{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,24]],"date-time":"2026-08-24T12:26:25Z","timestamp":1787574385978,"version":"build-2736575974"},"reference-count":94,"publisher":"MDPI AG","issue":"17","license":[{"start":{"date-parts":[[2026,8,23]],"date-time":"2026-08-23T00:00:00Z","timestamp":1787443200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Open Fund Project for the State Key Laboratory of Spatial Datum","award":["SKLGIE2024-Z-3-1"],"award-info":[{"award-number":["SKLGIE2024-Z-3-1"]}]},{"name":"Postgraduate Research & Practice Innovation Program of Jiangsu Province","award":["KYCX25_0712"],"award-info":[{"award-number":["KYCX25_0712"]}]},{"name":"Jiangsu Funding Program for Excellent Postdoctoral Talent","award":["2024ZB688"],"award-info":[{"award-number":["2024ZB688"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>As urban underground spaces and infrastructure development accelerate, subsurface elements such as buried pipelines, integrated utility tunnels, subway tunnels, cavity defects, and deep-seated hidden hazards become increasingly intertwined. Consequently, urban target detection is characterized by pronounced scale discrepancies, intense environmental interference, and severely confined operational spaces. The transient electromagnetic method (TEM) is highly valuable for rapid surveys and hazard identification in urban underground spaces owing to its inherent advantages, including non-contact operation, adaptability to hardened pavements, high sensitivity to low-resistivity anomalies, and the ability to probe a broad range of depths. In recent years, research has shifted from improving isolated instrumentation to synergistically optimizing sensing platforms, transmitter\u2013receiver systems, anti-interference methodologies, and imaging interpretation workflows. Specifically, small-loop configurations and high-frequency excitation technologies have improved shallow-sounding capabilities in confined urban spaces; anti-interference techniques have increased data reliability in complex noise environments; and apparent resistivity mapping, virtual wave-field migration, and rapid inversion methodologies have enabled profiling results to transition from qualitative identification to fine-scale interpretation. Concurrently, the evolution of ground-towed, UAV-borne, helicopter-borne, and semi-airborne platforms has progressively endowed urban TEM profiling with continuous, mobile, and scenario-specific operational capabilities. Looking to the future, further technical breakthroughs in urban TEM technology are required to improve shallow-resolution, deep-seated penetration, multi-source interference decoupling, and real-time concurrent imaging.<\/jats:p>","DOI":"10.3390\/s26175339","type":"journal-article","created":{"date-parts":[[2026,8,24]],"date-time":"2026-08-24T11:47:19Z","timestamp":1787572039000},"page":"5339","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Sensing Platform Technologies of the Transient Electromagnetic Method for Urban Underground Space Detection: Challenges and Advances"],"prefix":"10.3390","volume":"26","author":[{"given":"Hanlin","family":"Guo","sequence":"first","affiliation":[{"name":"State Key Laboratory of Spatial Datum, Xi\u2019an 710054, China"},{"name":"School of Safety Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Qiyan","family":"Gu","sequence":"additional","affiliation":[{"name":"School of Safety Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jian","family":"Xu","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Spatial Datum, Xi\u2019an 710054, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Haotian","family":"Shi","sequence":"additional","affiliation":[{"name":"School of Safety Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8248-586X","authenticated-orcid":false,"given":"Leixiang","family":"Bian","sequence":"additional","affiliation":[{"name":"School of Safety Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1224-9789","authenticated-orcid":false,"given":"Zhan","family":"Xu","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Spatial Datum, Xi\u2019an 710054, China"},{"name":"School of Safety Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,8,23]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"2622","DOI":"10.1109\/TII.2021.3104012","article-title":"Rapid and High-Resolution Detection of Urban Underground Space Using Transient Electromagnetic Method","volume":"18","author":"Lin","year":"2022","journal-title":"IEEE Trans. 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