Nirajan Shiwakoti

Nest architecture and traffic flow: Large potential effects from small structural features

1. Research on human pedestrian dynamics predicts that seemingly small architectural features of the surroundings can have large effects on the behaviour of crowds and the flow of pedestrian traffic, particularly when a crowd is panicked. This theoretical framework might usefully be applied to the study of collective movement within subterranean nests of social insects.

Biologically Inspired Modeling Approach for Collective Pedestrian Dynamics Under Emergency Conditions

An interesting aspect of collective dynamics of various biological entities is that they are emergent systems. A literature review examines how the fundamental principles of emergent systems can be applied to model collective pedestrian dynamics. A simulation model is then proposed on the basis of modifications of collective animal dynamics. Recent findings from experiments with panicking Argentine ants are presented to illustrate how such experiments can be used to study collective pedestrian traffic. Despite the difference in speed, size, and other biological details of the panicking individuals, the model proved capable of explaining the collective dynamics. The models robustness is demonstrated by comparing its ability to simulate the collective traffic of panicking ants as well as collective human traffic. The lack of complementary data during emergency and panic situations is a challenge for model development. Empirical data from biological organisms can play a valuable role in the development of pedestrian traffic models from a theoretical perspective and in instances in which model validation is based on empirical data collected by video. Such a novel framework, which is based on complementary expertise, can be used as a basis for the design of solutions for the safe egress of pedestrians.

Social Media Use during Unplanned Transit Network Disruptions: A Review of Literature

Abstract This paper explores social medias role in managing unplanned transit networks disruptions. Although literature exists more broadly on the use of social media in transit, this paper presents the first literature review in this setting. When disruptions occur, commuters require reliable, up-to-date information. Its provision reduces anxiety and allows informed choices. Social media is beneficial given it provides real-time information but it can only supplement (not replace) conventional approaches. Information reliability was critical. Research in the field of disaster management illustrates the importance of publicly contributed information. Known as “crowdsourcing”, it is part of the emerging field of crisis informatics which for the first time was linked to unplanned transit disruption management. The results highlight that social medias real-time nature can reduce disrupted travel demand; however, its utilisation can be resource-intensive. A framework presented illustrates how social media utilisation varies according to the operational characteristics of a disrupted network. Social media use as an information delivery tool is still in its infancy and an unwillingness to embrace it is an impediment to sustained growth. Crowdsourcing is one approach that could resolve the issue of transit agency resourcing whilst satisfying the increased demand and expectation for real-time information.

Disruption Recovery in Passenger Railways

This research paper explores the manner in which passenger rail transit organizations plan for and manage unplanned service disruptions through an international survey of practices. The research reported here included semistructured interviews of those staff responsible for service disruption management within 71 international transit agencies. Results suggested that 20% of agencies had parallel transit systems that could be used by commuters whose service was disrupted. Most of these systems existed in inner-city contexts. Track intrusions, medical emergencies, weather extremes, and track and rolling stock failures were common causes of unplanned disruptions. Bus bridging was the most common response to line blockages, while transfer of passengers to the next train was the most common approach to individual rolling stock failures. Track crossovers were widely seen as critical to manage responses to disruptions. A small minority, mostly in cold climates, also saw crossovers as a cause of unplanned failures. Most agencies used spare buses as bus-bridging vehicles. Only 45% actively retracted buses from existing scheduled bus services. Some of these agencies did acknowledge that retraction often was done in extenuating circumstances, however. Rarely did agencies have a strategic reserve of buses for bus-bridging purposes. This paper discusses the implications of the study findings for further research and practice. This paper also documents that all responses to unplanned disruptions can be categorized according to the key disruption characteristics of duration, cause, time, and location, and it provides a typology of response mechanisms on the basis of such characteristics.

Consequence of turning movements in pedestrian crowds during emergency egress

Collective egress comes into play during emergencies such as natural disasters or terrorist attacks, when rapid egress is essential for escape. An important aspect of collective egress under emergency conditions is the turning movement when a sudden change in the direction or the layout of the escape area occurs. Previous case studies of crowd disasters have highlighted the importance of such turning movements; however, both qualitative and quantitative studies seldom address this phenomenon specifically for emergency and panic situations. The paucity of complementary data on human panic presents a considerable challenge to undertaking quantitative analysis. The study described in this paper uses empirical data from real-life video footage of a crowd stampede and from panicking ants, paired with a simulation model, to demonstrate how potential problems and consequences of turning movements during collective dynamics can be studied. With this modeling tool, it may be possible to develop evacuation strategies and design solutions that can prevent stampedes and trampling, which occur when large groups of people try to escape from confined spaces where escape path directions abruptly change.

Pedestrian Walking Characteristics Through Angled Corridors: An Experimental Study

Understanding pedestrian walking characteristics is important for the planning and design of mass gathering places for day-to-day activities as well as for emergency evacuations. The optimization of architectural designs and properly managing crowds at public buildings and the built environment is essential to ensure the safety and efficiency of crowd dynamics. Most previous empirical and theoretical studies highlight the behavior of a crowd as a whole system (macroscopic behavior) or interpersonal microscopic interactions within the crowd. A major gap in the knowledge is that no sufficient research has been carried out to examine solo walking characteristics, particularly when individual pedestrians interact with complex geometries such as turning. Whether the existing mathematical or simulation models can accurately reflect the characteristics related to solo human walking characteristics in these conditions is questionable. A series of experiments was conducted to understand the solo walking characteristics of individuals walking through angled corridors at different speeds. Initial results are discussed in detail. Results suggest that an individual tends to reduce speeds within a fixed region on the angled path and that the dimensions of this region are independent of turning angle but dependent on the individuals desired speed. These findings are important for the calibration of parameters or behavioral rules for microscopic pedestrian models.

Understanding Crowd Panic at Turning and Intersection Through Model Organisms

Previous studies on crowd disasters have highlighted the importance of considering turning and intersecting movement patterns in an escape area. Given the scarcity of data on human panic, there may be merit to use insights from non-human organisms to understand crowd panic as collective behaviour patterns also occur in non-human biological systems. We use model organisms approach by examining empirical data collected from panicking Argentine ants to study crowd panic at turning and intersection. The empirical data showed that the outflow of ants do not decrease proportionately with the increase in turning angles. Likewise, at intersection it was observed that one stream of ants is blocked by another stream of ants for considerable duration resulting in disproportionate flow at the intersection. Although the results are preliminary for statistical significance, these can have implications in testing the models of pedestrian crowds and in development of design solutions that enhances crowd safety.

International Study of Current and Potential Social Media Applications in Unplanned Passenger Rail Disruptions

This paper presents research on the role that social media play in the management of unplanned passenger rail disruptions. The study incorporated an international survey of 86 agencies on current practice and a case study on social media use in Melbourne, Victoria, Australia. Research literature on social media in transit is limited; this paper presents the first analysis of their practical use during unplanned passenger rail disruptions. When disruptions occur, passengers need reliable, up-to-date information, which should be transparent and sympathetic to the impact of delays on passengers. Social media are useful during disruptions, because social media enable concise, real-time information to be provided and enable passengers to make informed, proactive choices in commonly reactive and suboptimal situations. Passengers have greater opportunity to take control of their situation as a result of social media communication. The international survey results indicated that 86% of the agencies used Twitter, 33% used Facebook, and only 12% did not use social media. Twitter was prevalent in high-frequency networks; its real-time nature provided the most appeal. Social media benefited soon-to-travel commuters the most and enabled proactive selection of alternative travel and nontravel options. The needs for support staff resources and skills were identified as impediments to social media deployment. Rail agencies also reported that the management of commuter expectations in the use of social media was a growing concern. A conceptual model for the social media impact on disruptions is developed in the paper on the basis of the research findings. The paper discusses future research and practice opportunities.

Examining the Impact of Different Turning Angles on the Collective Egress of Crowds

Previous case studies of crowd disasters highlighted that collective human behaviors associated with common manoeuvres, such as turning movements, can be potentially dangerous particularly under emergency conditions. Therefore, proper consideration should be given when designing physical features such as angled or circuitous pathways at crowd-gathering places. A major gap in the knowledge is that no substantial research has examined crowding and turning-angle impacts on collective egress of crowds. In this study, to investigate the influence of turning angle on collective crowd behaviors, the authors utilize empirical data collected from human trials under normal walking conditions and from ants under panic conditions. Results obtained from analyzing empirical data from human trials suggest that higher turning angles (e.g., 60° or more) are inefficient in terms of significantly reducing the flow rates and velocities under normal/orderly evacuation conditions. This threshold angle could be reduced (e.g., up to 45°) under panic conditions, as verified with experiments with ants under panic conditions. These empirical studies are beneficial for calibration and validation purposes of the explanatory models and contribute to the development of effective evacuation strategies and design solutions for public buildings and urban environment.

Congestion Pricing with Distance Tolls: A Review and New Developments

This paper discusses the optimal toll design problem of cordon-based pricing with nonlinear distance tolls. In the previous studies, however, the cordon-based congestion pricing scheme usually takes the area-based pricing scheme or a flat toll charge method, which are not equitable and efficient. Thus, distance tolls are recently proposed by the researchers to be the new generation of cordon-based pricing. An in-depth review is first provided on the state-of-arts of the addressed topic. Then, using the similar bi-level formulation framework, some formulations are first provided in the context of stochastic user equilibrium, including four different formulations for the stochastic social optimum.