{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,12]],"date-time":"2026-10-12T23:55:10Z","timestamp":1791849310847,"version":"4.3.4"},"reference-count":21,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2026,2,19]],"date-time":"2026-02-19T00:00:00Z","timestamp":1771459200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"the Chongqing Technical Innovation and Application Development Special Key Project","award":["CSTB2022TIAD-KPX0137"],"award-info":[{"award-number":["CSTB2022TIAD-KPX0137"]}]},{"name":"the National Key Research and Development Program of China","award":["SQ2024YFC3800232"],"award-info":[{"award-number":["SQ2024YFC3800232"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Fall-from-height fatalities in underground construction are closely associated with formwork scaffold operations, where dense steel members cause severe non-line-of-sight (NLOS) and multipath effects that degrade positioning performance. Although ultra-wideband (UWB) technology offers high theoretical ranging accuracy, its deployment-dependent performance in metal-rich scaffold environments remains insufficiently quantified. This study focuses on physical deployment optimization rather than algorithmic compensation. A full-scale formwork scaffold was constructed, and a stepwise one-factor controlled experimental design was employed to quantify the effects of anchor height (H) and horizontal spacing (S) on 3D positioning accuracy. The results show that sub-meter accuracy can be achieved through appropriate deployment, with a minimum 3D RMSE of 0.317 m and over 80% of single-axis errors confined within a 0.2 m engineering-valid region. For this specific setup, the optimal S = 1.5 m correlates with the scaffold grid size (approximately 0.8 times the 1.8 m bay width). While we hypothesize this ratio dependency applies to other geometries, this remains a site-specific observation requiring future cross-validation. Further analysis indicates that this deployment balances vertical signal visibility and multipath suppression. In addition, while the Position Dilution of Precision (PDOP) metric reflects geometric sensitivity, it does not linearly correlate with actual positioning errors under coplanar UWB deployments. These findings provide a rigorous static error model, serving as a critical prerequisite for developing robust real-time safety monitoring systems in scaffold-intensive construction environments.<\/jats:p>","DOI":"10.3390\/s26041340","type":"journal-article","created":{"date-parts":[[2026,2,19]],"date-time":"2026-02-19T15:57:29Z","timestamp":1771516649000},"page":"1340","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Optimization of UWB Base Station Deployment for Formwork Scaffolds in Underground Construction with Sub-Meter Positioning Accuracy by Semi-Controlled Field Experiments"],"prefix":"10.3390","volume":"26","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-6027-3367","authenticated-orcid":false,"given":"Gang","family":"Yao","sequence":"first","affiliation":[{"name":"School of Civil Engineering, Chongqing University, Chongqing 400045, China"},{"name":"State Key Laboratory of Safety and Resilience of Civil Engineering in Mountain Area, Chongqing 400045, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lang","family":"Liu","sequence":"additional","affiliation":[{"name":"School of Civil Engineering, Chongqing University, Chongqing 400045, China"},{"name":"State Key Laboratory of Safety and Resilience of Civil Engineering in Mountain Area, Chongqing 400045, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1154-0112","authenticated-orcid":false,"given":"Yang","family":"Yang","sequence":"additional","affiliation":[{"name":"School of Civil Engineering, Chongqing University, Chongqing 400045, China"},{"name":"State Key Laboratory of Safety and Resilience of Civil Engineering in Mountain Area, Chongqing 400045, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0006-1391-6474","authenticated-orcid":false,"given":"Xiaodong","family":"Cai","sequence":"additional","affiliation":[{"name":"School of Civil Engineering, Chongqing University, Chongqing 400045, China"},{"name":"State Key Laboratory of Safety and Resilience of Civil Engineering in Mountain Area, Chongqing 400045, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xin","family":"Yang","sequence":"additional","affiliation":[{"name":"School of Civil Engineering, Chongqing University, Chongqing 400045, China"},{"name":"State Key Laboratory of Safety and Resilience of Civil Engineering in Mountain Area, Chongqing 400045, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Huiwen","family":"Hou","sequence":"additional","affiliation":[{"name":"School of Civil Engineering, Chongqing University, Chongqing 400045, China"},{"name":"State Key Laboratory of Safety and Resilience of Civil Engineering in Mountain Area, Chongqing 400045, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mingpu","family":"Wang","sequence":"additional","affiliation":[{"name":"Department of Civil Engineering, Tsinghua University, Beijing 100084, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Pengcheng","family":"Li","sequence":"additional","affiliation":[{"name":"School of Civil Engineering, Chongqing University, Chongqing 400045, China"},{"name":"State Key Laboratory of Safety and Resilience of Civil Engineering in Mountain Area, Chongqing 400045, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,2,19]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Pereira, F., Gonz\u00e1lez Garc\u00eda, M.D.L.N., and Po\u00e7as Martins, J. (2024). An Evaluation of the Technologies Used for the Real-Time Monitoring of the Risk of Falling from Height in Construction\u2014Systematic Review. Buildings, 14.","DOI":"10.3390\/buildings14092879"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"111527","DOI":"10.1016\/j.comnet.2025.111527","article-title":"A comparative analysis of indoor localization technologies","volume":"270","author":"Roohi","year":"2025","journal-title":"Comput. Netw."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"115","DOI":"10.12677\/JEE.2021.93013","article-title":"Application of UWB Positioning Technology in 500 kV Substation","volume":"9","author":"Cui","year":"2021","journal-title":"J. Electr. Eng."},{"key":"ref_4","unstructured":"Chen, L., and Wu, T. (2020). Intelligent Risk Management of Bridge Construction Personnel and Vehicles. J. Civ. Eng. Manag. (Tumu Gongcheng Yu Guanli Xuebao), 37."},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Alarifi, A., Al-Salman, A., Alsaleh, M., Alnafessah, A., Al-Hadhrami, S., Al-Ammar, M., and Al-Khalifa, H. (2016). Ultra Wideband Indoor Positioning Technologies: Analysis and Recent Advances. Sensors, 16.","DOI":"10.3390\/s16050707"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"4575","DOI":"10.1007\/s12205-024-2107-z","article-title":"A Study on Anchor Placement and 3D Positioning Algorithm for UWB Application in Small Sites","volume":"28","author":"Cho","year":"2024","journal-title":"KSCE J. Civ. Eng."},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"Xu, S., Liu, Q., Lin, M., Wang, Q., and Chen, K. (2025). A Double Extended Kalman Filter Algorithm for Weakening Non-Line-of-Sight Errors in Complex Indoor Environments Based on Ultra-Wideband Technology. Sensors, 25.","DOI":"10.3390\/s25030740"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"117721","DOI":"10.1016\/j.measurement.2025.117721","article-title":"A novel credibility evaluation and mitigation for ranging measurement in UWB localization","volume":"256","author":"Yang","year":"2025","journal-title":"Measurement"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"229","DOI":"10.1016\/j.ssci.2019.04.025","article-title":"Real-time locating systems and safety in construction sites: A literature review","volume":"117","author":"Soltanmohammadlou","year":"2019","journal-title":"Saf. Sci."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"100164","DOI":"10.1016\/j.kscej.2025.100164","article-title":"Real-time indoor localization and safety applications using UWB in construction","volume":"29","author":"Cho","year":"2025","journal-title":"KSCE J. Civ. Eng."},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Umer, W., and Siddiqui, M.K. (2020). Use of Ultra Wide Band Real-Time Location System on Construction Jobsites: Feasibility Study and Deployment Alternatives. Int. J. Environ. Res. Public Health, 17.","DOI":"10.3390\/ijerph17072219"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"046302","DOI":"10.1088\/1361-6501\/adbb10","article-title":"Application of variational Bayesian-based cubature information filter for UWB\/INS tightly coupled positioning system","volume":"36","author":"Wang","year":"2025","journal-title":"Meas. Sci. Technol."},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Kramari\u0107, L., Mu\u0161tra, M., and Radi\u0161i\u0107, T. (2025). The Influence of Ultra-Wideband Anchor Placement on Localization Accuracy. Sensors, 25.","DOI":"10.20944\/preprints202506.1667.v1"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"124808","DOI":"10.1016\/j.eswa.2024.124808","article-title":"Optimal layout of four anchors to improve accuracy of Ultra-Wide band based indoor positioning","volume":"255","author":"Cho","year":"2024","journal-title":"Expert Syst. Appl."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"108056","DOI":"10.1016\/j.measurement.2020.108056","article-title":"A study on the optimization nodes arrangement in UWB localization","volume":"163","author":"Wang","year":"2020","journal-title":"Measurement"},{"key":"ref_16","doi-asserted-by":"crossref","unstructured":"Hu, H., Yang, X., Liu, R., Liu, L., and Hu, H. (2024). Study on the Deployment of Ultra-Wideband Positioning Base Stations in Pig Farms. Appl. Sci., 14.","DOI":"10.3390\/app14020501"},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"\u00c1lvarez-Merino, C.S., Khatib, E.J., Luo-Chen, H.Q., Michel, J.L., Casalderrey-D\u00edaz, S., Alonso, J., and Barco, R. (2022). WiFi FTM and UWB Characterization for Localization in Construction Sites. Sensors, 22.","DOI":"10.3390\/s22145373"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"22","DOI":"10.1049\/wss2.12006","article-title":"Anchor selection by geometric dilution of precision for an indoor positioning system using ultra-wide band technology","volume":"11","author":"Albaidhani","year":"2021","journal-title":"IET Wirel. Sens. Syst."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"17985","DOI":"10.1038\/s41598-024-68998-0","article-title":"Optimization of UWB indoor positioning based on hardware accelerated Fuzzy ISODATA","volume":"14","author":"Guo","year":"2024","journal-title":"Sci. Rep."},{"key":"ref_20","first-page":"1","article-title":"Positioning Performance Analysis of Indoor Networks of Range-Based Reference Stations","volume":"50","author":"Li","year":"2025","journal-title":"Geomat. Inf. Sci. Wuhan Univ."},{"key":"ref_21","unstructured":"(2016). Technical Code for Safety of Working at Height of Building Construction (Standard No. JGJ 80-2016)."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/26\/4\/1340\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,2,25]],"date-time":"2026-02-25T05:22:46Z","timestamp":1771996966000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/26\/4\/1340"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,2,19]]},"references-count":21,"journal-issue":{"issue":"4","published-online":{"date-parts":[[2026,2]]}},"alternative-id":["s26041340"],"URL":"https:\/\/doi.org\/10.3390\/s26041340","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,2,19]]}}}