Research ArticleECONOMICS

Do transportation network companies decrease or increase congestion?

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Science Advances  08 May 2019:
Vol. 5, no. 5, eaau2670
DOI: 10.1126/sciadv.aau2670
  • Fig. 1 The p.m. peak period roadway level-of-service (LOS) in San Francisco (30).

    (A) 2009 conditions; (B) 2017 conditions. LOS grades roadways by vehicle delay, from LOS A representing free flow to LOS F representing bumper-to-bumper conditions. Data and an interactive mapping tool are available at congestion.sfcta.org.

  • Fig. 2 Daily TNC pickups and drop-offs for an average Wednesday in fall 2016 (1).

    Darker colors represent a higher density of TNC activity. Data and an interactive mapping tool are available at tncstoday.sfcta.org.

  • Fig. 3 Speed (mph) difference between 2016 scenario with TNCs and a counterfactual 2016 scenario without TNCs.

    Data represent four times of day: (A) 6 to 9 a.m.; (B) 9 a.m. to 3:30 p.m.; (C) 3:30 to 6:30 p.m.; and (D) 6:30 p.m. to 3:00 a.m. Data are provided in the Supplementary Materials.

  • Table 1 Estimated relationships between PTI80 and TTI.

    Facility typeγ1γ2R2
    Freeways and expressways1.0291.4980.831
    Arterials1.1011.3610.862
    Collectors and locals1.1311.4400.762
  • Table 2 Fixed-effects panel estimation results with TNC variables.

    Parameter estimates
    VariableParameterStandard errorT-statistic
    SF-CHAMP background volume0.91720.054116.952
    Presidio Parkway scaling factor−0.36480.0189−19.327
    TNC volume0.68640.07209.5387
    Average impact duration of TNC PUDO on major arterials (s)144.757.719518.751
    Average impact duration of TNC PUDO on minor arterials (s)79.48612.1146.5617
    Model statistics
    Number of entities7081
    Number of time periods2
    R2 between groups0.5819
    R2 within groups0.2985
  • Table 3 Network performance metrics.

    ScenarioNetwork performance metrics
    VMTBased on modeled travel timeBased on observed travel time
    VHTVHDAverage speed (mph)PTI80VHTVHDAverage speed (mph)PTI80
    20104,923,449205,39164,86324.01.83204,68664,15824.11.83
    2016 no TNC5,280,836230,64279,44922.91.94N/AN/AN/AN/A
    2016 with TNC5,559,412266,393105,37720.92.12269,151108,13420.72.21
    ScenarioPercent change from 2010
    VMTBased on modeled travel timeBased on observed travel time
    VHTVHDAverage speed (mph)PTI80VHTVHDAverage speed (mph)PTI80
    20100%0%0%0%0%0%0%0%0%
    2016 no TNC7%12%22%−4%6%N/AN/AN/AN/A
    2016 with TNC13%30%62%−13%15%31%69%−14%21%

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/5/5/eaau2670/DC1

    Supplementary Text

    Fig. S1. Area type map on SF-CHAMP links.

    Table S1. Fixed-effects panel model estimation results only accounting for background traffic.

    Table S2. Network performance metrics by TOD.

    Table S3. Network performance metrics by area type.

    Table S4. Network performance metrics by facility type.

    Data S1. Supporting data for Fig. 1.

    Data S2. Supporting data for Fig. 2.

    Data S3. Model estimation files.

    Data S4. Model application results and supporting data for Fig. 3.

  • Supplementary Materials

    The PDF file includes:

    • Supplementary Text
    • Fig. S1. Area type map on SF-CHAMP links.
    • Table S1. Fixed-effects panel model estimation results only accounting for background traffic.
    • Table S2. Network performance metrics by TOD.
    • Table S3. Network performance metrics by area type.
    • Table S4. Network performance metrics by facility type.
    • Legends for Data S1 to S4

    Download PDF

    Other Supplementary Material for this manuscript includes the following:

    • Data S1 (.zip format). Supporting data for Fig. 1.
    • Data S2 (.zip format). Supporting data for Fig. 2.
    • Data S3 (.zip format). Model estimation files.
    • Data S4 (.zip format). Model application results and supporting data for Fig. 3.

    Files in this Data Supplement:

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