{"title":"Optimal Routing in Stochastic Networks with Reliability Guarantees.","authors":"Wanzheng Zheng, Pranay Thangeda, Yagiz Savas, Melkior Ornik","doi":"10.1109/itsc48978.2021.9564444","DOIUrl":"10.1109/itsc48978.2021.9564444","url":null,"abstract":"<p><p>Optimal routing in highly congested street networks where the travel times are often stochastic is a challenging problem with significant practical interest. While most approaches to this problem use minimizing the expected travel time as the sole objective, such a solution is not always desired, especially when the variance of travel time is high. In this work, we pose the problem of finding a routing policy that minimizes the expected travel time under the hard constraint of retaining a specified probability of on-time arrival. Our approach to this problem models the stochastic travel time on each segment in the road network as a discrete random variable, thus translating the model of interest into a Markov decision process. Such a setting enables us to interpret the problem as a linear program. Our work also includes a case study on the street of Manhattan, New York where we constructed the model of travel times using real-world data, and employed our approach to generate optimal routing policies.</p>","PeriodicalId":93224,"journal":{"name":"Proceedings. IEEE Conference on Intelligent Transportation Systems","volume":"2021 ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8739253/pdf/nihms-1765292.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39801549","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"PROTRIP: Probabilistic Risk-Aware Optimal Transit Planner.","authors":"Pranay Thangeda, Melkior Ornik","doi":"10.1109/itsc45102.2020.9294500","DOIUrl":"10.1109/itsc45102.2020.9294500","url":null,"abstract":"<p><p>Optimal routing in urban transit networks, where variable congestion levels often lead to stochastic travel times, is usually studied with the least expected travel time (LET) as the performance criteria under the assumption of travel time independence on different road segments. However, a LET path might be subjected to high variability of travel time and therefore might not be desirable to transit users seeking a predictable arrival time. Further, there exists a spatial correlation in urban travel times due to the cascading effect of congestion across the road network. In this work, we propose a methodology and a tool that, given an origin-destination pair, a travel time budget, and a measure of the passenger's tolerance for uncertainty, provide the optimal online route choice in a transit network by balancing the objectives of maximizing on-time arrival probability and minimizing expected travel time. Our framework takes into account the correlation between travel time of different edges along a route and updates downstream distributions by taking advantage of upstream real-time information. We demonstrate the utility and performance of our algorithm with the help of realistic numerical experiments conducted on a fixed-route bus system that serves the residents of the Champaign-Urbana metropolitan area.</p>","PeriodicalId":93224,"journal":{"name":"Proceedings. IEEE Conference on Intelligent Transportation Systems","volume":"2020 ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7840083/pdf/nihms-1609578.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"38873058","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}