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, Sun, Lijun, Erath, Alexander, 2015 >>
Author(s): Sun, Lijun, Erath, Alexander
Title: A Bayesian network approach for population synthesis
Abstract: Agent-based micro-simulation models require a complete list of agents with detailed demographic/socioeconomic information for the purpose of behavior modeling and simulation. This paper introduces a new alternative for population synthesis based on Bayesian networks. A Bayesian network is a graphical representation of a joint probability distribution, encoding probabilistic relationships among a set of variables in an efficient way. Similar to the previously developed simulation-based approach, in this paper, we consider the population synthesis problem to be the inference of a joint probability distribution. In this sense, the Bayesian network model becomes a perfect tool that allows us to compactly represent/reproduce the structure of the population system and preserve privacy and confidentiality in the meanwhile. We demonstrate and assess the performance of this approach in generating synthetic population for Singapore, by using the Household Interview Travel Survey (HITS) data as the known test population. Our results show that the introduced Bayesian network approach is powerful in characterizing the underlying joint distribution, and meanwhile the overfitting of data can be avoided as much as possible.2
Published in: Transportation research. Part C
Volume: 61
Pages: 49 - 62
ISSN: 0968-090X
Publication date / Date received: 2015-12-01
Publication status: Oxford
Publication status: Published
Subjects: Population synthesis, Agent-based model, Bayesian networks, Data-driven
Language: English
Keyword: Population synthesis, Agent-based model, Bayesian networks, Data-driven
DBID source: FORM-1434811890
DOI: 10.1016/j.trc.2015.10.010
Nebis system number: 000889058
, Jin, Jian Gang, Lu, Linjun, Sun, Lijun, Yin, Jingbo, 2015 >>
Author(s): Jin, Jian Gang, Lu, Linjun, Sun, Lijun, Yin, Jingbo
Title: Optimal allocation of protective resources in urban rail transit networks against intentional attacks
Abstract: This paper advances the field of network interdiction analysis by introducing an application to the urban rail transit network, deploying protective resources against intentional attacks. The resource allocation problem for urban rail transit systems is considered as a game between two players, the attacker interdicting certain rail stations to generate greatest disruption impact and the system defender fortifying the network to maximize the system's robustness to external interdictions. This paper introduces a game-theoretic approach for enhancing urban transit networks' robustness to intentional disruptions via optimally allocating protection resources. A tri-level defender–attacker–user game-theoretic model is developed to allocate protective resources among rail stations in the rail transit network. This paper is distinguished with previous studies in that more sophisticated interdiction behaviors by the attacker, such as coordinated attack on multiple locations and various attacking intensities, are specifically considered. Besides, a more complex multi-commodity network flow model is employed to model the commuter travel pattern in the degraded rail network after interdiction. An effective nested variable neighborhood search method is devised to obtain the solution to the game in an efficient manner. A case study based on the Singapore rail transit system and actual travel demand data is finally carried out to assess the protective resources' effectiveness against intentional attacks.2
Published in: Transportation Research. Part E, Logistics and Transportation Review
Volume: 84
Pages: 73 - 87
ISSN: 1366-5545
Publication date / Date received: 2015-12-01
Publication status: Amsterdam
Publication status: Published
Subjects: Verkehr und Transport|Traffic and Transportation, Urban rail transit, Public transport, Network interdiction, Multilevel programming, Resource allocation
Language: English
Keyword: Urban rail transit, Public transport, Network interdiction, Multilevel programming, Resource allocation
DBID source: FORM-1448477225
DOI: 10.1016/j.tre.2015.10.008
Nebis system number: 004141982
, Sun, Lijun, Lu, Y., Jin, Jian Gang, Lee, Der-Horng, Axhausen, Kay W., 2015 >>
Author(s): Sun, Lijun, Lu, Y., Jin, Jian Gang, Lee, Der-Horng, Axhausen, Kay W.
Title: An integrated Bayesian Approach for passenger flow assignment in metro network
Abstract: This paper proposes an integrated Bayesian statistical inference framework to characterize passenger flow assignment model in a complex metro network. In doing so, we combine network cost attribute estimation and passenger route choice modeling using Bayesian inference. We build the posterior density by taking the likelihood of observing passenger travel times provided by smart card data and our prior knowledge about the studied metro network. Given the high-dimensional nature of parameters in this framework, we apply the variable-at-a-time Metropolis sampling algorithm to estimate the mean and Bayesian confidence interval for each parameter in turn. As a numerical example, this integrated approach is applied on the metro network in Singapore. Our result shows that link travel time exhibits a considerable coefficient of variation about 0.17, suggesting that travel time reliability is of high importance to metro operation. The estimation of route choice parameters conforms with previous survey-based study, showing that showing that the disutility of transfer time is about twice of that of in-vehicle travel time in Singapore metro system.2
Published in: Transportation research Part C, Emerging technologies
Volume: 52
Pages: 116 - 131
ISSN: 0968-090X
Publication date / Date received: 2015-03-01
Publication status: Pergamon
Publication status: Published
Subjects: Verkehr und Transport|Traffic and Transportation, Bayesian inference, Metro network, Travel time, Smart card, Route choice
Language: English
Keyword: Bayesian inference, Metro network, Travel time, Smart card, Route choice
DBID source: FORM-1413040517, SCOPUS-84922756795, WOS-000352252400008
DOI: 10.1016/j.trc.2015.01.001
Nebis system number: 000889058
, Sun, Lijun, Lu, Yang, Lee, Der-Horng, 2015 >>
Author(s): Sun, Lijun, Lu, Yang, Lee, Der-Horng
Title: Understanding the structure of urban bus networks: the C-space representation approach
Abstract: The application of network science has greatly improved our understanding about the structure and properties of public transport network (PTN). Using tools and methods provided from network science, several standardized representations have been developed and analyzed to understand the topological structure of PTN from different aspects. In this paper, we present an empirical study on the bus network in Singapore. Different from previous studies based on a direct mapping of PTN on road networks, we focus on the weighted C-space representation of public transport networks to better characterize the interaction of different bus services. By exploring the statistical properties of this representation, we find that the bus network in Singapore exhibits similar patterns as many other cities in terms of distributions of edge weight, vertex degree and vertex strength. However, a superlinear scaling is found when we examine the dependency of a vertex's strength on degree, indicating that PTN in Singapore provides people with more alternatives to travel and transfer. The C-space representation also enables us to further explore the interactions between services by examining the community structure and the corresponding reverse mapping on road networks. This helps us to identify those crucial 'bridges' in a city, which is shared by different communities and connect diverse regions.2
Book title: CICTP 2015 : efficient, safe, and green multimodal transportation : proceedings of the 15th COTA International Conference of Transportation Professionals, July 24-27, 2015, Beijing, China
Pages: 1557 - 1567
ISBN: 978-0-7844-7929-2
Publication date / Date received: 2015-01-01
Publication status: Reston, VA
Publication status: Published
Event name: 15th COTA International Conference of Transportation Professionals (CICTP 2015)
Event date: July 25-27, 2015
Place: Bejing, China
Language: English
DBID source: FORM-1441379697
DOI: 10.1061/9780784479292.143
, Sun, Lijun, Jin, Jian Gang, Lee, Der-Horng, Axhausen, Kay W., 2015 >>
Author(s): Sun, Lijun, Jin, Jian Gang, Lee, Der-Horng, Axhausen, Kay W.
Title: Characterizing travel time reliability and passenger path choice in a metro network
Abstract: This paper characterizes travel time reliability in a metro network by estimating link cost and its variability. To quantify metro travel time in-depth, we reconstruct a metro network with three types of nodes (departure/arrival, platform and fare gantry) and four types of links (walking, waiting, on-board and transfer) and apply an iterative method to estimate the mean and standard deviation of link costs using real-world travel time observations from smart card data. The key principle of this estimation if to identify those OD pairs with only one realistic path. In a complex metro network, a crucial problem is to identify the paths that passengers choose when multiple realistic alternatives exist. This is important for understanding travel behavior and characterizing assignment models for metro networks. Using the estimated link costs, we can estimate the proportions of passenger choosing each alternative path by applying maximum likelihood estimation. In general, the proposed methodology could be applied to other metro systems with travel time observations available, serving to better understand spatial-temporal demand patterns and passenger path choice behavior.2
Published in: Arbeitsberichte Verkehrs- und Raumplanung
Volume: 916
Publication date / Date received: 2015-01-01
Publication status: Zürich
Publication status: Published
Subjects: Metro network, Travel time reliability, Path choice, Travel behavior
Event name: 94th Annual Meeting of the Transportation Research Board (TRB 2015)
Event date: January 11-15, 2015
Place: Washington, D.C., USA
Language: English
Keyword: Metro network, Travel time reliability, Path choice, Travel behavior
DBID source: FORM-1376649049
, Sun, Lijun, Jin, Jian Gang, Axhausen, Kay W., Lee, Der-Horng, Cebrian, Manuel, 2015 >>
Author(s): Sun, Lijun, Jin, Jian Gang, Axhausen, Kay W., Lee, Der-Horng, Cebrian, Manuel
Title: Quantifying long-term evolution of intra-urban spatial interactions
Abstract: Understanding the long-term impact that changes in a city's transportation infrastructure have on its spatial interactions remains a challenge. The difficulty arises from the fact that the real impact may not be revealed in static or aggregated mobility measures, as these are remarkably robust to perturbations. More generally, the lack of longitudinal, cross-sectional data demonstrating the evolution of spatial interactions at a meaningful urban scale also hinders us from evaluating the sensitivity of movement indicators, limiting our capacity to understand the evolution of urban mobility in depth. Using very large mobility records distributed over 3 years, we quantify the impact of the completion of a metro line extension: the Circle Line (CCL) in Singapore. We find that the commonly used movement indicators are almost identical before and after the project was completed. However, in comparing the temporal community structure across years, we do observe significant differences in the spatial reorganization of the affected geographical areas. The completion of CCL enables travellers to re-identify their desired destinations collectively with lower transport cost, making the community structure more consistent. These changes in locality are dynamic and characterized over short timescales, offering us a different approach to identify and analyse the long-term impact of new infrastructures on cities and their evolution dynamics.2
Published in: Interface : journal of the Royal Society
Volume: 12
Issue: 102
Pages: 20141089
ISSN: 2042-8898, 2042-8901
Publication date / Date received: 2015-01-01
Publication status: London
Publication status: Published
Subjects: Complex networks, Smart card, Human mobility, Urban evolution, Transportation
Language: English
Keyword: Complex networks, Smart card, Human mobility, Urban evolution, Transportation
DBID source: FORM-1404765128
DOI: 10.1098/rsif.2014.1089
Nebis system number: 006184510
, Sun, Lijun, Jin, Jian Gang, 2015 >>
Author(s): Sun, Lijun, Jin, Jian Gang
Title: Modeling temporal flow assignment in metro networks using smart card data
Abstract: Understanding passenger flow assignment patterns in a complex metro network is crucial to maintaining service reliability and developing efficient response during disruptions. In reality passengers' perception of different cost attributes may vary with time. This paper focuses on quantifying the temporal variation of passenger route choice behavior and its impact on overall passenger flow assignment. In order to efficiently estimate model parameters, we adapt a previous model to a missing data problem by introducing latent variables on route choice outcomes for each travel time observation. The revised model can be estimated using expectation-maximization (EM) algorithm. We apply the proposed framework on Singapore's metro system and temporal grouped smart card transactions. We find that route choice coefficients vary substantially with time. The relative value of transfer time in terms of in-vehicle time ranges from 2 to 3, being higher at off-peak hours than during morning/evening peaks. The result suggests that passenger care more about total travel time during peak hours, whereas comfort (e.g., less transfer time) is of more concern during off-peaks. The proposed framework is general and can be applied on other networks.2
Publication date / Date received: 2015-01-01
Publication status: Piscataway, NJ
Publication status: Accepted
Subjects: Data-driven, Metro network, Smart card data, Route choice, Flow assignment
Event name: 18th International IEEE Conference on Intelligent Transportation Systems (ITSC 2015)
Event date: September 15-18, 2015
Place: Las Palmas de Gran Canaria, Spain
Language: English
Keyword: Data-driven, Metro network, Smart card data, Route choice, Flow assignment
DBID source: FORM-1435846055
, Sun, Lijun, Axhausen, Kay W., Lee, Der-Horng, Cebrian, Manuel, 2015 >>
Author(s): Sun, Lijun, Axhausen, Kay W., Lee, Der-Horng, Cebrian, Manuel
Title: Supplementary Information for "Quantifying long-term evolution of intra-urban spatial interactions"
Abstract: 2
Published in: Interface : journal of the Royal Society
Volume: 12
Issue: 102
Pages: 20141089
ISSN: 2042-8898, 2042-8901
Publication date / Date received: 2015-01-01
Publication status: London
Publication status: Published
Language: English
DBID source: FORM-1448521685
DOI: 10.1098/rsif.2014.1089
Nebis system number: 006184510
, Erath, Alexander L., Fourie, Pieter J., Sun, Lijun, Ordóñez Medina, Sergio A., Chakirov, Artem, 2015 >>
Author(s): Erath, Alexander L., Fourie, Pieter J., Sun, Lijun, Ordóñez Medina, Sergio A., Chakirov, Artem
Title: From Big Data to Smart Data: Developing a MATSim Model That Tuns on Smart Card Data
Abstract: 2
Publication date / Date received: 2015-01-01
Publication status: Zürich
Publication status: Published
Event name: IVT-Seminar
Event date: August 7, 2015
Place: ETH Zürich
Language: English
DBID source: FORM-1439297441
, Sun, Lijun, Tirachini, Alejandro, Axhausen, Kay W., Erath, Alexander, Lee, Der-Horng, 2014 >>
Author(s): Sun, Lijun, Tirachini, Alejandro, Axhausen, Kay W., Erath, Alexander, Lee, Der-Horng
Title: Models of bus boarding and alighting dynamics
Abstract: Understanding the dynamics of boarding/alighting activities and its impact on bus dwell times is crucial to improving bus service levels. However, research is limited as conventional data collection methods are both time and labour intensive. In this paper, we present the first use of smart card data to study passenger boarding/alighting behaviour and its impact on bus dwell time. Given the nature of these data, we focus on passenger activity time and do not account for the time necessary to open and close doors. We study single decker, double decker and articulated buses and identify the specific effects of floor/entrance type, number of activities and occupancy on both boarding and alighting dynamics. A linear relationship between average boarding and alighting times and their respective standard deviations is also found, whereas the variability of boarding and alighting time decreases with the number of passengers boarding and alighting. After observing the cumulative boarding/alighting processes under different occupancy conditions, we propose a new model to estimate passenger activity time, by introducing critical occupancy – a parameter incorporating the friction between boarding/alighting and on-board passengers. We conduct regression analyses with the proposed and another popular model for simultaneous boarding/alighting processes, finding that the critical occupancy plays a significant role in determining the regime of boarding and alighting processes and the overall activity time. Our results provide potential implications for practice and policy, such as identifying optimal vehicle for a particular route and modelling transit service reliability2
Published in: Transportation research. Part A, Policy and practice
Volume: 69
Pages: 447 - 460
ISSN: 0965-8564, 1879-2375
Publication date / Date received: 2014-11-01
Publication status: Amsterdam
Publication status: Published
Subjects: Verkehr und Transport|Traffic and Transportation, Boarding/alighting dynamics, Bus dwell time, Crowding, Smart card data, Bus configuration, Public transit
Language: English
Keyword: Boarding/alighting dynamics, Bus dwell time, Crowding, Smart card data, Bus configuration, Public transit
DBID source: FORM-1374507573, SCOPUS-84908365299
DOI: 10.1016/j.tra.2014.09.007
Nebis system number: 000006552
, Sun, Lijun, Jin, Jian Gang, Lee, Der-Horng, Axhausen, Kay W., Erath, Alexander, 2014 >>
Author(s): Sun, Lijun, Jin, Jian Gang, Lee, Der-Horng, Axhausen, Kay W., Erath, Alexander
Title: Demand-driven timetable design for metro services
Abstract: Timetable design is crucial to the metro service reliability. A straightforward and commonly adopted strategy in daily operation is a peak/off-peak-based schedule. However, such a strategy may fail to meet dynamic temporal passenger demand, resulting in long passenger waiting time at platforms and over-crowding in trains. Thanks to the emergence of smart card-based automated fare collection systems, we can now better quantify spatial-temporal demand on a microscopic level. In this paper, we formulate three optimization models to design demand-sensitive timetables by demonstrating train operation using equivalent time (interval). The first model aims at making the timetable more dynamic; the second model is an extension allowing for capacity constraints. The third model aims at designing a capacitated demand-sensitive peak/off-peak timetable. We assessed the performance of these three models and conducted sensitivity analyses on different parameters on a metro line in Singapore, finding that dynamical timetable built with capacity constraints is most advantageous. Finally, we conclude our study and discuss the implications of the three models: the capacitated model provides a timetable which shows best performance under fixed capacity constraints, while the uncapacitated model may offer optimal temporal train configuration. Although we imposed capacity constraints when designing the optimal peak/off-peak timetable, its performance is not as good as models with dynamical headways. However, it shows advantages such as being easier to operate and more understandable to the passengers.2
Published in: Transportation research. Part C, Emerging technologies
Volume: 46
Pages: 284 - 299
ISSN: 0968-090X
Publication date / Date received: 2014-09-01
Publication status: Oxford
Publication status: Published
Subjects: Metro system, Timetable, Smart card, Demand-driven
Language: English
Keyword: Metro system, Timetable, Smart card, Demand-driven
DBID source: FORM-1376651096, WOS-000343387300019
DOI: 10.1016/j.trc.2014.06.003
Nebis system number: 000889058
, Jin, Jian Gang, Tang, Loon Ching, Sun, Lijun, Lee, Der-Horng, 2014 >>
Author(s): Jin, Jian Gang, Tang, Loon Ching, Sun, Lijun, Lee, Der-Horng
Title: Enhancing metro network resilience via localized integration with bus services
Abstract: This paper advances the field of network disruption analysis by introducing an application to a multi-modal transport network, capitalizing on the redundancies and improved connectivity of an integrated metro-bus network. Metro network resilience to disruptions can be enhanced by leveraging on public bus services. To ensure better acceptance among operators and commuters, we focus on introducing localized integration with bus services instead of designing an entirely new bus network to achieve the desired resilience to potential disruptions. This is accomplished by increasing the capacity of bus services that run in parallel with affected metro lines as well as those connecting to different metro lines. Our analysis starts with a network representation to model the integrated metro and bus system. A two-stage stochastic programming model is further developed to assess the intrinsic metro network resilience as well as to optimize the localized integration with bus services. The approach is applied to a case study based on the Singapore public transit system and actual travel demand data. The results show that the metro network resilience to disruptions can be enhanced significantly from localized integration with public bus services.2
Published in: Transportation research Part E, Logistics and transportation review
Volume: 63
Pages: 17 - 30
ISSN: 1366-5545
Publication date / Date received: 2014-03-01
Publication status: Amsterdam
Publication status: Published
Subjects: Verkehr und Transport|Traffic and Transportation
Language: English
DBID source: FORM-1393583627
DOI: 10.1016/j.tre.2014.01.002
Nebis system number: 004141982
, Sun, Lijun, Jin, Jian Gang, Lee, Der-Horng, Axhausen, Kay W., 2014 >>
Author(s): Sun, Lijun, Jin, Jian Gang, Lee, Der-Horng, Axhausen, Kay W.
Title: Characterizing multimodal transfer time using smart card data
Subtitle: The effect of time, passenger age, crowdedness and collective pressure
Abstract: Understanding passenger transfer behavior is crucial to designing better multimodal transport networks and improving public transport service quality. However, obtaining data for modeling transfer behavior remains a challenge, in particular under complex facility configurations. The recent emergence of smart card data provides us with new and efficient data-driven approaches to modeling public transport systems. In this paper, we present the effect of time of day, day of week, age of passengers, crowdedness at stop/station and collective pressure in determining passenger transfer time. By analyzing transfer profiles provided by smart card transactions, we apply regression models to estimate the impact of each factor in determining passenger behavior under different scenarios. Using morning peak period as a base category, we find that passengers are faster during morning peaks even though it is more crowded. In terms of age of passengers, we find that children and senior citizens generally transfer slower than adults. However, children may outperform adults in passing through an overpass. The crowding effect at bus stop is not substantial unless passenger demand reaches its capacity, while the crowdedness at fare gantries always delays transferring. Finally, we identify the effect of collective pressure by using the number of fastest/slowest passengers around one individual as a proxy. A fast passenger around one individual is found to reduce his/her transfer time, while a slow passenger may delay the transfer significantly. This work presents some empirical evidence in understanding passenger transfer behavior in a multimodal transit network. The results could be integrated with physical surveys to better model pedestrian behaviors, supporting convenient facility design and public policy making.2
Published in: Arbeitsberichte Raum- und Verkehrsplanung
Volume: 1013
Publication date / Date received: 2014-01-01
Publication status: Zürich
Publication status: Published
Language: English
DBID source: FORM-1406994213
, Sun, Lijun, Axhausen, Kay W., Lee, Der-Horng, Cebrian, Manuel, 2014 >>
Author(s): Sun, Lijun, Axhausen, Kay W., Lee, Der-Horng, Cebrian, Manuel
Title: Efficient detection of contagious outbreaks in massive metropolitan encounter networks
Abstract: Physical contact remains difficult to trace in large metropolitan networks, though it is a key vehicle for the transmission of contagious outbreaks. Co-presence encounters during daily transit use provide us with a city-scale time-resolved physical contact network, consisting of 1 billion contacts among 3 million transit users. Here, we study the advantage that knowledge of such co-presence structures may provide for early detection of contagious outbreaks. We first examine the ''friend sensor'' scheme - a simple, but universal strategy requiring only local information - and demonstrate that it provides significant early detection of simulated outbreaks. Taking advantage of the full network structure, we then identify advanced ''global sensor sets'', obtaining substantial early warning times savings over the friends sensor scheme. Individuals with highest number of encounters are the most efficient sensors, with performance comparable to individuals with the highest travel frequency, exploratory behavior and structural centrality. An efficiency balance emerges when testing the dependency on sensor size and evaluating sensor reliability; we find that substantial and reliable lead-time could be attained by monitoring only 0.01% of the population with the highest degree.
Published in: Scientific Reports
Volume: 4
Pages: 5099
ISSN: 2045-2322
Publication date / Date received: 2014-01-01
Publication status: London
Publication status: Published
Language: English
DBID source: FORM-1390380074, SCOPUS-84902153698, WOS-000336835600001
DOI: 10.1038/srep05099
Nebis system number: 006751867
, Sun, Lijun, 2014 >>
Author(s): Sun, Lijun
Title: Quantifying long-term evolution of intra-urban spatial interactions
Publication date / Date received: 2014-01-01
Publication status: Published
Event name: Urban Systems and Networks (NetSci Satellite)
Event date: June 2, 2014
Place: Berkeley, CA, USA
Language: English
DBID source: FORM-1404411384
, Sun, Lijun, 2014 >>
Author(s): Sun, Lijun
Title: Efficient detection of contagious outbreaks in massive metropolitan encounter networks
Publication date / Date received: 2014-01-01
Publication status: Published
Event name: International School and Conference on Network Science (NetSci 2014)
Event date: June 2-6, 2014
Place: Berkeley, CA, USA
Language: English
DBID source: FORM-1404411657
, Sun, Lijun, 2014 >>
Author(s): Sun, Lijun
Title: Characterizing Travel Time Reliability and Passenger Path Choice in a Metro Network
Abstract: 2
Publication date / Date received: 2014-01-01
Publication status: Leeds, UK
Publication status: Published
Event name: 3rd Symposium of the European Association for Research in Transportation (hEART 2014)
Event date: September 10-12, 2014
Place: Leeds, UK
Language: English
DBID source: FORM-1411115966
, Jin, Jian Gang, Tang, Loon Ching, Sun, Lijun, Lee, Der-Horng, 2014 >>
Author(s): Jin, Jian Gang, Tang, Loon Ching, Sun, Lijun, Lee, Der-Horng
Title: Enhancing metro network resilience via localized integration with bus services
Abstract: This paper advances the field of network disruption analysis by introducing an application to a multi-modal transport network, capitalizing on the redundancies and improved connectivity of an integrated metro-bus network. Metro network resilience to disruptions can be enhanced by leveraging on public bus services. To ensure better acceptance among operators and commuters, we focus on introducing localized integration with bus services instead of designing an entirely new bus network to achieve the desired resilience to potential disruptions. This is accomplished by increasing the capacity of bus services that run in parallel with affected metro lines as well as those connecting to different metro lines. Our analysis starts with a network representation to model the integrated metro and bus system. A two-stage stochastic programming model is further developed to assess the intrinsic metro network resilience as well as to optimize the localized integration with bus services. The approach is applied to a case study based on the Singapore public transit system and actual travel demand data. The results show that the metro network resilience to disruptions can be enhanced significantly from localized integration with public bus services.2
Published in: Transportation research. Part E, Logistics and transportation review
Volume: 63
Pages: 17 - 30
ISSN: 1366-5545
Publication date / Date received: 2014-01-01
Publication status: S.l.
Publication status: Published
Subjects: Metro system, Resilience, Network disruption, Bus service, Public transport
Language: English
Keyword: Metro system, Resilience, Network disruption, Bus service, Public transport
DBID source: FORM-1413043429
DOI: http://doi.org/10.1016/j.tre.2014.01.002
Nebis system number: 004141982
, Sun, Lijun, 2013 >>
Author(s): Sun, Lijun
Title: Familiar Strangers
Abstract: Everyone who has taken public transport on a regular basis has experienced the sense of being familiar with somebody even without knowing his or her name or having spoken to them. Lijun Sun and the team from Mobility and Transport Planning research module at the Future Cities Laboratory in Singapore investigate this phenomena of the Familiar Stranger.2
Published in: NSL Newsletter
Volume: 19
Publication date / Date received: 2013-09-01
Publication status: Zürich
Publication status: Published
Language: English
DBID source: FORM-1419686699
, Tirachini, Alejandro, Sun, Lijun, Erath, Alexander, 2013 >>
Author(s): Tirachini, Alejandro, Sun, Lijun, Erath, Alexander
Title: Valuation of sitting and standing in public transport using revealed preferences
Abstract: 2
Published in: Arbeitsberichte Verkehrs- und Raumplanung
Volume: 919
Publication date / Date received: 2013-01-01
Publication status: Zürich
Publication status: Unpublished
Language: English
DBID source: FORM-1376652322
, Sun, Lijun, Axhausen, Kay W., Lee, Der-Horng, Huang, Xianfeng, 2013 >>
Author(s): Sun, Lijun, Axhausen, Kay W., Lee, Der-Horng, Huang, Xianfeng
Title: Understanding metropolitan patterns of daily encounters
Abstract: Understanding of the mechanisms driving our daily face-to-face encounters is still limited; the field lacks large-scale datasets describing both individual behaviors and their collective interactions. However, here, with the help of travel smart card data, we uncover such encounter mechanisms and structures by constructing a time-resolved in-vehicle social encounter network on public buses in a city (about 5 million residents). This is the first time that such a large network of encounters has been identified and analyzed. Using a population scale dataset, we find physical encounters display reproducible temporal patterns, indicating that repeated encounters are regular and identical. On an individual scale, we find that collective regularities dominate distinct encounters' bounded nature. An individual's encounter capability is rooted in his/her daily behavioral regularity, explaining the emergence of "familiar strangers" in daily life. Strikingly, we find individuals with repeated encounters are not grouped into small communities, but become strongly connected over time, resulting in a large, but imperceptible, small-world contact network or "structure of co-presence" across the whole metropolitan area. Revealing the encounter pattern and identifying this large-scale contact network are crucial to understanding the dynamics in patterns of social acquaintances, collective human behaviors, and – particularly – disclosing the impact of human behavior on various diffusion/spreading processes.
Published in: Proceedings of the National Academy of Sciences of the United States of America
Volume: 110
Issue: 34
Pages: 13774 - 13779
ISSN: 0027-8424, 1091-6490
Publication date / Date received: 2013-01-01
Publication status: Washington, DC
Publication status: Published
Subjects: Human mobility, Behavioral rhythms, Social networks, Social sciences
Language: English
Keyword: Human mobility, Behavioral rhythms, Social networks, Social sciences
DBID source: FORM-1373573083, SCOPUS-84882800907
DOI: 10.1073/pnas.1306440110
Nebis system number: 001003347
, Sun, Lijun, Axhausen, Kay W., 2013 >>
Author(s): Sun, Lijun, Axhausen, Kay W.
Title: Familiar strangers
Subtitle: Understanding metropolitan patterns of daily encounters
Abstract: 2
Publication date / Date received: 2013-01-01
Publication status: Published
Event name: International School and Conference on Network Science 2013
Event date: June 3-7, 2013
Place: Copenhagen, Denmark
Language: English
DBID source: FORM-1376653684
, Lee, Der-Horng, Wu, Xian, Sun, Lijun, 2013 >>
Author(s): Lee, Der-Horng, Wu, Xian, Sun, Lijun
Title: Limited Information Sharing Strategy for the Taxi-Customer Searching Problem in Non-Booking Taxi Service
Abstract: One of the issues existed in the current taxi service is the imbalance between supply and demand. In response to this issue, the automatic taxi dispatching approach in which customers can book taxis through phones or mobile devices is widely used in many large cities worldwide. However, the utilization of this approach is not satisfied, since most customers still prefer the Non-Booking Taxi Service (NBTS) that taking the taxi by either waiting at taxi stand or hailing on the street. One important reason for this phenomenon is that the customer takes lower risk in NBTS: they are free from complicated booking procedures and have no commitment to any yet-arrived taxis. In order to facilitate the taxi-customer matching process in NBTS, this paper has proposed a novel control strategy namely the Limited Information Sharing Strategy (LISS) for the Taxi-Customer Searching Problem (TCSP) in NBTS, in which both the taxi and the customer are equipped with mobile devices that can communicate with each other within limited searching ranges. The proposed LISS is based on the game-theoretical formulation in which a learning algorithm is developed to find the pure Nash-Equilibrium (NE). A microscopic traffic simulation model is developed for the evaluation of the LISS. The simulation results show that the proposed LISS is an effective control strategy when taxi supply is low, and it will not increase the risk of taxi in terms of losing the total occupied time.2
Book title: Network modeling 2013
Published in: Transportation research record
Volume: 2333
Pages: 46 - 54
ISBN: 978-0-309-26338-2
Publication date / Date received: 2013-01-01
Publication status: Washington, DC
Publication status: Published
Subjects: Game theory, Limited Information Sharing Strategy (LISS), Microscopic traffic simulation, Non-Booking Taxi Service (NBTS), Taxi-Customer Searching Problem (TCSP)
Event name: 92nd Annual Meeting of the Transportation Research Board
Event date: January 13-17, 2013
Place: Washington, DC, USA
Language: English
Keyword: Game theory, Limited Information Sharing Strategy (LISS), Microscopic traffic simulation, Non-Booking Taxi Service (NBTS), Taxi-Customer Searching Problem (TCSP)
DBID source: FORM-1369654917
DOI: 10.3141/2333-06
Nebis system number: 009974953
, Jin, Jian Gang, Teo, Kwong Meng, Sun, Lijun, 2013 >>
Author(s): Jin, Jian Gang, Teo, Kwong Meng, Sun, Lijun
Title: Disruption Response Planning for an Urban Mass Rapid Transit Network
Abstract: Given many cities' growing dependence on public rail transport, simple network disruptions can lead to widespread confusion and significant productivity loss to the society. Therefore, a sys- tematic approach to develop efficient disruption response and minimize the negative impacts is required. In this paper, we develop a planning procedure to supplement a degraded urban mass rapid transit network through intelligent introduction of shuttle bus services in the disrupted area. The proposed method includes two important mechanisms, namely (1) using column generation to identify all beneficial bus routes, including those which might not be intuitively found, and (2) using a path-based multi-commodity flow formulation to select the best among these candidate bus routes. Finally, the method is applied to two disruption case studies defined using real-world data; the corresponding results confirmed the practicality of the proposed approach: (1) the procedure can be carried out efficiently, (2) introducing bus routes to the naive bridging services can eas- ily yield significant improvement on commuters' travel delay, (3) the distribution of commuters' travel delay is improved considerably with an optimized response, and (4) many realistic operating constraints can be handled in planning process.
Publication date / Date received: 2013-01-01
Publication status: Published
Event name: 92nd Annual Meeting of the Transportation Research Board
Event date: January 13-17, 2013
Place: Washington, DC, USA
Language: English
DBID source: FORM-1369670970
, Jin, Jian Gang, Tang, Loon Ching, Sun, Lijun, Lee, Der-Horng, 2013 >>
Author(s): Jin, Jian Gang, Tang, Loon Ching, Sun, Lijun, Lee, Der-Horng
Title: Improving metro network resilience by incremental bus service adjustment
Abstract: This paper aims to enhance the resilience of metro networks by leveraging on public bus services. To ensure better acceptance among operators and commuters, we focus on introducing localized integration with bus services instead of designing an entirely new bus network to achieve the desired resilience to potential disruptions. This is accomplished by increasing the capacity of bus services that run in parallel with affected metro lines as well as those connecting to different metro lines. Our analysis starts with a network representation to model the integrated metro and bus system. A two-stage stochastic programming model is further developed to assess the current metro network resilience as well as to optimize the local integration with bus services. A case study based on the Singapore public transit system helps to validate the effectiveness of the proposed localized integration between the metro and public bus systems.2
Published in: Arbeitsberichte Verkehrs- und Raumplanung
Volume: 918
Publication date / Date received: 2013-01-01
Publication status: Zürich
Publication status: Accepted
Language: English
DBID source: FORM-1376651917
, Erath, Alexander L., Chakirov, Artem, Eggermond, Michael A.B. van, Fourie, Pieter J., Ordóñez Medina, Sergio A., Sun, Lijun, Axhausen, Kay W., 2013 >>
Author(s): Erath, Alexander L., Chakirov, Artem, Eggermond, Michael A.B. van, Fourie, Pieter J., Ordóñez Medina, Sergio A., Sun, Lijun, Axhausen, Kay W.
Title: Presentation for LTA steering committee
Abstract: 2
Publication date / Date received: 2013-01-01
Event name: LTA – FCL Steering committee – Meeting 5
Event date: May 2013
Place: Singapore
Language: English
DBID source: FORM-1446796911
, Sun, Lijun, Gang Jin, Jian, Lee, Der-Horng, Erath, Alexander, 2012 >>
Author(s): Sun, Lijun, Gang Jin, Jian, Lee, Der-Horng, Erath, Alexander
Title: Designing a demand responsive timetable for MRT services
Abstract: Mass rapid transit systems (MRT) have become the most important public transport mode in many major cities globally, given its advantages in larger capacity, faster velocity and higher reliability compared with other modes. Hence, various projects directed to improve service quality of MRT systems by optimizing operation strategies have been conducted worldwide. Among numerous methods to adjust operation parameters for MRT services, timetable optimization has emerged as the simplest and most effective cure. On one hand, a demand responsive timetable has the potential to improve service quality by reducing both waiting time and crowdedness on trains. On the other hand, for transit operators, a demand responsive timetable will improve operation stability and hence reliability. In this study, we propose an optimization model to solve timetable scheduling considering fine grained dynamic demand data. The objective is to minimize the total waiting time for all the passengers. Historical demand data extracted from smart card system is used as inputs. Then, a predefined demand responsive timetable will be generated with the optimization model. Since operational constraints such as the number of available trains and minimal headway are considered as boundary conditions, we ensure that the proposed schedule actually has the potential to be implemented in actual operation. A case study on a representative MRT service is conducted and presented in this paper. In the absence of effective/operated timetable, simulations on the optimal timetable obtained from this proposed model and simplified timetable as extracted from Google Maps are performed based on detailed travel demand extracted from smart card transactions. The result demonstrates the applicability of the proposed model in designing a demand sensitive timetable and its potential to minimize waiting times. However, simplified assumptions concerning potential operational constraints when switching directions or manpower scheduling, restrain the immediate application of the obtained results.2
Published in: Arbeitsberichte Verkehrs- und Raumplanung
Volume: 795
Publication date / Date received: 2012-07-01
Publication status: Zürich
Publication status: Published
Subjects: Timetable, MRT, Public transit
Language: English
Keyword: Timetable, MRT, Public transit
DBID source: FORM-1343999963
DOI: 10.3929/ethz-a-007340032
Nebis system number: 007340032
, Sun, Lijun, Lee, Der-Horng, Erath, Alexander, Huang, Xianfeng, 2012 >>
Author(s): Sun, Lijun, Lee, Der-Horng, Erath, Alexander, Huang, Xianfeng
Title: Using Smart Card Data to Extract Passenger's Spatio-temporal Density and Train's Trajectory of MRT System
Abstract: Rapid tranit systems are the most important public transportation service modes in many large cities around the world. Hence, its service reliability is of high importance for government and transit agencies. Despite taking all the necessary precautions, disruptions cannot be entirely prevented but what transit agencies can do is to prepare to respond to failure in a timely and effective manner. To this end, information about daily travel demand patterns are crucial to develop efficient failure response strategies. To the extent of urban computing, smart card data offers us the opportunity to investigate and understand the demand pattern of passengers and service level from transit operators. In this present study, we present a methodology to analyze smart card data collected in Singapore, to describe dynamic demand characteristics of one case mass rapid transit (MRT) service. The smart card reader registers passengers when they enter and leave an MRT station. Between tapping in and out of MRT stations, passengers are either walking to and fro the platform as they alight and board on the trains or they are traveling in the train. To reveal the effective position of the passengers, a regression model based on the observations from the fastest passengers for each origin destination pair has been developed. By applying this model to all other observations, the model allows us to divide passengers in the MRT system into two groups, passengers on the trains and passengers waiting in the stations. The estimation model provides the spatio-temporal density of passengers. From the density plots, trains' trajectories can be identified and passengers can be assigned to single trains according to the estimated location. Thus, with this model, the location of a certain train and the number of onboard passengers can be estimated, which can further enable transit agencies to improve their response to service disruptions. Since the respective final destination can also be derived from the data set, one can develop effective failure response scenarios such as the planning of contingency buses that bring passengers directly to their final destinations and thus relieves the bridging buses that are typically made available in such situations.
Book title: Proceedings of the ACM SIGKDD International Workshop on Urban Computing
Pages: 142 - 148
ISBN: 978-1-4503-1542-5
Publication date / Date received: 2012-01-01
Publication status: New York, NY
Publication status: Published
Event name: ACM SIGKDD International Workshop on Urban Computing (UrbComp 2012)
Event date: August 12-16, 2012
Place: Beijing, China
Language: English
DBID source: FORM-1347369320
DOI: 10.1145/2346496.2346519
, Sun, Lijun, Gang Jin, J., Lee, D.-H., Erath, Alexander, 2012 >>
Author(s): Sun, Lijun, Gang Jin, J., Lee, D.-H., Erath, Alexander
Title: Designing a demand responsive timetable for MRT services
Publication date / Date received: 2012-01-01
Publication status: Published
Event name: 2nd Future Cities Laboratory Conference : Territorial Encounters
Event date: September 10-11, 2012
Place: Zürich, Switzerland
Language: English
Review status: Unknown
DBID source: FORM-1347377412
, Lee, Der-Horng, Sun, Lijun, Erath, Alex, 2012 >>
Author(s): Lee, Der-Horng, Sun, Lijun, Erath, Alex
Title: Study of bus service reliability in Singapore using fare card data
Publication date / Date received: 2012-01-01
Publication status: Published
Event name: 12th Asia-Pacific ITS Forum & Exhibition 2012
Event date: April 16-18, 2012
Place: Kuala Lumpur, Malaysia
Language: English
DBID source: FORM-1347367052
, Lee, Der-Horng, Sun, Lijun, Erath, Alex, 2012 >>
Author(s): Lee, Der-Horng, Sun, Lijun, Erath, Alex
Title: Determining Optimal Control Stop to Improve Bus Service Reliability
Publication date / Date received: 2012-01-01
Publication status: Published
Event name: 1st European Symposium on Quantitative Methods in Transportation Systems
Event date: September 4-7, 2012
Place: Lausanne, Switzerland
Language: English
Review status: Unknown
DBID source: FORM-1347369686

 

 

 

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