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Digital Point Clouds Support Risk Assessment for Historic Stone Bridges
A new study presents a digital framework for assessing risk and sustainability in historic stone bridges using terrestrial laser scanning point clouds. The research focuses on a key challenge in heritage management: many historic bridges still serve modern infrastructure needs while also carrying cultural and architectural value, making their conservation both technically and socially important.
The proposed method uses point-cloud data directly, without first converting it into BIM or HBIM models. This is important because detailed digital modelling can be time-consuming and may require resources or expertise that are not always available in early-stage heritage assessments. Instead, the study treats the point cloud itself as the main analytical source.
The framework was tested on the Stone Bridge in Băile Herculane, Romania, a 19th-century masonry bridge built around 1864. The bridge is an important architectural landmark in the Cerna Valley and remains connected to the historic urban landscape of the area. It is built mainly of stone and brick and includes two vaulted spans, covered footpaths, and decorative metal elements.
Researchers documented the bridge using terrestrial laser scanning from 17 scan stations. The raw dataset contained more than 177 million points, which was later cleaned and reduced to about 81 million points representing the bridge structure. The data were then analysed in CloudCompare, while numerical processing and risk scoring were completed in Excel.
The study extracted five geometric indicators from the point cloud. These included surface roughness, point density, low-coverage areas, roughness hotspots, and visible geometric discontinuities. These indicators were not treated as direct proof of damage, but as proxies that may point to surface weathering, inspection uncertainty, localized degradation, or safety-related irregularities.
The results showed generally limited material degradation, but also localized roughness hotspots and significant areas of low scan coverage. The low-coverage ratio reached 42.34%, indicating that some parts of the structure, especially shadowed or hard-to-access areas, require further inspection. Local deck discontinuities of about 20–30 mm were also identified, suggesting potential serviceability or safety concerns.
The study then translated these indicators into a simplified risk framework based on probability and severity. The highest-ranked concerns were inspection uncertainty, maintenance planning reliability, and localized deck discontinuities. These were connected to environmental, economic, and social sustainability dimensions.
Overall, the research shows that point-cloud analysis can provide useful early-stage information for heritage bridge management without requiring full digital modelling. The authors note that the method does not replace structural analysis, material testing, or direct inspection, but it can help prioritize where more detailed assessment is needed.
Published on: 04-06-2026
Edited by: Abdulmnam Samakie
Source: npj Heritage Science
