Sergio Arturo Ordonez Medina


Last Name

Ordonez Medina

First Name

Sergio Arturo

ORCID

0000-0003-3652-2436

Organisational unit

Filters

2012 - 2019112020 - 20245
Reset filters

Search Results

Publications 1 - 10 of 16
  • Simulating urban transport for a week time horizon
    Item type: Working Paper
    Ordonez Medina, Sergio Arturo; Erath, Alexander; Axhausen, Kay W. (2012)
    Arbeitsberichte Verkehrs- und Raumplanung
    MATSim is a large-scale multi-agent, activity-based transport simulation model. It can simulate each person in a urban area, managing millions of agents in reasonable computation times. Besides supply information, MATSim needs a planned activity schedule for every person as input data. Its time horizon is one day, and the activity-trip chains have to be fully defined before each simulation (start-time, duration, location, trip mode, and sequence for the entire day). MATSim scores the simulation, mutates agents' plans and executes a new simulation many times, optimizing the macroscopic indicators and reaching user equilibrium conditions. However, the one day time horizon is a hard restriction for studying current transport planning challenges using MATSim. Recent studies show that the behavioral variety of travelers can not be well analyzed with only one day simulation results. Usual analysis procedures, like clustering the population according to their travel behavior, need multi-day information to account for intra-personal variability. Furthermore, longer time horizons allow to include restrictions like time and money budgets, and to simulate individual mode choice over time, identifying mode clienteles. Developments of advanced time consumption travel models require observations of at least a week for calibration purposes, because a complete cycle of work and leisure must be included. In conclusion, time consumption decisions that humans take inside a day depend on individual and collective behaviors. These behaviors only can be simulated and analyzed with longer term models. Understanding the importance and pertinence of simulating transport with a multi-day time horizon, this paper discusses how MATSim can be expanded to execute one week time activity plans. The discussion is conceptual because no full implementation has been developed yet. The paper emphasizes two key aspects of the expansion: optimization strategies, and the generation of weekly plans. For each aspect alternatives are proposed, analyzed and compared. The impact of the proposed development on each step of the simulation process is taken into account. The problem of scheduling and re-scheduling and its relation to computational time in large-scale scenarios has to be kept in mind for weekly plans even more so than for daily plans. Activity plan generation procedures ranging from simpler, but faster methods to advanced ones, involving econometric approaches or complex mental processes, are compared. Concepts like fixed and floating activities, activity agendas or shared activities (within households or with social networks) have to be evaluated for their impact. Furthermore, several options for performing the optimization of plans are presented, highlighting their advantages and disadvantages (e.g. full-week re-planning or end-of-day re-planning). Computing time and memory consumption are taken into account according to previous measures and expected indicators. It is easy to realize that the mobility simulation (traffic flow) module does not need significant changes when the total time is modified. However, if a within-week re-planning strategy is implemented modifications in this module and its implications are explained and evaluated as well. The paper concludes with a proposed methodology for developing this MATSim extension
  • Engaging active mobility
    Item type: Presentation
    Erath, Alexander; Axhausen, Kay W.; Hölscher, Christoph; et al. (2016)
  • Applications of large-scale, agent-based transport demand simulation for public transport analysis using MATSim
    Item type: Other Conference Item
    Erath, Alexander; Ordonez Medina, Sergio Arturo; Chakirov, Artem; et al. (2013)
  • Synthesising digital twin travellers
    Item type: Working Paper
    Anda, Cuauhtémoc; Ordonez Medina, Sergio Arturo; Axhausen, Kay W. (2020)
    Arbeitsberichte Verkehrs- und Raumplanung
    Mobile phone data generated in mobile communication networks has the potential to improve current travel demand models and in general, how we plan for better urban transportation systems. However, due to its high-dimensionality, even if anonymised there still exists the possibility to reidentify the users behind the mobile phone traces. This risk makes its usage outside the telecommunication network incompatible with recent data privacy regulations, hampering its adoption in transportation-related applications. To address this issue, we propose a framework designed only with user-aggregated mobile phone data to synthesise realistic daily individual mobility — Digital Twin Travellers. We explore different strategies built around modified Markov models and an adaption of the Rejection Sampling algorithm to recreate realistic daily schedules and locations. We also define a one-day mobility population score to measure the similarity between the population of generated agents and the real mobile phone user population. Ultimately, we show how with a series of histograms provided by the telecommunication service provider (TSP) it is possible and plausible to disaggregate them into new synthetic and useful individual-level information, building in this way a big data travel demand framework that is designed in accordance with current data privacy regulations.
  • Lattice Boltzmann Method: A New Alternative for Loss Estimation
    Item type: Journal Article
    Díaz Cruz, Juan C.; Rodríguez, Sergio E.; Ordonez Medina, Sergio Arturo; et al. (2013)
    Chemical Engineering Transactions
  • Privacy-by-design generative models of urban mobility
    Item type: Working Paper
    Anda, Cuauhtémoc; Ordonez Medina, Sergio Arturo (2019)
    Arbeitsberichte Verkehrs- und Raumplanung
    New streams of Location-based Services (LBS) Big data have risen society’s concerns in regards to data privacy. Even though these type of data sets are anonymised and aggregated in space and time, the risk of a privacy breach by user’s re-identification is still imminent. Still, LBS data has the potential to improve current travel demand models and transportation applications. We this in mind, we introduce a Privacy by Design framework that generates realistic disaggregated daily mobility patterns without the need for any personal information or access to individual-level LBS data. On the first step of the framework, we estimate the joint probability distribution of daily mobility patterns using modified Markov models, followed by an adaptation of the rejection sampling algorithm to improve the distribution of the daily tour types. We validate the synthetic mobility patterns against six different distributions and reach an average accuracy over 95%. With this, we hope to open the discussion in the transportation community in regards to data privacy and travel demand models.
  • Estimating dynamic workplace capacities using public transport smart card data and a household travel survey
    Item type: Other Conference Item
    Ordonez Medina, Sergio Arturo; Erath, Alexander (2013)
    This introductory chapter sketches a conceptual framework for the papers presented at the 10th International Conference on Travel Behaviour research, which was organised by the IVT in Lucerne during August 2003.
  • Synthesising digital twin travellers
    Item type: Journal Article
    Anda, Cuauhtémoc; Ordonez Medina, Sergio Arturo; Axhausen, Kay W. (2021)
    Transportation Research Part C: Emerging Technologies
    Mobile phone data generated in mobile communication networks has the potential to improve current travel demand models and in general, how we plan for better urban transportation systems. However, due to its high-dimensionality, even if anonymised there still exists the possibility to re-identify the users behind the mobile phone traces. This risk makes its usage outside the telecommunication network incompatible with recent data privacy regulations, hampering its adoption in transportation-related applications. To address this issue, we propose a framework designed only with user-aggregated mobile phone data to synthesise realistic daily individual mobility — Digital Twin Travellers. We explore different strategies built around modified Markov models and an adaption of the Rejection Sampling algorithm to recreate realistic daily schedules and locations. We also define a one-day mobility population score to measure the similarity between the population of generated agents and the real mobile phone user population. Ultimately, we show how with a series of histograms provided by the telecommunication service provider (TSP) it is possible and plausible to disaggregate them into new synthetic and useful individual-level information, building in this way a big data travel demand framework that is designed in accordance with current data privacy regulations.
  • Introducing the Pedestrian Accessibility Tool (PAT)
    Item type: Conference Paper
    Erath, Alexander; van Eggermond, Michael A.B.; Ordonez Medina, Sergio Arturo; et al. (2017)
    TRB 96th Annual Meeting Compendium of Papers
    The indices for walkability proposed so far are mostly ad-hoc and refer generally to the closest amenities/public transport stops and the existing network structure. They are ad-hoc as the weights of the attributes are generally arbitrary and do not reflect the independently measured preferences of the users and residents. Furthermore, they do not include design attributes such as the location of crossings and walkway design features, which are very relevant for actual planning decisions. In this paper, we propose a walkability index that can be behaviorally calibrated and has been implemented as a GIS tool and is published as Open Source software. The Pedestrian Accessibility Tool allows evaluating existing and future urban plans with regards to walkability. It calculates Hansen-based accessibility indicators based on customizable specification of generalized walking cost and user-defined weights of destination attractiveness. The basic user work flow of the tool is summarized and three case studies show real-world applications of the tool to support the planning of pedestrian infrastructure in an urban context. By indicating potential areas of improvement that have been reported by pilot users working in an urban planning department, we conclude also giving hints for future research.
  • Estimating Dynamic Workplace Capacities by Means of Public Transport Smart Card Data and Household Travel Survey in Singapore
    Item type: Journal Article
    Ordonez Medina, Sergio Arturo; Erath, Alexander (2013)
    Transportation Research Record
    The number and the temporal and spatial distribution of work locations are crucial information for any transport demand model. To generate the initial transport demand of MATSim, an activity-based multiagent simulation framework, it is necessary to determine dynamic workplace capacities with high spatial resolution, either on a parcel or even a building level. Commonly applied methods to derive work locations are based on census of enterprises information, unemployment insurance database, or combined information of a building's gross floor area and individual work space requirements. As an alternative, the authors present a methodology that combines public transport smart card transaction data, travel diary surveys, and building information data sources. Work activities are detected from smart card transactions based on observed activity duration and start time and therefore related to public transport stops. To link the observed work activities to individual buildings, a linear programming optimization technique is applied that minimizes the walking time between public transport stops and potential work locations. The method classifies work activities in representative work schedules obtained by clustering methods. Information on maximum allowed building gross floor area derived from land use regulation is combined with estimates on individual work space requirements to ensure that buildings are only assigned with work activities according to their maximal capacity. To account for private transport based work activities, mode shares as observed in a travel diary are taken into account. To demonstrate the applicability, the proposed approach is implemented in Singapore and the results critically reviewed.
Publications 1 - 10 of 16