{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,7]],"date-time":"2026-02-07T19:20:06Z","timestamp":1770492006204,"version":"3.49.0"},"reference-count":27,"publisher":"MDPI AG","issue":"6","license":[{"start":{"date-parts":[[2021,3,17]],"date-time":"2021-03-17T00:00:00Z","timestamp":1615939200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100014440","name":"Ministerio de Ciencia, Innovaci\u00f3n y Universidades","doi-asserted-by":"publisher","award":["RTI2018-096384-B-I00"],"award-info":[{"award-number":["RTI2018-096384-B-I00"]}],"id":[{"id":"10.13039\/100014440","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Riding a bicycle is a great manner to contribute to the preservation of our ecosystem. Cycling helps to reduce air pollution and traffic congestion, and so, it is one of the simplest ways to lower the environmental footprint of people. However, the cohabitation of cars and vulnerable road users, such as bikes, scooters, or pedestrians, is prone to cause accidents with serious consequences. In this context, technological solutions are sought that enable the generation of alerts to prevent these accidents, thereby promoting a safer city for these road users, and a cleaner environment. Alert systems based on smartphones can alleviate these situations since nearly all people carry such a device while traveling. In this work, we test the suitability of a smartphone based alert system, determining the most adequate communications architecture. Two protocols have been designed to send position and alert messages to\/from a centralized server over 4G cellular networks. One of the protocols is implemented using a REST architecture on top of the HTTP protocol, and the other one is implemented over the UDP protocol. We show that the proposed alarm system is feasible regarding communication response time, and we conclude that the application should be implemented over the UDP protocol, as response times are about three times better than for the REST implementation. We tested the applications in real deployments, finding that drivers are warned of the presence of bicycles when closer than 150 m, having enough time to pay attention to the situation and drive more carefully to avoid a collision.<\/jats:p>","DOI":"10.3390\/s21062116","type":"journal-article","created":{"date-parts":[[2021,3,17]],"date-time":"2021-03-17T21:43:31Z","timestamp":1616017411000},"page":"2116","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":9,"title":["Towards a Sustainable City for Cyclists: Promoting Safety through a Mobile Sensing Application"],"prefix":"10.3390","volume":"21","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-7850-8179","authenticated-orcid":false,"given":"Pablo","family":"Boronat","sequence":"first","affiliation":[{"name":"Computer Languages and Systems Department, Universitat Jaume I (UJI), 12071 Castell\u00f3 de la Plana, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3831-4075","authenticated-orcid":false,"given":"Miguel","family":"P\u00e9rez-Francisco","sequence":"additional","affiliation":[{"name":"Computer Science and Engineering Department, Universitat Jaume I (UJI), 12071 Castell\u00f3 de la Plana, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5729-3041","authenticated-orcid":false,"given":"Carlos T.","family":"Calafate","sequence":"additional","affiliation":[{"name":"Computer Engineering Department (DISCA), Universitat Polit\u00e8cnica de Val\u00e8ncia (UPV), 46022 Valencia, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0038-0539","authenticated-orcid":false,"given":"Juan-Carlos","family":"Cano","sequence":"additional","affiliation":[{"name":"Computer Engineering Department (DISCA), Universitat Polit\u00e8cnica de Val\u00e8ncia (UPV), 46022 Valencia, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2021,3,17]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"11076","DOI":"10.3390\/en81011076","article-title":"An Integrated Environmental Indicator for Urban Transportation Systems: Description and Application","volume":"8","author":"Gennusa","year":"2015","journal-title":"Energies"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"1284","DOI":"10.1158\/1055-9965.EPI-10-0036","article-title":"Air pollution from traffic and risk for lung cancer in three Danish cohorts","volume":"19","author":"Bak","year":"2010","journal-title":"Cancer Epidemiol. 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