{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,30]],"date-time":"2026-04-30T19:09:01Z","timestamp":1777576141247,"version":"3.51.4"},"reference-count":57,"publisher":"MDPI AG","issue":"21","license":[{"start":{"date-parts":[[2020,10,24]],"date-time":"2020-10-24T00:00:00Z","timestamp":1603497600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100000209","name":"National Academy of Sciences","doi-asserted-by":"publisher","award":["160416-0399"],"award-info":[{"award-number":["160416-0399"]}],"id":[{"id":"10.13039\/100000209","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100000209","name":"National Academy of Sciences","doi-asserted-by":"publisher","award":["163418-0399"],"award-info":[{"award-number":["163418-0399"]}],"id":[{"id":"10.13039\/100000209","id-type":"DOI","asserted-by":"publisher"}]},{"name":"New Mexico Consortium","award":["249-01"],"award-info":[{"award-number":["249-01"]}]},{"name":"New Mexico Consortium","award":["A21-0053"],"award-info":[{"award-number":["A21-0053"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Measurement of bridge displacements is important for ensuring the safe operation of railway bridges. Traditionally, contact sensors such as Linear Variable Displacement Transducers (LVDT) and accelerometers have been used to measure the displacement of the railway bridges. However, these sensors need significant effort in installation and maintenance. Therefore, railroad management agencies are interested in new means to measure bridge displacements. This research focuses on mounting Laser Doppler Vibrometer (LDV) on an Unmanned Aerial System (UAS) to enable contact-free transverse dynamic displacement of railroad bridges. Researchers conducted three field tests by flying the Unmanned Aerial Systems Laser Doppler Vibrometer (UAS-LDV) 1.5 m away from the ground and measured the displacement of a moving target at various distances. The accuracy of the UAS-LDV measurements was compared to the Linear Variable Differential Transducer (LVDT) measurements. The results of the three field tests showed that the proposed system could measure non-contact, reference-free dynamic displacement with an average peak and root mean square (RMS) error for the three experiments of 10% and 8% compared to LVDT, respectively. Such errors are acceptable for field measurements in railroads, as the interest prior to bridge monitoring implementation of a new approach is to demonstrate similar success for different flights, as reported in the three results. This study also identified barriers for industrial adoption of this technology and proposed operational development practices for both technical and cost-effective implementation.<\/jats:p>","DOI":"10.3390\/s20216051","type":"journal-article","created":{"date-parts":[[2020,10,26]],"date-time":"2020-10-26T03:51:47Z","timestamp":1603684307000},"page":"6051","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":36,"title":["Measuring Transverse Displacements Using Unmanned Aerial Systems Laser Doppler Vibrometer (UAS-LDV): Development and Field Validation"],"prefix":"10.3390","volume":"20","author":[{"given":"Piyush","family":"Garg","sequence":"first","affiliation":[{"name":"Department of Electrical &amp; Computer Engineering, University of New Mexico, Albuquerque, NM 87131-0001, USA"}]},{"given":"Roya","family":"Nasimi","sequence":"additional","affiliation":[{"name":"Department of Civil, Construction, &amp; Environmental Engineering, University of New Mexico, Albuquerque, NM 87131-0001, USA"}]},{"given":"Ali","family":"Ozdagli","sequence":"additional","affiliation":[{"name":"Department of Civil, Construction, &amp; Environmental Engineering, University of New Mexico, Albuquerque, NM 87131-0001, USA"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0396-2518","authenticated-orcid":false,"given":"Su","family":"Zhang","sequence":"additional","affiliation":[{"name":"Department of Civil, Construction, &amp; Environmental Engineering, University of New Mexico, Albuquerque, NM 87131-0001, USA"},{"name":"Earth Data Analysis Center (EDAC), University of New Mexico, MSC01 1110, 1 University of New Mexico, Albuquerque, NM 87131-0001, USA"}]},{"given":"David Dennis Lee","family":"Mascarenas","sequence":"additional","affiliation":[{"name":"Los Alamos National Laboratory, National Security Education Center (NSEC), Los Alamos National Labs MS-T001, PO Box 1663, Los Alamos, NM 87545, USA"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3707-9336","authenticated-orcid":false,"given":"Mahmoud","family":"Reda Taha","sequence":"additional","affiliation":[{"name":"Department of Civil, Construction, &amp; Environmental Engineering, University of New Mexico, Albuquerque, NM 87131-0001, USA"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7105-7843","authenticated-orcid":false,"given":"Fernando","family":"Moreu","sequence":"additional","affiliation":[{"name":"Department of Civil, Construction, &amp; Environmental Engineering, University of New Mexico, Albuquerque, NM 87131-0001, USA"}]}],"member":"1968","published-online":{"date-parts":[[2020,10,24]]},"reference":[{"key":"ref_1","unstructured":"Federal Railroad Administration (2018, May 22). 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