od estimation using mobile phone call records

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In this research, we propose a methodology to develop OD matrices using mobile phoneCall Detail Records (CDR) and limited traffic counts. CDR, which consist of time stampedtower locations with caller IDs, are analyzed first and trips occurring within certain timewindows are used to generate tower-to-tower transient OD matrices for different time periods.These are then associated with corresponding nodes of the traffic network and convertedto node-to-node transient OD matrices. The actual OD matrices are derived byscaling up these node-to-node transient OD matrices. An optimization based approach, inconjunction with a microscopic traffic simulation platform, is used to determine the scalingfactors that result best matches with the observed traffic counts. The methodology is demonstratedusing CDR from 2.87 million users of Dhaka, Bangladesh over a month and trafficcounts from 13 key locations over 3 days of that month. The applicability of the methodologyis supported by a validation study.

TRANSCRIPT

  • Development of Origin-Destination

    Matrices Using Mobile Phone Call Data

    Md Shahadat Iqbal, BUET

    Charisma F Choudhury, UoL

    Pu Wang, MIT

    Marta Gonzalez, MIT

    Bangladesh University

    of Engineering and

    Technology

    Massachusetts

    Institute of

    Technology

    University of

    Leeds

  • Data sources Motivation

    Traditional approaches of developing OD matrices rely on roadside and

    household surveys, and/or traffic

    counts

    Limited sample sizes

    Prone to sampling biases, non-response bias and reporting errors

    Lower update frequencies

    High data collection costs

  • Mobile phone CDR Mobile Phone CDR

  • Mobile phone CDR Mobile Phone CDR

  • Coarse granularity

    May not be the final origin/destination

    Only transient ODs (t-Ods)

    False displacements

    Penetration and user bias

    Location bias

    Data 2: Call Detail Records

    Mobile phone CDR Challenges

    B (t-O)

    C

    A (O)

    D

    F (D)

    E (t-D)

  • Proposed framework

    Actual OD = t-OD * penetration factor * phone usage

    factor * vehicle usage factor

    Scaling factor adjusted to match ground truth (traffic counts)

    - Microsimulation tool

    Framework

  • Proposed framework

    Convert tower-to-tower

    transient OD to node-to-

    node transient OD

    Determine scaling factor

    using simulator

    CDR data

    Traffic count data

    Network data

    Generate tower-to-tower

    transient OD matrix

    Actual OD matrix

    Mobile phone CDR Proposed Framework

  • Study area

    Central part of the Dhaka city

    - Area: 300km2 , Pop.:10.7million

    - No automated data collection

    system in place

    Mobile phone penetration rate more than 90%

    Calls from 6.9 million users (65% of the population of the

    study area) over a month

    - 971.33 million anonymized call records

    Mobile phone CDR Case Study

  • Step 1: Generate tower-to-tower t-OD Step 1: Generate Tower-to-tower t-OD

  • Step 2: Convert to node-to-node t-OD

    Step 2: Convert to Node-to-Node t-OD

  • Step 2: Convert to node-to-node t-OD

    Step 2: Convert to Node-to-Node t-OD

  • Step 3: Determine scaling factor

    t-OD from step 2 Seed OD in MITSIMLab

    Scaled up using an optimization based approach

    Step 3: Determine Scaling Factor

  • Step 3: Determine scaling factor Step 3: Determine Scaling Factor

  • Step 3: Determine scaling factor Step 3: Determine Scaling Factor

  • Results 7:00-9:00

    t-OD actual OD

    Results

    7:00-9:00

  • Validation

    Scaled up ODs have been applied to simulate the traffic between 9:00-12:00 in MITSIMLab

    Simulated traffic counts are compared against the observed counts from these locations on a different day

    - Root Mean Square Error 335.09

    - Root Mean Square Percent Errors 13.59%

    Validation

  • Summary

    Mobile phone CDR and limited traffic count data can be successfully combined to generate OD matrices

    More economic than the traditional approaches (CDR already recorded for billing purposes)

    Convenient for periodic update of the OD matrix

    Extendable for dynamic OD estimation

    Particularly effective for generating complex OD matrix where land use pattern is heterogeneous and asymmetry in

    travelling pattern prevails throughout the day but there is a

    limitation of traditional data sources

    Summary

  • Session 842

    Forthcoming issue of Transportation Research Part C

    Email: [email protected]

    Questions?