Browsing by Author "Xie, Feng"
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Item Beyond Business as Usual: Ensuring the Network We Want Is the Network We Get(2006-09-01) Levinson, David M; de Oca, Norah Montes; Xie, FengThis research, extending the Mn/DOT-funded project If They Come, Will You Build It, assesses the implications of existing trends on future network construction. It compares forecast networks (using models estimated on historical decisions developed with previous research) under alternative budget scenarios (trend, above trend, below trend), with networks constructed according to alternative sets of decision rules developed with Mn/DOT and Metropolitan Council staff. The comparison evaluates alternative futures using a set of performance measures to determine whether the network we would get in the absence of a change in policies (allowing historical policies to go forward) outperforms or underperforms the networks developed by applying suggested decision rules. This evaluation methodology enables new decision rules for network construction (building new links or widening existing links) to be tested. The research suggests a path beyond ?business as usual?.This research incorporates results from the different scenarios tested. It presents the processes, approaches and development to encode historical decision rules. After analyzing flowcharts developed from the interviews of staff at different levels of government, if-then rules are generated for each jurisdiction. This research then describes the details and processes necessary to run the network forecasting models with various decision rules. Results for different scenarios are presented including adding additional constraints for the transportation network expansion and calibration process details. A comparison and analysis between scenarios is made in order to provide a final conclusion on what scenario will produce the greatest benefit for the Twin Cities Metropolitan Area Transportation Network.
Item The Co-Evolution of Land Use and Road Networks(Emerald Group, 2007) Levinson, David M; Xie, Feng; Zhu, ShanjiangItem Does first last? The existence and extent of first mover advantages on spatial networks(Journal of Transport and Land Use, 2011) Levinson, David; Xie, FengThis paper examines the nature of first-mover advantages in the deployment of spatially differentiated surface transport networks. A number of factors explaining the existence of first-mover advantages have been identified in the literature; however, the questions of whether these factors exist in spatial networks, and of how they play out with true capital immobility have remained unanswered. By examining empirical examples of commuter rail and the Underground in London, first-mover advantage is observed and its sources explored. A model of network diffusion is then constructed to replicate the growth of surface transport networks, making it possible to analyze first-mover advantage in a controlled environment. Simulation experiments are conducted, and Spearman rank correlation tests reveal that first-mover advantages can exist in a surface transport network and can become increasingly prominent as the network expands. In addition, the analysis discloses that the extent of first-mover advantages may relate to the initial land use distribution and network redundancy. The sensitivity of simulation results to model parameters are also examined.Item Does First Last? The existence and extent of first mover advantages on spatial networks.(University of Minnesota, 2011) Levinson, David M; Xie, FengThis paper examines the nature of first mover advantages in the deployment of spatially-differentiated surface transport networks. The literature on first mover advantages identifies a number of sources that explain their existence. However whether those sources exist in spatial networks, and how they play out with true capital immobility have been unanswered questions. By examining the empirical examples of commuter rail and the Underground in London, first mover advantage was observed and its sources explored. A model of network diffusion was then constructed to replicate the growth of surface transport networks, which enables first mover advantage to be analyzed in a controlled environment. Simulation experiments are conducted and Spearman rank correlation tests revealed that first mover advantages can exist in a surface transport network and become increasingly prominent as the network expands. In addition, the analysis discloses that the extent of first mover advantages may relate to the initial land use distribution and network redundancy. The sensitivity of simulation results to model parameters are also examined.Item Enhancing Transportation Education through On-line Simulation using an Agent-Based Demand and Assignment Model(American Society of Civil Engineers, 2011) Zhu, Shanjiang; Xie, Feng; Levinson, David MThis research explores the effectiveness of using simulation as a tool for enhancing classroom learning in the Civil Engineering Department of the University of Minnesota at Twin Cities. The authors developed a modern transportation planning software package, Agent-based Demand and Assignment Model (ADAM), that is consistent with our present understanding of travel behavior, that is platform independent, and that is easy to learn and is thus usable by students. An in-class project incorporated ADAM and the performance of this education strategy was evaluated through pre-class survey, post-class survey, scores in the quiz focusing on travel demand modeling and final scores. Results showed that ADAM effectively enhanced students' self-reported understanding of transportation planning and their skills of forming opinions, evaluating projects and making judgments. Students of some learning styles were found to benefit more than others through simulation-based teaching strategy. Findings in this research could have significant implications for future practice of simulation-based teaching strategy.Item Evaluating the Effects of I-35W Bridge Collapse on Road-Users in the Twin Cities Metropolitan Region.(Taylor and Francis, 2011) Xie, FengThis study evaluates the effects of I-35W bridge collapse on road-users in the Minneapolis-St. Paul Metropolitan area. We adopted the seven-County travel demand model developed in previous research, re-calibrated it against July 2007 loop detector traffic data, and used this model to carry out an evaluation of economic loss incurred by increased travel delay in alternative scenarios before and after the bridge collapse. We concluded that the failure of the I-35W bridge resulted in an economic loss of $71,000 to $220,000 a day, depending on how flexible road-users in the system can adjust their trip destinations in response to the bridge closing. We also estimated that the major traffic restoration projects Mn/DOT has implemented in quick response to the bridge collapse can save road-users $9,500 to $17,500 a day. This translates into a benefit-cost ratio of 2.0-9.0, suggesting these projects are highly beneficiary in an economic sense. In this analysis,the use of a simplified, scaled-down travel demand model enabled us to carry out the analysis quickly and accurately, showing its contributions in transportation planning under situations such as emergency relief and comprehensive design.Item Evolution of the Second-Story City: The Minneapolis Skyway System(Pion, 2009) Corbett, Michael; Xie, Feng; Levinson, David MThis paper describes and explains the growth of the Minneapolis Skyway network. Accessibility is used as a major factor in understanding that growth (i.e. does the network connect to the location(s) with the highest accessibility, followed by the second highest, and so on). First, employment opportunities are used as the measure of activity and are based off of the square footage of buildings and/or ITE trip generation rates. Using information about the buildings located downtown for each year since the first skyway was built, the accessibilities of each of the connected and adjacent unconnected blocks were calculated for every time period the skyway system expanded. The purpose is to determine how often the expansion connected the block with the highest accessibility. The results show that though important, accessibility was rarely maximized, except in the early stages of development. A connect-choice logit model relating the probability of joining the network (in a given year) to accessibility and network size was employed. The results show accessibility does remain an important factor in predicting which links are connected. Physical difficulties in making connections may have played a role, as well as the potential for adverse economic impacts.Item Forecasting and Evaluating Network Growth.(2012) Levinson, David M; Xie, Feng; Montes de Oca, NorahThis research assesses the implications of existing trends on future network investment, comparing alternative scenarios concerning budgets and investment rules across a variety of performance measures. The main scenarios compare 'stated decision rules', processes encoded in flowcharts and weights developed from official documents or by discussion with agency staff, with 'revealed decision rules', weights estimated statistically based on observed historical behavior. This research specifies the processes necessary to run the network forecasting models with various decision rules. Results for different scenarios are presented including adding additional constraints for the transportation network expansion and calibration process details. We find that alternative decision rules make only small differences in overall system performance, though they direct investments to very different locations. However, changes in total budget can make a significant difference to system-wide performance.Item Governance Choice on a Serial Network(2009) Xie, Feng; Levinson, David MThis paper analyzes governance choice in a two-level federation in providing road infrastructure across jurisdictions. Two models are proposed to predict the choice of centralized or decentralized spending structure on a serial road network shared by two districts. While the first model considers simple Pigouvian behavior of governments, the second explicitly models political forces at both a local and central level. Both models led to the conclusions that the spending structure is chosen based on a satisfactory comprise between benefits and costs associated with alternative decision-making processes, and that governance choice may spontaneously shift as the infrastructure improves temporally.Item How Streetcars Shaped Suburbanization: A Granger-Causality Analysis of Land Use and Transit in The Twin Cities.(Oxford University Press, 2010) Xie, Feng; Levinson, David MThis paper presents a causality analysis of the coupled development of population and streetcars in the Twin Cities metropolitan area. Historic residence and network data were assembled for 1900-1930, and linear cross-sectional time-series models were estimated at both a tract and block level using this data. It is found that, in contrast with transportation systems that were expanded in response to increased demand, the rapid expansion of the streetcar system during the electric era has been driven by other forces and to a large extent led land development in the Twin Cities. The main forces that have driven this process include technological superiority, monopoly, close connections with real estate business, and people’s reliance on the streetcar for mobility. Proximity to the streetcar is found to be a crucial factor that determines the distribution and development of residences: it is observed that residential density declines with the distance from streetcar lines, and significantly drops beyond a walkable distance; it is also observed that gaining a closer access to streetcar lines within 800 meters (about a half mile) predicts the increase in residential density to a significant extent.Item Illusion of Motion: Variation in Travel Time under Different Driving Conditions(Transportation Research Board, 2009) Zhang, Lei; Xie, Feng; Levinson, David MThis paper explores drivers' subjective value of time under moving and stopped freeway travel conditions using a stated preference survey. Unlike previous studies that assume a constant value of time, this research relates perceived satisfaction of a freeway trip to its quality indicators. Sixty-nine subjects in the Twin Cities are asked in the survey to rank sixteen driving scenarios in four condition sets with different durations of ramp wait and freeway travel. Several utility functions are specified where the weight of ramp delay is a function of the length of the delay itself and subject specific variables, and the resulting choice models estimated using rank-ordered logit and binary logit techniques. Results suggest that drivers perceive ramp wait as more onerous than freeway travel. Drivers also weight each minute of ramp wait more heavily as the length of the delay gets longer. Although the subjects show some tolerance to the first several minutes of ramp delay (less than 5 minutes), they perceive long delays as much as twelve times more onerous than time in motion. The derived weighting function for ramp wait can improve the design of freeway traffic control strategies that trade-off freeway delay with ramp wait. The findings also enable a more utility-based approach for freeway operations than the current method which has the engineering efficiency objective of minimizing total system delay or maximizing throughput. Minimizing total perceived travel time is probably more appropriate than minimizing total absolute travel time which does not take into account driver acceptance. The weighting function can also be easily transformed into a value of time function for project evaluation purposes.Item Jurisdictional Control and Network Growth(2009) Xie, Feng; Levinson, David MTransport infrastructure evolves over time in a complex process as part of a dynamic and open system including travel demand, land use, as well as economic and political initiatives. As transport infrastructure changes, each traveler may adopt a new schedule, frequency, destination, mode, and/or route, and in the long term may change the location of their activities. These new behaviors create demand for a new round of modifications of infrastructure. In the long run, we observe the collective change in the capacity, service, connectivity, and connection patterns (topology) of networks. This paper examines how a fixed set of places incrementally gets connected as transport networks are constructed and upgraded over time. A Simulator Of Network Incremental Connection (SONIC) is constructed to model the process of incremental connections and examines how networks evolve differently under centralized versus decentralized jurisdictional initiatives. Exploring the mechanism underlying this dynamic process can answer questions such as how urban networks have developed into various topologies, which network patterns are more efficient, and whether and how transport engineers, planners, and decision makers can guide the dynamics of land uses and infrastructure in a desired direction.Item Measuring the Structure of Road Networks(The Ohio State University, 2007) Xie, Feng; Levinson, David MSpatial networks display both topologic and geometric variations in their structure. This study investigates the measurement of road network structure. Existing measures of heterogeneity, connectivity, accessibility, and interconnectivity are reviewed and three supplemental measures are proposed, including measures of entropy, connection patterns, and continuity. Proposed measures were applied to 16 test networks, which were derived from 4 idealized base networks: 90-degree, 45-degree, 30-degree, and completely connected. The results show that the differentiated structures of road networks can be evaluated by the measure of entropy; predefined connection patterns of arterial roads can be identified and quantified by the measures of ringness, webness, beltness, circuitness, and treeness. A measure of continuity evaluates the quality of a network from the perspective of travelers. Proposed measures could be used to describe the structural attributes of complicated road networks quantitatively, to compare different network structures, and to explore the structural evolution of networks in the spatial and temporal context. These measures can find their applications in urban planning and transportation practice.Item Modeling the Growth of Transportation Networks: A comprehensive review(Springer, 2009) Xie, Feng; Levinson, David MThis paper reviews the progress that has been made over the last half-century in modeling and analyzing the growth of transportation networks. An overview of studies has been provided following five main streams: network growth in transport geography; traffic flow, transportation planning, and network growth; statistical analyses of network growth; economics of network growth; and network science. In recognition of the vast advances through decades in terms of explor- ing underlying growth mechanisms and developing effective network growth models, the authors also point out the challenges that are faced to model the complex process of transport development.Item Network and Land Use Data for "Indiana Interurban Networks"(2016-07-13) Xie, Feng; Levinson, David M; dlevinson@umn.edu; Levinson, David M; University of Minnesota Nexus Research GroupThis dataset contains the network and land use data for our Indiana Interurban study published as Chapter five "Indiana Interurban Networks" in the book titled "Evolving Transportation Networks" (published by Springer in 2011). The first tab contains a list of stations included in our model and their x/y coordinates. The second has a list of links with their start and end nodes (Station IDs), their open/close years, and Operator ID. The third documents a list of Operators and their IDs. The fourth has a list of counties in Indiana, the x/y coordinates of their centroids, and historical population data from 1897 to 1941. Historical data are only available by decade at the county level, and we calculated years in between by interpolation. the last tab has a list of tracts, the x/y of their centroids, and historical population data from 1897 to 1941 (tract population is approximated assuming population in a county is evenly distributed within county boundary).Item Network growth and ownership organization.(2008-12) Xie, FengThis dissertation explores transportation development and models the evolutionary growth of transportation networks including its determining factors. In particular, it examines the organization of ownership in the provision of transportation infrastructure as a pivotal driving factor. A series of stand-alone studies is dedicated to a comprehensive examination of network growth and ownership structure from different approaches analytically, empirically, and in simulation. The analytical model presents a game-theoretic analysis of centralized versus decentralized governance choice on a serial road network. It reveals that, depending on the tradeoff between the benefits and costs associated with alternative decision-making processes, governance choice reflects constituents' collective spending preferences on infrastructure, and may spontaneously shift as the network improves over time. Empirical studies on Minneapolis skyways and Indiana Interurbans examine the expansion of transportation networks as a discrete sequence of link additions over time. Both studies suggest that the deployment of a network has to some extent followed a predictable path by which accessibility is maximized. Depending on its ownership organization, though, supply decisions may be made under different interests to serve different groups of people. In contrast, the third empirical study, analyzing the causation effects in the coupled development of residences and streetcars in the Twin Cities of Minneapolis and Saint Paul, reveals that the rapid extension of streetcar lines, rather than responding to the demand, preceded residential development along the lines. Integrating findings from analytical and empirical studies, simulation models implement the incremental deployment of a road network under centralized versus decentralized jurisdictional control. Simulation experiments demonstrate the models' capability in terms of assisting planners and decision-makers to test, evaluate, and manage network growth under alternative economic and regulatory regimes. Findings from throughout the dissertation suggest that, the growth of transportation networks can be best described as a complex evolutionary process that is profoundly driven by their ownership organization. Out of all the complexities, this research manages to demonstrate that network growth is following a path that is not only logical in retrospect, but also predictable and manageable from a planning perspective.Item Review of Streets and Patterns by Stephen Marshall(2006) Xie, Feng; Levinson, David MStreets and Patterns. By Stephen Marshall. (London and New York: Spon Press, 2005). [Pp. 312.] $ 69.95. ISBN 0415317509. Stephen Marshall’s Streets and Patterns covers ten years of research into the inter- relationship between transport, streets, and urban patterns, which has been the focus of multiple professions including urban planning, architecture, geography, and transport engineering. This book aims to explore how to reconcile the motor traffic with a neo- traditional system of urban design, emphasizing on streets and their patterns.Item SIGNAL : System of Integrated Growth of Networks and Land Use(2016-07-13) Xie, Feng; Zhu, Shanjiang; Levinson, David M; dlevinson@umn.edu; Levinson, David M; University of Minnesota Nexus Research GroupThis software models the co-evolution of land use and transportation network as a bottom-up process by which re-location of activities and expansion of roads are driven by interdependent decisions of individual businesses, workers, and road owners according to simple decision rules. A Simulator of Integrated Growth of Networks And Land-use (SIGNAL) is developed to implement these decentralized decision making processes, in which the Gini index and equivalent radius were computed to describe and track down the spatial patterns of space and network.Item SONG 2 - Simulator of Network Growth version 2(2016-07-13) Xie, Feng; Levinson, David M; dlevinson@umn.edu; Levinson, David M; University of Minnesota Nexus Research GroupSoftware used in the project Beyond Business as Usual (MnDOT MN/RC-2006-36) This research, extending the Mn/DOT-funded project If They Come, Will You Build It, assesses the implications of existing trends on future network construction. It compares forecast networks (using models estimated on historical decisions developed with previous research) under alternative budget scenarios (trend, above trend, below trend), with networks constructed according to alternative sets of decision rules developed with Mn/DOT and Metropolitan Council staff. The comparison evaluates alternative futures using a set of performance measures to determine whether the network we would get in the absence of a change in policies (allowing historical policies to go forward) outperforms or underperforms the networks developed by applying suggested decision rules. This evaluation methodology enables new decision rules for network construction (building new links or widening existing links) to be tested. The research suggests a path beyond “business as usual”. This research incorporates results from the different scenarios tested. It presents the processes, approaches and development to encode historical decision rules. After analyzing flowcharts developed from the interviews of staff at different levels of government, if-then rules are generated for each jurisdiction. This research then describes the details and processes necessary to run the network forecasting models with various decision rules. Results for different scenarios are presented including adding additional constraints for the transportation network expansion and calibration process details. A comparison and analysis between scenarios is made in order to provide a final conclusion on what scenario will produce the greatest benefit for the Twin Cities Metropolitan Area Transportation Network.Item SONIC - System of Network Incremental Connections(2016-07-13) Xie, Feng; Levinson, David M; dlevinson@umn.edu; Levinson, David M; University of Minnesota Nexus Research GroupThe software contains a network-growth simulation model. The logic is based on the strongest-link assumption (ie for a link to be constructed, it must be ranked the highest in terms of increasing accessibility between the two blocks it connects).