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    Traffic Flow on Escalators and Moving Walkways:

    Quantifying and Modeling Pedestrian Behavior in a Continuously Moving System

    Peter D. Kauffmann

    Thesis submitted to the faculty of the

    Virginia Polytechnic Institute and State University in partial fulfillment of the requirements for the degree of

    Master of Science

    In

    Civil Engineering

    Dr. Shinya Kikuchi

    Dr. Antoine Hobeika

    Dr. Ralph Buehler

    February 4, 2011

    Falls Church, Virginia

    Keywords: escalator, moving walkway, cellular automata, pedestrian, capacity

    Copyright ? 2011 by Peter D. Kauffmann

    Traffic Flow on Escalators and Moving Walkways:

    Quantifying and Modeling Pedestrian Behavior in a Continuously Moving System

    By

    Peter D. Kauffmann

    ABSTRACT

    (Enter abstract here)

Acknowledgements

    Thank some people.

    Kikuchi

    Committee: Hobeika for the “how”, Buehler for the “why”

    Greg and Brad for encouraging me to go on trips during the formative phase of my thesis that wound up being heavy in escalator and moving walkway usage

    Connor and Dymond for giving me something to do to support myself financially while I got my act together in grad school

    TISE faculty for providing suitably significant projects that I now understand are preparation for larger research undertakings, specifically Rakha, Abbas, Hobeika, and Kikuchi Parents for not asking questions about when I was going to finish up

    CEE office staff for support with teleconferencing with committee

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Table of Contents

    Chapter 1: Introduction to Moving Belts .................................................................................1 1.1 Prevalence of Escalators and Moving Walkways ........................................................... 1 1.2 History and Development of Moving Belt Systems ........................................................ 2 1.3 Design of Pedestrian Interface Areas ............................................................................. 2 1.3.1 Necessary Simplifications ........................................................................................ 3 1.3.2 Flaws in Belt Specification ...................................................................................... 3

    1.3.2.1 Determining Capacity ....................................................................................... 3

    1.3.2.2 Accounting for Regional Differences in Pedestrian Streams .............................. 4

    1.3.2.3 Effects of Crush Loading .................................................................................. 4 1.4 Proposed Approach to Belt Capacity Analysis ............................................................... 4 1.4.1 Model Operation ...................................................................................................... 4 1.4.2 Source Data ............................................................................................................. 5

    1.4.2.1 Inclusion of Automotive Choice Behavior ........................................................ 5

    1.4.2.2 Sensitivity Analysis Capabilities ....................................................................... 5 Chapter 2: Literature Review ...................................................................................................6 2.1 Pedestrian Behavior ....................................................................................................... 6 2.1.1 Unrestricted Condition ............................................................................................. 6

    2.1.1.1 Travel Characteristics ....................................................................................... 6

    2.1.1.2 Available Space ................................................................................................ 7 2.1.2 Confounding Factors ............................................................................................... 8

    2.1.2.1 Stair Climbing .................................................................................................. 8

    2.1.2.2 Elevation Change .............................................................................................. 9

    2.1.2.3 Bottleneck Effects............................................................................................. 9

    2.1.2.4 Following Behavior .........................................................................................10

    2.1.2.5 Passing Choice ................................................................................................11 2.2 Traffic Flow Theory .....................................................................................................12 2.2.1 Following Behavior ................................................................................................12

    2.2.1.1 Existing Derived Equation Models...................................................................12

    2.2.1.2 Rule-Based Models ..........................................................................................13 2.2.2 Passing Choice .......................................................................................................14 2.3 Belt Characteristics.......................................................................................................14 2.3.1 Geometric Specifications ........................................................................................15 2.3.2 Operational Parameters ...........................................................................................15 2.4 Capacity Analysis .........................................................................................................16 2.4.1 Empirical Capacities ...............................................................................................16 2.4.2 Level of Service Determination ..............................................................................16 2.5 Modeling Framework ...................................................................................................17 2.5.1 Simulation Approach ..............................................................................................17

    2.5.1.1 Cellular Automata (CA) Framework ................................................................17

    2.5.1.2 CA Approach to Pedestrian Flow Modeling .....................................................17

    2.5.1.3 Criticism of CA Approach ...............................................................................18

    2.5.1.4 Calibration of Model Parameters......................................................................18 2.5.2 Modeling Language ................................................................................................19 Chapter 3: Model Development .............................................................................................. 20

     iv

     Framework ...................................................................................................................20 3.1

    3.1.1 Pedestrian Parameter Selection ...............................................................................20

    3.1.2 Belt Characteristics .................................................................................................20 3.2 Operation .....................................................................................................................20

    3.2.1 Formulating Inflow .................................................................................................20

    3.2.2 Inducing Movement ................................................................................................20

    3.2.3 Accounting for Confounding Factors ......................................................................20

    3.2.4 Implementing Pedestrian Interaction .......................................................................20 3.3 Data Collection.............................................................................................................20

    3.3.1 Real-Time Outputs .................................................................................................20

    3.3.2 Time-Space Diagrams.............................................................................................20

    3.3.3 Capacity Analysis ...................................................................................................20 Chapter 4: Results and Discussion ......................................................................................... 21 4.1 Model Validation..........................................................................................................21

    4.1.1 Operation ................................................................................................................21

    4.1.1.1 Following ........................................................................................................21

    4.1.1.2 Passing ............................................................................................................21

    4.1.1.3 Bottleneck Effects............................................................................................21

    4.1.2 Capacity .................................................................................................................21 4.2 Potential Applications ..................................................................................................21

    4.2.1 Sensitivity Analysis of Proposed Solutions .............................................................21

    4.2.2 Analysis of Proposed Rule Implementation.............................................................21

    4.2.3 Platform Sizing .......................................................................................................21 Chapter 5: Conclusions ........................................................................................................... 22 5.1 Suggestions for Further Research .................................................................................22 References................................................................................................................................ 23 Appendix ................................................................................................................................. 26

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Chapter 1: Introduction to Moving Belts

    In the early days of urban transportation, achieving mobility was not difficult. Travelers could, given enough time, walk to whatever destination they needed to reach. If necessary, a horse or carriage might be used. However, as humanity became more and more dispersed, it became necessary to develop alternate modes to speed up travel within urban areas. In contemporary society, cities require tremendous transportation networks to handle the needs of their citizens. However, even with this reliance on mechanized modes like automobiles, buses, and trains, the need to accommodate pedestrians remains paramount.

    In many public facilities like transit centers, airports, and even shopping centers, conglomeration has occurred in order to gain the efficiencies of scale. Because of this, these structures have become so large that their designers cannot reasonably expect the average user to travel across the facility by means of walking alone, at least not in a timely manner. To this end, engineers and inventors have spent the last century developing innovations that can speed up pedestrians and facilitate movement through urban interface areas.

    1.1 Prevalence of Escalators and Moving Walkways

    Today, escalators and moving walkways have become an integral part of the urban aesthetic. Travelers have come to expect the presence of these enabling devices in most if not all significant public facilities. Escalators have become commonplace wherever elevation change is present, both to allow pedestrians to traverse a longer distance than normal even when carrying luggage and also to keep the flow of travelers at a stable and high rate even in the presence of vertical obstacles. Similarly, moving walkways have seen widespread implementation in dispersed facilities like airports, which are spread out by necessity, or adjacent transit stations, which may be connected to facilitate transfers between lines.

    Both devices provide several key benefits. First, they serve to reduce overall travel time across a facility. At the same time, moving belt systems also increase both the horizontal and vertical distances that pedestrians are able to traverse by reducing the level of physical effort that must be expended. Finally, and perhaps most importantly in the context of a high-traffic area like a transit station, the presence of an escalator or moving walkway improves the overall flow through an otherwise constricted area. By conveying all passengers along at a constant rate, the belt creates some minimum speed at which all riders must travel. The conveyance of the belt both serves to increase throughput while at the same time decreases the speed differential through the constriction, therefore reducing conflicts.

    Despite the benefits that escalators and moving walkways provide, their numbers are limited by virtue of the limited number of public facilities where their usage is required. While it may be true that in high capacity, low-rise facilities there are few alternatives to escalators for movement, in the vast majority of hospitals, office buildings, and apartment buildings this purpose is fulfilled by the elevator. To this end, while the 30,000 escalators in operation in the United States (Slaughter, 2004) may seem like a large quantity, this number pales in comparison to the 700,000 elevators in operation (Hession). However, while there may have been over twenty times as many elevators, they only carried slightly more passengers. In the US and Canada, there are 325 million elevator passengers per day compared to 245 million escalators passengers

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Peter D. Kauffmann Chapter 1: Introduction to Moving Belts 2

    per day (Hession). Therefore, it can be seen that despite their relatively limited number, escalators and moving walks on average carry a much greater load per unit.

    1.2 History and Development of Moving Belt Systems

    The development of moving belt technology was spread out over several decades, and indeed still continues to this day. The first patent for such technology on record was filed in August of 1859 by Nathan Ames for an invention he called “revolving stairs.” This device, while crude and immensely dangerous by modern standards, was the first to include a progression of horizontal step-like surfaces called “cleats” – for standing (Ames, 1859). Earlier models had

    instead consisted of a simple belt with regularly spaced wooden slats to provide traction (Lampugnani, Hartwig, Simmen, & Imorde, 1994).

    However, the first modern version of the escalator as it is known today was premiered by the Otis Elevator Corporation at the Paris Exposition in 1900. Practically all contemporary escalators follow the model laid out by Otis. Safety features that were introduced in this model include side balustrades for support. However, the most noteworthy innovation of the Otis escalator was the inclusion of a number of flat steps at the entry and exit points to facilitate loading and unloading (O'Neill, 1974). By adding in space for two and later three

    consecutive cleats to leave their step treads in a horizontal position, the escalator allows its passengers enough time to establish themselves on a single step before the belt transitions to the inclined regime of steps.

    With time, further developments in escalator technology have emerged, from handrails that move along with the steps to interlocking cleat designs that significantly reduce the risk of foot entrapment (Lampugnani, Hartwig, Simmen, & Imorde, 1994). However, it is interesting to note that throughout the last century escalator technology was developed much earlier than that of moving walkways. Although both types of moving belt systems are now comparable to one another, it is intriguing that the complicated, torque-intensive, and frankly dangerous system that makes up an escalator was developed in advance of the vastly simpler moving walkway. In light of the fact that it is only with the relatively recent advent of large indoor facilities that such a device is required, this lag begins to make sense.

    1.3 Design of Pedestrian Interface Areas

    When designing public facilities, one aspect of importance to consider is that of pedestrian flow within the facility. Even the most attractive and functional structure will be unsuccessful if it proves to be too difficult for its users to traverse. Although a moving belt will not necessarily transform a structure that is dispersed horizontally or vertically into something with a tightly linked and effective floorplan, the inclusion of these systems can go a long way in bringing a spread-out structure closer together. Furthermore, even in a situation where a moving belt is not needed because of distance, their inclusion can help to promote rider comfort and convenience (O'Neill, 1974).

    To this end, architects and engineers must be sure to consider the dynamics of pedestrian circulation when developing these structures. Interface areas generally include facilities where there is a change of mode or vehicle, a characteristic perhaps best exemplified by a transportation station like a train station or airport. However, a shopping complex, office building, or other

Peter D. Kauffmann Chapter 1: Introduction to Moving Belts 3

    large public structure could also count in this category because of the fact that users must transition from the mode of their arrival to whatever activity may be occurring at the endpoint of their trip. The important behavior to note is the presence of pedestrian circulation within the facility, and consequently how this action is treated in the design phase.

    1.3.1 Necessary Simplifications

    Although the capability exists to simulate the movement of crowds throughout a facility, only a small percentage of interface areas are subjected to this level of analysis. Typically, simulation is only performed in facilities where crush loading conditions may occur that will create unsafe conditions for users. However, even in this situation, it is more common for designers to use architectural standards to determine the width of a corridor or the number of exit doors required based on the projected flow of people along that particular path.

    With regards to escalators and moving belts, design is typically performed by determining the normal and peak loading of users who desire to travel along a particular locomotive corridor. For instance, a designer may know that during rush hour there may be some number of people who desire to exit an underground subway station. Through the use of published architectural standards or projected loading curves, they can determine how many escalators will be needed to handle the outbound flow. Unfortunately, there are a number of flaws and imperfections that are present in this approach.

    1.3.2 Flaws in Belt Specification

    In the scenario described above, a designer wants to determine what configuration of escalators is necessary for subway installation. The current state of the practice would involve conducting research in a published manual or manufacturer’s guidelines to determine the capacity of a given escalator configuration and then determining the quantity and specifications needed to meet demand. However, this method may prove to be unacceptably inaccurate under certain conditions.

    1.3.2.1 Determining Capacity

    At present, the capacity of an escalator or moving walkway is determined by looking at a manufacturer publication and finding the “practical capacity” based on the speed of operation permitted by that locality (ThyssenKrupp Elevator, 2004). Unfortunately, the methods behind this method are somewhat oversimplified.

    To determine the practical capacity, the manufacturer first computes the theoretical transport capacity, which is equal to the number of treads per hour times the number of people each step can support. In conventional installations with a speed of 0.5 m/s, a tread depth of 0.4 m, and a tread with capable of holding two passengers, this value is 9000 passengers per hour:

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Peter D. Kauffmann Chapter 1: Introduction to Moving Belts 4

    Up to this point, the logic behind capacity determination for escalators is sound. However, in order to convert this theoretical capacity to practical capacity, the standard approach is to account for loading inefficiencies, thereby reducing the capacity down from this theoretical level. While this approach is backed up by observation and by research, the specific method by which the practical capacity is determined is through a multiplicative adjustment factor, usually 0.8 (ThyssenKrupp Elevator, 2004). By using what in most applications is a constant adjustment factor, the impacts of numerous confounding factors are effectively ignored, from loading delays to luggage to the added space required by walkers as opposed to standers.

    1.3.2.2 Accounting for Regional Differences in Pedestrian Streams

    While it is important to include the impacts of these confounding factors, it is equally important to realize that the desires and characteristics shown by users in different regions are not the same. That is, the speed and aggressiveness parameters that are seen in New York City will be different from those in Newport News, just as the behavior of a rider on an escalator in a transit station during peak hours will be more rushed than a passenger at a shopping mall will on a Tuesday afternoon. It is theorized that if pedestrian behavior could be changed within the context of the capacity model, the results would be applicable over a wider range of sensitivity scenarios. 1.3.2.3 Effects of Crush Loading

    As mentioned above, simulation of pedestrian flows is sometimes used in situations where a sudden inflow of users can raise safety concerns, either through the potential for trampling or crushing or because of the risk of overflowing a limited loading area. To this end, it is suggested that microsimulation of moving walkways may similarly be able to account for the intricacies present under these conditions.

    Under crush loading conditions, microsimulation would, for instance, allow the engineer to track the growth of a queue on a subway platform. If the queue reached some critical length, there may be potential for members of the crowd to fall onto the tracks, so the designer would ensure that this condition would not occur given projected train unloading rates. However, an additional benefit of the use of microsimulation in determining belt capacity would be that various parameters such as the ones discussed above might be implemented in the model. 1.4 Proposed Approach to Belt Capacity Analysis

    Because of the perceived drawbacks present in the current state of the practice in moving belt capacity analysis, this paper proposes the development of a microsimulation framework that describes and quantifies pedestrian flow on moving belt surfaces.

    1.4.1 Model Operation

    This model would be capable of taking in a range of relevant input parameters, from pedestrian desires and choices to belt specifications and operational characteristics. This information would be used to define the simulation environment, at which point a logical framework and rules would be used to govern the interaction of all participants within the system. In this way, all automata within the model will exhibit behaviors based on their own desires within the context of the overall system rules. Through the interaction of every entity, the system-wide characteristics may be tabulated over time to determine relevant operational measures of effectiveness.

Peter D. Kauffmann Chapter 1: Introduction to Moving Belts 5

    1.4.2 Source Data

    In order to adequately define the rules that govern each entity’s behaviors, a literature review

    will be undertaken in order to quantify and codify the choices made by a person in an activity as mundane as walking or stair climbing. As will be seen below, because of the relative lack of research conducted on the specific topics of following and passing behavior while climbing a moving belt, this information will be pulled from a diverse array of fields. While pedestrian behaviors like stair climbing and walking speeds can be taken directly from applicable studies, additional information will be taken from research conducted on walkers within bottlenecks and applied to the constrictions that are present in an escalator.

    1.4.2.1 Inclusion of Automotive Choice Behavior

    Furthermore, to account for the thought process that results in following behaviors and passing choice, information originally developed to model highway driving will be integrated into the model. Although it may seem improper to use automotive following and passing rules to determine the behavior of pedestrians, the means by which these human factors decisions are made are actually very similar by virtue of the fact that in both cases it is a person who is making the choice. Additionally, since these automotive rules are relatively well funded, there exists a much larger and more substantial basis of work on which to base this section of the model. 1.4.2.2 Sensitivity Analysis Capabilities

    Through the use of research from a variety of unconventional sources in a novel approach to moving belt analysis, these unaddressed factors may be included in the transportation analysis and decision-making process. Furthermore, it will be possible to vary the input factors slightly to determine how sensitive the solution is to slight changes in any number of characteristics, from input stream volumes to belt speed to traveler characteristics. In this way, projected changes in passenger mix or operational rules can be investigated and accounted for in addition to increases in passenger volumes.

NOTES TO SELF:

    Revise to include phrase “ambulatory facility” in place of some awkward phrasings.

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