conventional indicators such as passenger flow, average speed, average density, stride length, and frequency 28 .Definition and quantify method for indicators are as follows.
1 Pedestrian crowd volume person/meter/second : the quantity of pedestrian crowd that going through the weaving section within a unit time period as 3.1 where Q represents the pedestrian crowd flow, D represents the average density of weaving area, and V represents the average speed of pedestrian crowd in weaving area.

Mathematical Problems in Engineering
2 Average walking speed meter/second : the average time that pedestrian crowd walk through a certain distance within the weaving area as follows: where L represents walking distance, N represent the number of pedestrian crowd observed, and t i represents the walking time of pedestrian i.
3 Average density person/square meter : the quantity of pedestrian crowd within a unit area of the weaving area as 3.3 where D represents average density, Q represents the number of pedestrian crowd within the weaving area, and S represents the measure of the weaving area.
4 Stride length m : the distance that pedestrian go through by one step in weaving situation.Stride length is influenced mainly by the flow density, psychological status of pedestrian crowd, and other factors.The stride length can be estimated through the length of the floor tiles or a grid drawn on the weaving area.
5 Stride frequency number/second : the numbers of steps pedestrian walk during a unit time period in weaving situation.Stride frequency is influenced mainly by the flow density, transfer facility status, and other factors.
6 Speed variation meter/second : the maximum increase or decrease value of pedestrian crowd's walking speed within weaving area.
7 Lateral movement probability: the percentage of pedestrian that are forced to deviated from their original path due to the weaving behavior.

Investigation Method of Weaving Phenomenon
Forward-boundary-regular weaving phenomenon appears very frequently in a transport terminal, which is also the main factor reducing the hub's operation efficiency.Choose DZM station of Beijing subway as investigation object, illustrate the acquire method of weaving behavior indicators, and then analyze the characteristics of pedestrian crowd weaving flow. (

1) Investigation Time
Weaving phenomenon in a transport terminal occurs most frequently during peak hours, which has the maximum interference to terminal operation.So the investigation time was selected as working day 8:00-9:00 A.M and 17:00-18:00 P.M . (

2) Investigation Area
Weaving phenomenon of pedestrian crowd tends to occur in areas with high density and complex streamlines, such as stairs and platform areas and so forth.The connecting area between stairs and platform of DZM hub was chosen as the investigation area.Weaving behaviors within this area can be regarded as a forward-boundary-regular one. (

3) Data Collection and Analysis Method
Aiming at the characteristics of short weaving duration, high walking speed, and so forth, manual recording and video recording were combined in the investigation.Manual recording method was used to get pedestrian volume, average speed, stride length, and frequency; video recording method was used to get average density, speed variation, and lateral movement probability, as shown in Table 1. Figure 2 shows the distribution of data collection points.
A statistical analysis of the walking speed and pedestrian crowd density were conducted, results show that the weaving phenomenon takes 140 seconds for a periodic regularity of occurrence and dissipation, as shown in Figures 3 and 4.This meets the actual arrival and departure regularity of metro vehicle.
On these basis, record the related parameters of interweave phenomena by the cycle of 140 seconds according to weaving phenomenon occurrence regularity, get the relationship between pedestrian crowd volume, speed, and density of interweaving phenomenon, as shown in Figures 5, 6 and 7, the value of other related indicators are shown in Table 2.

Conclusions
Aiming at the pedestrian weaving behavior in transport terminal, this paper defined and classified the pedestrian crowd weaving flow and constructed a characteristic indicator system.The investigation and quantization methods for indicators were also given.Then summarize the basic regularity of pedestrian crowd interweaving phenomenon through field

- 9 .
Ukkusuri et al. 10 , Laxman et al. 11 and Lam et al. 12 studied the characteristics of pedestrian flow at certain transportation facilities.Siram et al. 13 , Zhou et al. 14 , and Wang et al. 15 explained the particular phenomenon in elderly pedestrians and paired pedestrians.Hughes 16 gave the maximum speed and density of pedestrian flow.The relationship between pedestrian speed and density was studied by Ando et al. 17 , Thompson and Marchant 18 , Hughes 19 , Hankin and Wright 20 , and so on.Cheung and Lam 21 and Tanaboriboon et al. 22 studied the relationship between pedestrian volume and density.On this basis, the 2010 issue of the American Capacity Manual summarized the characteristics of most types of pedestrian flow 23 .

Figure 1 :
Figure 1: Schematic diagram of weaving pedestrian crowd-forward weaving flow a , cross weaving flow b , and lateral weaving flow c .

2 )Figure 6 :
Figure 6: Correlation between the pedestrian crowd volume and average density of pedestrian crowd.

Figure 7 :
Figure 7: Correlativity between the pedestrian crowd volume and average walking speed.

Table 1 :
Investigate methods for behavior indicators of weaving pedestrian crowd.

Table 2 :
Behavior indicator data of weaving pedestrian crowd flow.