{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,31]],"date-time":"2026-03-31T08:34:20Z","timestamp":1774946060975,"version":"3.50.1"},"reference-count":47,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2019,3,30]],"date-time":"2019-03-30T00:00:00Z","timestamp":1553904000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100000140","name":"US Department of Transportation","doi-asserted-by":"publisher","award":["Project No. 17STUNM02"],"award-info":[{"award-number":["Project No. 17STUNM02"]}],"id":[{"id":"10.13039\/100000140","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Currently, over half of the U.S.\u2019s railroad bridges are more than 100 years old. Railroad managers ensure that the proper Maintenance, Repair, and Replacement (MRR) of rail infrastructure is prioritized to safely adapt to the increasing traffic demand. By 2035, the demand for U.S. railroad transportation will increase by 88%, which indicates that considerable expenditure is necessary to upgrade rail infrastructure. Railroad bridge managers need to use their limited funds for bridge MRR to make informed decisions about safety. Consequently, they require economical and reliable methods to receive objective data about bridge displacements under service loads. Current methods of measuring displacements are often expensive. Wired sensors, such as Linear Variable Differential Transformers (LVDTs), require time-consuming installation and involve high labor and maintenance costs. Wireless sensors (WS) are easier to install and maintain but are in general technologically complex and costly. This paper summarizes the development and validation of LEWIS2, the second version of the real-time, low-cost, efficient wireless intelligent sensor (LEWIS) for measuring and autonomously storing reference-free total transverse displacements. The new features of LEWIS2 include portability, accuracy, cost-effectiveness, and readiness for field application. This research evaluates the effectiveness of LEWIS2 for measuring displacements through a series of laboratory experiments. The experiments demonstrate that LEWIS2 can accurately estimate reference-free total displacements, with a maximum error of only 11% in comparison with the LVDT, while it costs less than 5% of the average price of commercial wireless sensors.<\/jats:p>","DOI":"10.3390\/s19071549","type":"journal-article","created":{"date-parts":[[2019,4,2]],"date-time":"2019-04-02T03:21:26Z","timestamp":1554175286000},"page":"1549","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":22,"title":["Measuring Reference-Free Total Displacements of Piles and Columns Using Low-Cost, Battery-Powered, Efficient Wireless Intelligent Sensors (LEWIS2)"],"prefix":"10.3390","volume":"19","author":[{"given":"Marlon","family":"Aguero","sequence":"first","affiliation":[{"name":"Department of Civil, Construction and Environmental Engineering, University of New Mexico, Albuquerque, NM 87131, USA"}]},{"given":"Ali","family":"Ozdagli","sequence":"additional","affiliation":[{"name":"Department of Civil, Construction and Environmental Engineering, University of New Mexico, Albuquerque, NM 87131, USA"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7105-7843","authenticated-orcid":false,"given":"Fernando","family":"Moreu","sequence":"additional","affiliation":[{"name":"Department of Civil, Construction and Environmental Engineering, University of New Mexico, Albuquerque, NM 87131, USA"}]}],"member":"1968","published-online":{"date-parts":[[2019,3,30]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"389","DOI":"10.1080\/15732471003594427","article-title":"Life-Cycle performance, management, and optimisation of structural systems under uncertainty: Accomplishments and challenges","volume":"7","author":"Frangopol","year":"2011","journal-title":"Struct. 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