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PhD defence by Robert Waury

In partial fulfillment of the terms for obtaining the PhD degree, Robert Waury will give a lecture on the following subject: In-Memory Trajectory Indexing for On-The-Fly Travel-Time Estimation on Monday 28th of October 2019, 13:00, in room 0.2.13 at Selma Lagerlöfs Vej 300

Last modified: 10.10.2019


This thesis presents a new method that is able to efficiently select subsets of sub-trajectories from a set of network-constrained vehicle trajectories. The method can be used to improve the quality of histogram-based travel-time estimates for paths in the underlying road network by identifying the trajectories that are most relevant for a given road network path and time.

The thesis shows this with a series of detailed qualitative studies based on real-life trajectory data sets capturing several years of vehicular travel in Northern Denmark. We observe that the quality of travel-time estimates depends heavily on the type of road and whether the road is located in a rural or an urban area.

After demonstrating the quality improvements provided by our method over previous approaches, we design a network-constrained trajectory index to efficiently apply our proposed collection method to compute travel-time histograms. The proposed in-memory index utilizes methods from string processing as a spatial index to identify trajectories in the indexed data that traverse a given path.

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All interested parties are welcome. After the defense the department will be hosting a small reception in cluster 3.