Reducing the impact of speed dispersion on subway corridor flow

Highlights

• Speed dispersion in corridors leads to speed mutations and path/time variations.

• A relationship between pedestrian management and pedestrian traffic is proposed.

• A guardrail is the best measure to reduce speed dispersion.

• The optimal guardrail position allows 2/3 of the corridor for fast pedestrians.

Abstract

The rapid increase in the volume of subway passengers in Beijing has necessitated higher requirements for the safety and efficiency of subway corridors. Speed dispersion is an important factor that affects safety and efficiency. This paper aims to analyze the management control methods for reducing pedestrian speed dispersion in subways. The characteristics of the speed dispersion of pedestrian flow were analyzed according to field videos. The control measurements which were conducted by placing traffic signs, yellow marking, and guardrail were proposed to alleviate speed dispersion. The results showed that the methods of placing traffic signs, yellow marking, and a guardrail improved safety and efficiency for all four volumes of pedestrian traffic flow, and the best-performing control measurement was guardrails. Furthermore, guardrails’ optimal position and design measurements were explored. The research findings provide a rationale for subway managers in optimizing pedestrian traffic flow in subway corridors.

Introduction

With urbanization and subway network expansion in China, the average daily passenger traffic (ADPT) of the subway has been growing. Speed dispersion, caused by the variation in pedestrian walking speeds, frequently occurs in the subway, with the potential to substantially affect pedestrians’ sense of comfort and cause serious safety hazards. A new task for subway operational management is to provide passengers with a safe and efficient walking experience.

Studies have been developed to use advanced data collection technologies to characterize pedestrian traffic for improving the efficiency of pedestrian flow (Hughes, 2002, Guo et al., 2010, Ye et al., 2008). Pedestrian speed has been studied by analyzing characteristics such as pedestrian gender (Shi et al., 2007, Young, 1999), pedestrian age (Fitzpatrick et al., 2006, Montufar et al., 2007, Young, 1999), the effects of carrying luggage (Ye et al., 2012), and the pedestrian's social group (Zhao et al., 2016). Other studies have explored environmental conditions such as different facilities (Al-Azzawi and Raeside, 2007, Fujiyama and Tyler, 2010, Sun et al., 2017), passenger flow weaving (Sun et al., 2014), weather and season (Aultman-Hall et al., 2009), and the evacuation environment (Zhao et al., 2017). With the rise of mobile phone usage, the adverse influence of phone distraction on pedestrian traffic has also been studied (Bungum et al., 2005, Dunbar et al., 2004, Hatfield and Murphy, 2007, Schwebel et al., 2009, Stavrinos et al., 2009, Whitebread and Neilson, 1999). These studies showed that different types of pedestrians, pedestrian experiences, and pedestrians environments result in different pedestrian speeds.

The influence of speed dispersion in traffic has been well studied (Chung and Recker, 2014, Graham and Chenu, 1962). Shankar and Mannering (1998) investigated the fundamental factors of speed dispersion and explored the relationship between speed dispersion and average speed. Shankar and Mannering (1998) proposed a structural model that related mean speed and speed deviation. Wang et al. (2007) suggested that speed dispersion could be defined as either the standard deviation of the single speed or the average speed difference between two adjacent vehicles.

Studies have also focused on the influence of speed dispersion on traffic accidents (Helbing, 1996, Hoogendoorn and Bovy, 2000). Models for the relationship between traffic speed and accident rates (or casualty rates) have been built to analyze the impact of speed dispersion qualitatively and quantitatively (Cassidy, 1998, Del Castillo and Benitez, 1995, Liu and Popoff, 1997, Shankar and Mannering, 1998). An earlier study found that speed dispersion plays a key role in various ways: for instance, traffic safety studies have shown that pedestrian safety is threatened by speed dispersion, which also affects travel reliability and operating efficiency (Chung and Recker, 2014).

The study of speed dispersion has been an important area of study. However, the optimal management of speed dispersion which aims to improve the stability of traffic flow and avoid traffic collisions has rarely been studied, especially in pedestrian traffic. This study explored the characteristics of pedestrian speed and behavior in the subway. First, unidirectional pedestrian traffic flow in the subway was investigated through analyzing field videos. Second, three management techniques – hanging traffic signs, yellow marking, and installing a guardrail were used to test efficiency and safety in a subway station environment. Pedestrian experiments with four levels of pedestrian volumes were conducted to mimic a real-world subway corridor. The effectiveness of the management methods was demonstrated through a before-and-after comparison, and the speed and turning angle can be considered as analysis parameters. Third, the optimal position of the guardrail was explored by conducting pedestrian experiments. Finally, the experiments were compared with a real subway station environment for authenticity.