109 results found
Han K, Eve G, Friesz TL, Computing Dynamic User Equilibria on Large-Scale Networks with Software Implementation, Networks and Spatial Economics, ISSN: 1566-113X
Song W, Han K, Wang Y, et al., 2018, Statistical metamodeling of dynamic network loading, 22nd International Symposium on Transportation and Traffic Theory (ISTTT), Publisher: PERGAMON-ELSEVIER SCIENCE LTD, Pages: 740-756, ISSN: 0191-2615
Munoz-Mendez F, Han K, Klemmer K, et al., 2018, Community structures, interactions and dynamics in London's bicycle sharing network, Pages: 1015-1023
© 2018 Copyright is held by the owner/author(s). Publication rights licensed to ACM. We apply a novel clustering technique to London's bikesharing network, deriving distinctive behavioral patterns and assessing community interactions and spatio-temporal dynamics. The analyses reveal self-contained, interconnected and hybrid clusters that mimic London's physical structure. Exploring changes over time, we find geographically isolated and specialized communities to be relatively consistent, while the remaining system exhibits volatility. We increase understanding of the collective behavior of the bikesharing users.
Tian Y, Wan L, Han K, et al., 2018, Optimization of terminal airspace operation with environmental considerations, TRANSPORTATION RESEARCH PART D-TRANSPORT AND ENVIRONMENT, Vol: 63, Pages: 872-889, ISSN: 1361-9209
Yin J, Hu M, Ma Y, et al., 2018, Airport taxi situation awareness with a macroscopic distribution network analysis, Networks and Spatial Economics, ISSN: 1566-113X
This paper proposes a framework for airport taxi situation awareness to enhance the assessment of aircraft ground movements in complex airport surfaces. Through a macroscopic distribution network (MDN) of arrival and departure taxi processes in a spatial-temporal domain, we establish two sets of taxi situation indices (TSIs) from the perspectives of single aircraft and the whole network. These TSIs are characterized into five categories: aircraft taxi time indices (ATTIs), surface instantaneous flow indices (SIFIs), surface cumulative flow indices (SCFIs), aircraft queue length indices (AQLIs), and slot resource demand indices (SRDIs). The coverage of the TSIs system is discussed in detail based on the departure and arrival reference aircraft. A real-world case study of Shanghai Pudong airport demonstrates significant correlations among some of the proposed TSIs such as the ATTIs, SCFIs and AQLIs. We identify the most crucial influencing factors of the taxi process and propose two new metrics to assess the taxi situation at the aircraft and network levels, by establishing taxi situation assessment models instead of using two systems of multiple TSIs. The findings can provide significant references to decision makers regarding airport ground movements for the purposes of air traffic scheduling and congestion control in complex airports.
Fu Z, Jia Q, Chen J, et al., 2018, A fine discrete field cellular automaton for pedestrian dynamics integrating pedestrian heterogeneity, anisotropy, and time-dependent characteristics, TRANSPORTATION RESEARCH PART C-EMERGING TECHNOLOGIES, Vol: 91, Pages: 37-61, ISSN: 0968-090X
Wang Y, Szeto WY, Han K, et al., 2018, Dynamic traffic assignment: A review of the methodological advances for environmentally sustainable road transportation applications, TRANSPORTATION RESEARCH PART B-METHODOLOGICAL, Vol: 111, Pages: 370-394, ISSN: 0191-2615
Sidiropoulos S, Majumdar A, Han K, 2018, A framework for the optimization of terminal airspace operations in Multi-Airport Systems, Transportation Research Part B: Methodological, Vol: 110, Pages: 160-187, ISSN: 0191-2615
Major cities like London, New York, and Tokyo are served by several airports, effectively creating a Multi-Airport System (MAS), or Metroplex. The operations of individual Metroplex airports are highly interdependent, rendering their efficient management rather difficult. This paper proposes a framework for the design of dynamic arrival and departure routes in MAS Terminal Maneuvering Areas, which fundamentally changes the operation in MAS airspaces for much improved efficiency when compared to the current situation. The framework consists of three components. The first presents a new procedure for characterizing dynamic arrival and departure routes based on the spatio-temporal distributions of flights. The second component is a novel Analytic Hierarchy Process (AHP) model for the prioritization of the dynamic routes, which takes into account a set of quantitative and qualitative attributes important for MAS operations. The third component is a priority-based method for the positioning of terminal waypoints as well as the design of three-dimensional, conflict-free terminal routes. Such a method accounts for the AHP-derived priorities while satisfying the minimal separation and aircraft maneuverability constraints. The developed framework is applied to a case study of the New York Metroplex, using aircraft trajectories during a heavy traffic period on typical day of operation in the New York Terminal Control Area in November 2011. The proposed framework is quantitatively assessed using the AirTOp fast-time simulation model. The results suggest significant improvements of the new design over the existing one, as measured by several key performance indicators such as travel distance, travel time, fuel burn, and controller workload. The operational feasibility of the framework is further validated qualitatively by subject matter experts from the Port Authority of New York and New Jersey, the operator of the New York Metroplex.
Han K, Graham D, Ochieng W, 2018, M20/A20 Congestion Prediction with Post-Brexit Border Delays, M20/A20 Congestion Prediction with Post-Brexit Border Delays
This research was commissioned by the BBC Inside Out South East program. It aims to quantify the congestion impact on M20/A20 of potential check time increase at Port of Dover and Eurotunnel (in Folkestone) in a post-Brexit scenario. We focus on a 40-mile segment of the M20/A20 motorway between Maidstone and Dover, with local access to Ashford and Folkestone. We consider outbound lorries and passenger vehicles that use the ferry and tunnel to cross the Straight of Dover, as well as traffic with local origins and destinations. Traffic simulations were conducted with assumptions regarding the check times at Dover and Eurotunnel for both current and post-Brexit scenarios. The impact of vehicle queuing at these locations was assessed in terms of queue length, travel time, and disruption to local traffic. The findings show that even one or two minutes of extra check times at the borders are accompanied by a dramatic increase of congestion on the motorways as well as local streets, with queues extending up to 30 miles from Dover/Eurotunnel towards Maidstone and travel time approaching 5 hours in peak times.
Pu J, Liu C, Zhao J, et al., 2018, Vulnerability Assessment of Metro Systems Based on Dynamic Network Structure, 22nd Pacific-Asia Conference on Knowledge Discovery and Data Mining (PAKDD), Publisher: SPRINGER INTERNATIONAL PUBLISHING AG, Pages: 525-537, ISSN: 0302-9743
Friesz TL, Han K, 2018, The mathematical foundations of dynamic user equilibrium, Transportation Research Part B: Methodological, ISSN: 0191-2615
© 2018 Elsevier Ltd This paper is pedagogic in nature, meant to provide researchers a single reference for learning how to apply the emerging literature on differential variational inequalities to the study of dynamic traffic assignment problems that are Cournot-like noncooperative games. The paper is presented in a style that makes it accessible to the widest possible audience. In particular, we apply the theory of differential variational inequalities (DVIs) to the dynamic user equilibrium (DUE) problem. We first show that there is a variational inequality whose necessary conditions describe a DUE. We restate the flow conservation constraint associated with each origin-destination pair as a first-order two-point boundary value problem, thereby leading to a DVI representation of DUE; then we employ Pontryagin-type necessary conditions to show that any DVI solution is a DUE. We also show that the DVI formulation leads directly to a fixed-point algorithm. We explain the fixed-point algorithm by showing the calculations intrinsic to each of its steps when applied to simple examples.
Yin J, Ma Y, Hu Y, et al., 2018, Dynamic Runway Configurations and Flexible Arrival/Departure Tradeoffs in Metroplex Airports, IEEE/AIAA 37th Digital Avionics Systems Conference (DASC), Publisher: IEEE, Pages: 1176-1183, ISSN: 2155-7195
Yin J, Hu Y, Ma Y, et al., 2018, Machine Learning Techniques for Taxi-out Time Prediction with a Macroscopic Network Topology, IEEE/AIAA 37th Digital Avionics Systems Conference (DASC), Publisher: IEEE, Pages: 713-720, ISSN: 2155-7195
Han K, Friesz TL, 2017, Continuity of the Effective Delay Operator for Networks Based on the Link Delay Model, Networks and Spatial Economics, Vol: 17, Pages: 1095-1110, ISSN: 1566-113X
This paper is concerned with a dynamic traffic network performance model, known as dynamic network loading (DNL), that is frequently employed in the modeling and computation of analytical dynamic user equilibrium (DUE). As a key component of continuous-time DUE models, DNL aims at describing and predicting the spatial-temporal evolution of traffic flows on a network that is consistent with established route and departure time choices of travelers, by introducing appropriate dynamics to flow propagation, flow conservation, and travel delays. The DNL procedure gives rise to the path delay operator, which associates a vector of path flows (path departure rates) with the corresponding path travel costs. In this paper, we establish strong continuity of the path delay operator for networks whose arc flows are described by the link delay model (Friesz et al., Oper Res 41(1):80–91, 1993; Carey, Networks and Spatial Economics 1(3):349–375, 2001). Unlike the result established in Zhu and Marcotte (Transp Sci 34(4):402–414, 2000), our continuity proof is constructed without assuming a priori uniform boundedness of the path flows. Such a more general continuity result has a few important implications to the existence of simultaneous route-and-departure-time DUE without a priori boundedness of path flows, and to any numerical algorithm that allows convergence to be rigorously analyzed.
Han K, Yao T, Jiang C, et al., 2017, Lagrangian-based Hydrodynamic Model for Traffic Data Fusion on Freeways, NETWORKS & SPATIAL ECONOMICS, Vol: 17, Pages: 1071-1094, ISSN: 1566-113X
Yang L, Yin S, Han K, et al., 2017, Fundamental diagrams of airport surface traffic: Models and applications, TRANSPORTATION RESEARCH PART B-METHODOLOGICAL, Vol: 106, Pages: 29-51, ISSN: 0191-2615
Yang L, Yin S, Hu M, et al., 2017, Empirical exploration of air traffic and human dynamics in terminal airspaces, TRANSPORTATION RESEARCH PART C-EMERGING TECHNOLOGIES, Vol: 84, Pages: 219-244, ISSN: 0968-090X
Li S, Xu R, Han K, et al., Optimizing train service plans to coordinate transport capacity for urban rail transit lines, Transportation Research Board 97th Annual Meeting
In view of big passenger flow volume and high passenger risk at transfer stations during the peak period, this paper studied the coordination method of urban rail transit network transportation organization from the perspective of capacity matching. The change law of passenger flow was analyzed, and the calculation methods of train remaining carrying capacity, waiting passenger demand and the largest number of people gathered on the platform were determined. The concept of capacity coordination degree (CCD) was proposed, used to describe the matching degree between traffic demand and transport capacity of each line. Based on this, taking the optimal comprehensive CCD of the transfer station as the goal, the first train departure time and train departure interval as decision variables, and guarantee of passenger safety within station as the main constraint, a nonlinear integer programming model of train service plans collaborative optimization was established, and the genetic algorithm was designed. A case study of a two-line intersecting network was carried out. The results show that, after the use of capacity coordination scheme, the total number of running trains increases by only 1, the number of remaining passengers reduces by 68.44%, comprehensive CCD is closer to 1, and the largest number of people gathered in big passenger flow directions decreases by 11.77% and 19.68%, respectively. Transport supply can better meet the passenger demand in all directions, effectively improving the interests of both passengers and operators.
Ma L, Chen Q, Han K, et al., A tale of two stations: Analyzing metro ridership with big data, Transportation Research Board 97th Annual Meeting
This paper presents a multi-dimensional case study of the Beijing metro system. In particular, we examine two non-transfer stations, Zaoying and Jiangtai, which are on the same metro line in central Beijing. Multi-source and heterogeneous data are integrated to analyze and diagnose the drastically different metro ridership at the two stations. These include transit smart card data, taxi GPS data, network data, Point of Interest data, demographic data, online second-hand property price data, cell phone signalling data, and bike sharing data. The different utilization of metro system at these two locations is attributed to a number of factors pertaining to transportation infrastructure, built environment, demographic composition, commuting patterns, and connectivity of multi-modal transit networks. The findings suggest the importance of local accessibility of the metro stations as well as its connectivity with the rest of the transit system, in order to maximize the transport capability of the metro system. Our analysis also highlights the benefit of collecting and analyzing fine-granularity data in order to identify key bottlenecks and inefficiencies in the transportation system, as conventional macroscopic transportation planning data do not sufficiently capture the local accessibility and mobility in an urban environment.
Chen D, Hu M, Zhang H, et al., 2017, A network based dynamic air traffic flow model for en route airspace system traffic flow optimization, TRANSPORTATION RESEARCH PART E-LOGISTICS AND TRANSPORTATION REVIEW, Vol: 106, Pages: 1-19, ISSN: 1366-5545
Yang L, Yin S, Hu M, et al., Empirical study of air traffic dynamics using coupled network modeling and non-linear analysis, Transportation Research Board 97th Annual Meeting
Yin J, Hu M, Ma Y, et al., Spatial-temporal topology and performance analysis of airport taxi network, Transportation Research Board 97th Annual Meeting
This paper proposes a spatial-temporal topology from a macroscopic view to analyze the performance of airport taxi network operations. Through a macroscopic modelling of arrival and departure aircraft taxi processes in the airport taxi network, we establish a system of taxi network performance indicators (TNPIs) consisting 5 categories and 26 indicators, which includes the surface instantaneous flow indicators (SIFIs), surface cumulative flow indicators (SCFIs), aircraft queue length indicators (AQLIs), slot resource demand indicators (SRDIs) and aircraft taxi time indicators (ATTIs). Then, we analyze the correlation among different TNPIs. By identifying the key factors affecting aircraft taxi time such as takeoff and landing queue length, we provide models for predicting aircraft taxi time based on multiple regression analysis. The real-world case study in Shanghai Pudong airport demonstrates significant correlations among some of the proposed TNPIs, and the results also show the significantly improved accuracy of the proposed prediction models over some conventional models, which brings significant benefits to analyze the performance of airport taxi network and support decision making in airport operations.
Qin F, Sun R, Ochieng WY, et al., 2017, Integrated GNSS/DR/road segment information system for variable road user charging, TRANSPORTATION RESEARCH PART C-EMERGING TECHNOLOGIES, Vol: 82, Pages: 261-272, ISSN: 0968-090X
Song W, Han K, Wang Y, et al., 2017, Statistical metamodeling of dynamic network loading, Transportation Research Part B: Methodological, ISSN: 0191-2615
Yu C, Ma W, Han K, et al., 2017, Optimization of vehicle and pedestrian signals at isolated intersections, TRANSPORTATION RESEARCH PART B-METHODOLOGICAL, Vol: 98, Pages: 135-153, ISSN: 0191-2615
Sidiropoulos S, Han K, Majumdar A, et al., 2017, Robust identification of air traffic flow patterns in Metroplex terminal areas under demand uncertainty, TRANSPORTATION RESEARCH PART C-EMERGING TECHNOLOGIES, Vol: 75, Pages: 212-227, ISSN: 0968-090X
Liu J, Li K, Yin M, et al., 2017, Optimizing Key Parameters of Ground Delay Program with Uncertain Airport Capacity, JOURNAL OF ADVANCED TRANSPORTATION, ISSN: 0197-6729
Han K, 2017, Framework for Real-Time Traffic Management with Case Studies, TRANSPORTATION RESEARCH RECORD, Pages: 35-43, ISSN: 0361-1981
Song W, Han K, Wang Y, et al., 2017, Statistical metamodeling of dynamic network loading, 22nd International Symposium on Transportation and Traffic Theory (ISTTT), Publisher: ELSEVIER SCIENCE BV, Pages: 263-282, ISSN: 2352-1465
Shang W, Han K, Ochieng W, et al., 2017, Agent-based day-to-day traffic network model with information percolation, TRANSPORTMETRICA A-TRANSPORT SCIENCE, Vol: 13, Pages: 38-66, ISSN: 2324-9935
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