A GIS spatial planning model for bus routing

A GIS SPATIAL PLANNING MODEL FOR BUS ROUTING KAMALASUDHAN ACHUTHAN NATIONAL UNIVERSITY OF SINGAPORE 2003 A GIS SPATIAL PLANNING MODEL FOR BUS ROUTING KAMALASUDHAN ACHUTHAN (B.E. (Civil)) A THESIS SUBMITTED FOR THE DEGREE OF MASTER OF ENGINEERING DEPARTMENT OF CIVIL ENGINEERING NATIONAL UNIVERSITY OF SINGAPORE 2003 ACKNOWLEDGEMENTS I am deeply indebted to my supervisor, Associate Professor Chin Hoong Chor for his foresight in giving me the opportunity to develop the model presented here. His invaluable advice, patient guidance, encouragement and exceptional support made working with him a privilege. I express my deep, sincere and heartfelt thanks and gratefulness to him. I would like to express my gratitude and appreciations to my co-supervisor, Dr. Huang Bo for his guidance, helpful suggestions, encouragement and above all friendship support. I wish to express my thanks to the Traffic Laboratory and the staff members Mdm. Theresa and Mdm. Wei Ling for the help and support. I would also like to extend my heartfelt thanks to my colleagues Mr. Kok Wai, Mr. Shakil, Mr. Zhou Jun, Mr.Kumara, and Ms. Sudeshna for their fruitful discussions, suggestions and caring friendship. National University of Singapore i TABLE OF CONTENTS ACKNOWLEDGEMENTS …………………………………………………………. i TABLE OF CONTENTS …………………………………………………………….ii SUMMARY ………………………………………………………………………… vi LIST OF FIGURES ……………………………………………………………… .viii LIST OF TABLES ………………………………………………………………… x LIST OF SYMBOLS…………………………………………………………………xi CHAPTER ONE: INTRODUCTION 1.1 Background …………………………………………………………….1 1.2 Objective and Scope of Study ………………………………………….8 1.3 Organization of the Thesis ……………………………………………. CHAPTER TWO: METHODOLOGY 2.1 Introduction ………………………………………………………… 10 2.2 Model Setup………………………………………………………… .12 2.3 Model Development ……………………………………………….…13 2.4 Model Application ……………………………………………………13 2.5 Summary …………………………………………………………… .14 CHAPTER THREE: MODEL SETUP 3.1 Introduction ………………………………………………………… .15 3.2 Data Models ………………………………………………………… 16 3.2.1 Vector Data Model ………………………………………… 16 National University of Singapore ii Table of Contents 3.2.2 Raster Data Model ……………………………………………16 3.2.3 Digital Elevation Model ………………………………………17 3.2.4 Network Model ……………………………………………….18 3.2.5 Combination of Models……………………………………….18 3.3 Software for GIS …………………………………………………… .19 3.4 GIS Database …………………………………………………………20 3.4.1 Data Needs for the Study …………………………………… 21 3.4.2 Man-made Aspects ………………………………………… .22 3.4.3 Natural Aspects ……………………………………………….22 3.5 Study Area ………………………………………………………… 22 3.6 Road Centerline ………………………………………………………24 3.7 Transit Ridership …………………………………………………… .25 3.8 Creating Surface Models and Calculating Slope …………………… 26 3.8.1 Factors Influencing Slope …………………………………….28 3.9 Cost Surface Modeling ……………………………………………….31 3.9.1 GIS Models ………………………………………………… .31 3.9.2 Index Models …………………………………………………32 3.10 Summary …………………………………………………………… .39 CHAPTER FOUR: MODEL DEVELOPMENT 4.1 Introduction ………………………………………………………… .40 4.2 Model Overview …………………………………………………… .41 4.3 Development of Accessibility Contours …………………………… 42 4.3.1 Cost Weighted Distance Mapping ……………………………43 4.4 Link Ridership Determination ……………………………………… 49 National University of Singapore iii Table of Contents 4.4.1 Multinomial Logit Model …………………………………….50 4.4.2 Integration of the Model into GIS ……………………………51 4.5 Model Behavior ………………………………………………………53 4.6 Bus Routing ………………………………………………………… 59 4.7 Summary …………………………………………………………… .66 CHAPTER FIVE: MODEL APPLICATION 5.1 Introduction ………………………………………………………… .67 5.2 Application Area …………………………………………………… .67 5.3 Planning Parameters ………………………………………………….70 5.3.1 Road Network ……………………………………………… .70 5.3.2 Land Use …………………………………………………… .70 5.3.3 Natural Terrain ……………………………………………… 71 5.3.4 Population …………………………………………………….71 5.4 Model Implementation and Results ………………………………… 72 5.4.1 Input Data …………………………………………………….72 5.4.2 Cost Surface ………………………………………………… 74 5.4.3 Link Ridership ……………………………………………… 74 5.4.4 Bus Route …………………………………………………… 76 5.5 Alternative Scenarios …………………………………………………78 5.5.1 Scenario 1: Land use changes ……………………………… .78 5.5.2 Scenario 2: Road layout changes …………………………… 81 5.6 Summary …………………………………………………………… .84 National University of Singapore iv Table of Contents CHAPTER SIX: CONCLUSIONS 6.1 Conclusions ………………………………………………………… 85 6.2 Recommendations …………………………………………………….87 REFERENCES……………………………………………………………………….89 National University of Singapore v SUMMARY The planning of transit routes requires understanding demographics, land use and travel patterns of an area. The dynamic nature of these systems necessitates regular review and analysis to ensure that the transit system continues to meets the needs of the population it serves. Geographic Information Systems (GIS) provide a flexible framework for planning and analyzing transit routes. Demographic, housing, land use and infrastructure data may be modeled in a GIS to identify efficient and effective corridors in which to locate routes. However, GIS capabilities are not fully utilized in the planning of transits. Part of the route location and analysis problem requires estimating the population in the service area of a route to determine the ridership. A route’s service area is defined using walking distance or travel time and indicates the route’s accessibility to the public. It is based on this estimation of the ridership that transit routes are designed. Previous methods consider only distance as the measure of accessibility. However, there are some other factors that affect the accessibility of the pedestrians in reaching transit routes such as natural barriers like the slope or gradient of the earth surface, man-made barriers like the community walls etc. Hence, in this study a GIS spatial planning model is developed which can take into consideration the above factors that affect accessibility and better estimate the ridership arriving at routes. Using this estimation the model also designs a bus route which is optimal from both users and operators point of view. National University of Singapore vi Summary The study consists of three principal phases. Phase One is to identify the data needed for the above application and to setup the GIS database. Using the database the cost surface, which represents the cost of traveling, is modeled for the study area. In Phase Two the model to determine link ridership and design bus routes is developed using GIS spatial functions. The model development stage includes the illustration of the model behavior for various factors. In the last phase, the model is applied and tested in a real world area that presents scenarios because of the dynamic nature of land use and infrastructure. This includes estimation of ridership and design of bus routes for changes in land use and road layout. National University of Singapore vii LIST OF FIGURES Figure 1.1 Bus Planning Process Figure 2.1 Overview of the development of the GIS spatial planning model 11 Figure 3.1 Study area map with GIS layers 23 Figure 3.2 TIN surface modeled for the study area 26 Figure 3.3 Slope map of the study area 28 Figure 3.4 Horn’s Algorithm for computing slope 29 Figure 3.5 Cost surface modeling 37 Figure 3.6 Cost surface modeled for the study area 38 Figure 4.1 Overview of the determination of link ridership 41 Figure 4.2 Iterative algorithm of cost distance mapping 45 Figure 4.3 Cost distance mapping 47 Figure 4.4 Accessibility contour mapped for a building 48 Figure 4.5 Case 1: Straight distance contour mapped for a building 54 Figure 4.6 Case 2: Cost surface and accessibility contour mapped for a building 54 Figure 4.7 Case 3: Cost surface and accessibility contour mapped for a building 56 Figure 4.8 Case 4: Cost surface and accessibility contour mapped for a building 56 Figure 4.9 Link ridership distribution for cases 1-4 58 Figure 4.10 Flowchart for bus routing 62 Figure 4.11 Iteration 1: Transit route designed for study area 64 Figure 4.12 Iteration 2: Transit route designed for study area 65 Figure 4.13 Iteration 3: Transit route designed for study area 65 Figure 5.1 Layout map of National University of Singapore campus 68 Figure 5.2 GIS data layers prepared for NUS 73 National University of Singapore viii Chapter Five: Model Application 5.6 Summary This chapter demonstrates the potential of the model in applying it to a real world area. Firstly, the model is able to determine the probable ridership arriving at various links considering the effects of natural and man-made aspects affecting the pedestrian accessibility in that area. Secondly, it has been shown that the model is able to design efficient bus routes. Thirdly, the model is used to study some of the altering scenarios of the application area by determining the link ridership distribution and the bus route alignments for easier accessibility of users and reduced cost of operators. National University Of Singapore 84 CHAPTER SIX CONCLUSIONS 6.1 Conclusions The need for an optimal transit route planning, considering the impacts of natural and man-made aspects that affect transit route accessibility, calls for the development of a GIS Spatial Planning Model. Not only a GIS model has been successfully developed in the course of the study, the use of the model in enhancing the transit route planning process is illustrated. New functionalities of GIS have been explored in the development of the model to simulate real world conditions. More importantly, the influence of factors affecting accessibility of the pedestrians to bus routes is examined carefully in the modeling process such that any changes in them are easily reflected in the final design of bus routes. The model has taken into account both natural aspects and man-made aspects that affect transit accessibility. For natural aspects, the gradient of the natural terrain has been considered and clearly studied for its influence, whereas for man-made aspects the built up structures such as buildings, building linkages have been considered. Ridership from each building is used to estimate the demand at routes. The disaggregate approach of ridership estimation is a better method as changes in the population can be reflected in the model. This is particularly important in future land use planning and for estimating the demand at various routes and thus for the planning of bus routes. National University of Singapore 85 Chapter Six: Conclusions Unlike the other accessibility measures in transit route planning studies where the service area population is calculated from the routes and just based on distance, the model developed in this study determine the riders from each building arriving to various routes taking into account the spatial factors affecting accessibility, including the distance leading to routes. Thus, the model takes into account the whole of the population in the area considered and the spatial barriers in the planning of bus routes. In the study, the distribution of ridership from each building is based on the mapping of accessibility contours for a maximum walking time considered. The accessibility contours takes the influence of factors affecting accessibility and maps contours of varying accessibility values. Based on these values, the probable ridership is calculated for each route that fall within these contours using an integrated MNL model. Hence, choices made by the riders in selecting routes of equal accessibility and varying accessibility values are incorporated into the model. This will help to plan better bus routes as the ridership determination includes a choice parameter, which can be varied and studied for changes. The route designed by the model works based on the principle that the final route alignment will be the one that can be accessed by the whole population in a certain period of walking time for the area considered. Increasing the walking time to reach the bus routes could well shorten the route length designed. Thus, the model is flexible enough in taking into, both the user and operator constraints in designing transit routes. The model is also tested for its usefulness by applying the model for planning a shuttle bus route for the National University of Singapore Campus. With this model, National University of Singapore 86 Chapter Six: Conclusions alternative scenarios can also be easily evaluated as part of future planning studies. Configuration of bus routes for land use and road layout changes can be studied and assessed. The successful development of the GIS Spatial Planning Model will go a long way in the enhancement of transit route planning and analysis problems, to ensure that the bus routes planned will have improved accessibility to people. 6.2 Recommendations The model can further be improved by developing and integrating a transit ridership forecasting model, which can estimate ridership based on the building characteristics. The MNL model can also be improved by introducing one or more additional variables in calculating the probable ridership. A suitable variable that could be used is the characteristics of the building population, i.e. the building may be residential, office, or a shopping and so the population in them may have certain preferences. This will better estimate the choice of people in choosing bus routes. The cost surface modeled could be improved by considering other unaccounted factors such as, the traffic condition on routes (congestion and safety), environmental conditions of areas (pollution and noise), desirable walking conditions (safety, scenic, protection from adverse weathers) and other specific factors of importance to the study area that may have an effect on the accessibility of commuters. The inclusion of such factors will further improve the ridership estimation. Further, the accessibility contours are mapped for a fixed walking time for all the riders in a building. Future works may be carried out to make this flexible in handling a certain percentage of population with shorter walking times while the rest with longer walking times. National University of Singapore 87 Chapter Six: Conclusions There are also some complementary studies worth considering. The ridership distribution arrived at various links provides necessary information for the positioning of bus stops. With the bus route designed and bus stops located, frequencies can be set and the route can further be analyzed and altered for operator constraints of fleet availability. Though each of these issues may call for a more detailed analysis of the route designed, the model will function as the first step in transit route planning. National University of Singapore 88 REFERENCES Anderson, L.D. Applying Geographic Information Systems to Transportation Planning. Transportation Research Record 1305, pp. 113-117. 1991. Azar, K.T. and Ferreira, J. 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National University of Singapore 99 [...]... of the Geographic Information Systems (GIS) By definition, a GIS is a computerized database management system for the capture, storage, retrieval analysis, and display of spatial data” All elements in the database are referenced to the same geographic coordinate system that permits the spatial analysis of the data The enhancement that GIS can produce in transportation and transportation planning by... 8.2-ArcInfo has been chosen for this study National University of Singapore 19 Chapter Three: Model Setup 3.4 GIS Database GIS capabilities depend upon the way the database has been organised (Kroenke, 1995; Healey, 1991; NCGIA, 1990) GIS database contains two main types of data There are in fact two databases: a spatial database, containing locational data and describing the geography of earth surface... of analytical tools for all the data models It supports an extensive array of data sources, display, and outputs Using Visual Basic for Application (VBA), which is embedded within the software, customized applications can also be developed In addition, it offers many spatial analytical functions for raster data that are not available with other software Considering the above factors, ESRI’s ARCGIS... surface features (shape, position), and an attribute database, containing characteristics of the spatial features The Spatial Database The information contained in the spatial database is held in the form of digital coordinates, which describe the spatial features These can be points (for example, bus stops), lines (for example, roads), or polygons (for example, buildings) The different sets of data will... using GIS (Peng, 1997; Smith, 2000) Hence, GIS have been utilized for maintaining database, planning, and management of transits (Barua et al., 2001;Chen, 1998; Crowson et al., 1997; Koncz and Greenfeld, 1995; Trepanier and Chapleau, 2001) GIS applications for transit analysis have been mainly on ridership forecasting, service planning and market analysis (CUTR, 2001) Service area analysis estimates... population and land use Land use and demographic information are available at disaggregate geography levels: however for transportation analysis purposes they were aggregated to traffic analyses zones (TAZs) TAZs were assumed homogeneous; the socioeconomic and land use variations that exists within the zone are collapsed to an average zonal number without any variance to these attributes Another critical factor... of Singapore 15 Chapter Three: Model Setup 3.2 Data Models Spatial information in two dimensional real world can be presented in two ways: as vector data in the form of points, lines and areas (polygons) or as raster data in the form of uniform systematic organized cells Hence, these form the basic data models of GIS Several other data models used in GIS can extend the representation of a real world... these formats Most of the data needed are for the representation of the real world and hence the accuracy and quality of the data input will have a great influence on the model With the absence of established GIS modeling approaches, this phase is critical for the model that aims to improve access to transit services In addition to the description of data models available in GIS, this chapter also presents... contours and the population data of the buildings as they are the primary inputs for the model The centerline of the road needs to be coded from the road layer for GIS routing functions For cost surface modeling, the aspects of man-made and natural factors affecting accessibility are to be represented as a GIS layer The terrain surface is generated using spatial analysis tools of GIS with the contour layer... requirements of GIS software and an overview of ArcGIS 8.2 that is used in the study The data needs for this study and their required formats, data conversions and preparations to set up the GIS database are also explained The last part describes the process of cost surface modeling using GIS models, which forms the primary input of the spatial planning model that is developed in this study National University . that of the Geographic Information Systems (GIS) . By definition, a GIS is a computerized database management system for the capture, storage, retrieval analysis, and display of spatial data” GIS spatial analysis tools are used to create a buffer zone around transit routes and based on the percentage of spatial unit of analysis area, usually in terms of traffic analysis zones and. use and demographic information are available at disaggregate geography levels: however for transportation analysis purposes they were aggregated to traffic analyses zones (TAZs). TAZs were assumed