Browsing by Author "Kockelman, Kara M."

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    A system of shared autonomous vehicles for Chicago: Understanding the effects of geofencing the service
    (Journal of Transport and Land Use, 2021) Murthy Gurumurthy, Krishna; Auld, Joshua; Kockelman, Kara M.
    With autonomous vehicles (AVs) still in the testing phase, researchers and planners must resort to simulation techniques to explore possible futures regarding shared and automated mobility. An agent-based discrete-event transport simulator, POLARIS, is used in this study to simulate travel in the 20-county Chicago region with a shared AV (SAV) mobility option. Using this framework, the effect of an SAV fleet on system performance when constrained to serve within geofences is studied under four distinct scenarios: service restricted to the city, to the city plus suburban core, to the core plus exurban areas, and to the entire region — along with the choice of dynamic ridesharing (DRS) versus solo travel in an SAV. Results indicate that service areas need a balanced mix of trip generators and attractors, and an SAV fleet’s empty VMT (eVMT) can be noticeably reduced through suitable geofencing and DRS. Geofences can also help lower response times, reduce systemwide VMT across all modes, and ensure uniform access to SAVs. DRS is most useful in lowering VMT and %eVMT that arises from sprawled land development, but with insufficient demand to share rides, savings from the use of geofences is higher. Geofences targeting neighborhoods with high trip density bring about low response times and %eVMT, but fleet sizes in these regions need to be designed for uniformly low response times throughout a large region, as opposed to maximizing vehicle use in a 24-hour day.
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    Urban form and life-cycle energy consumption: Case studies at the city scale
    (Journal of Transport and Land Use, 2015) Nichols, Brice G.; Kockelman, Kara M.
    By combining daily (operations) and embodied energy demands, this work estimates life-cycle energy demands for residents and workers in different city settings. Using life-cycle analyses (LCAs) of different neighborhood types in Austin, Texas, this analysis fabricates five different city types, reflecting actual accessibility and resident and employment density profiles. Five residential and three commercial neighborhood types are distributed across 16-kilometer (10-mile) radius regions, with demographics held constant, for comparability. As expected, per-capita daily energy demands decrease with increased resident and employment density. Interestingly, embodied energy savings via increases in density are substantial. Though embodied energy makes up only 10-20 percent of total life-cycle energy, per-capita savings via density suggest it should be included in planning analyses. Overall, average life-cycle per-capita energy use ranges from 140 gigajoule (GJ)/year/capita in the least dense Orlando-style setting to around 90 GJ/ year/capita in the maximum-density scenario, corresponding to a 35 percent reduction in per-capita energy demand. Energy reductions for Phoenix, Austin, and Seattle settings (relative to an Orlando-based de- sign) are 18, 22, and 24 percent per-capita, respectively. Results provide a rare view of how total annual energy demands in both residential and commercial sectors are affected by density.