Abstract
Abstract. The civil engineering and construction sector, including the railway industry, is seeking innovative approaches to reduce costs on repetitive and labour-intensive tasks and avoid the use of highly qualified staff for simple manual duties. Such tasks can include the visual inspection of tunnels, where the process is still dominated by manual operations. Our work compares Close Range Photogrammetry (CRP) and Terrestrial Laser Scanning (TLS), both performed with low-end sensors to reflect the industry’s tendency towards easy to use and easy to maintain hardware. It also analyses the benefits of substituting conventional visual inspections of tunnels with automated survey approaches and computer vision techniques. The project’s outcomes suggest that photogrammetry is a valid alternative to laser scanning for visual inspection of concrete segmentally lined tunnels: from the geometric point of view it provides global accuracy at comparable level to laser scanning, in addition it halves the time to generate the 3D model and provides the user with photo-realistic outputs. It is generally more versatile and it is easier to inspect, visualise and navigate the data. The authors argue that the results presented here will push tunnel inspection in the direction of automated approaches with direct benefits on surveying costs as well as Health & Safety (H&S). Utilising available technology supports risk-based asset management and thus ensures safe and operational performance of a railway for passengers to use.
Highlights
While civil structures are usually designed to last for a specified life-span (Brian, 1997, Gulvanessian, 2009), most tunnels are designed for an indefinite design working life (McKibbins et al, 2009)
A strict schedule of inspections is demanded with intervals between consecutive visits depending on the required Level of Details (LoD) (McKibbins et al, 2009)
Visual inspections is still dominated by manual operations implicating inspectors working at night in potentially elevated health and safety risk conditions
Summary
While civil structures are usually designed to last for a specified life-span (Brian, 1997, Gulvanessian, 2009), most tunnels are designed for an indefinite design working life (McKibbins et al, 2009). Visual inspections is still dominated by manual operations implicating inspectors working at night in potentially elevated health and safety risk conditions. To reduce costs of repetitive and labour-intensive tasks and avoid the use of highly qualified staff for simple manual duties. This will allow to perform inspections with high LoD more frequently, providing the general public with the trust in safe and reliable infrastructure and causing less disruptions;. To reduce the time spent on site to collect data. This would improve H&S conditions considering the numerous hazards operators are exposed to in tunnels
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