Digital twinning of existing reinforced concrete bridges from labelled point clusters

The automation of digital twinning for existing reinforced concrete bridges from point clouds remains an unresolved problem. Whilst current methods can automatically detect bridge objects in point clouds in the form of labelled point clusters, the fitting of accurate 3D shapes to point clusters remains largely human dependent largely. 95% of the total manual modelling time is spent on customizing shapes and fitting them correctly. The challenges exhibited in the fitting step are due to the irregular geometries of existing bridges. Existing methods can fit geometric primitives such as cuboids and cylinders to point clusters, assuming bridges are comprised of generic shapes. However, the produced geometric digital twins are too ideal to depict the real geometry of bridges. In addition, none of the existing methods have explicitly demonstrated how to evaluate the resulting Industry Foundation Classes bridge data models in terms of spatial accuracy using quantitative measurements. In this article, we tackle these challenges by delivering a slicing-based object fitting method that can generate the geometric digital twin of an existing reinforced concrete bridge from four types of labelled point cluster. The quality of the generated models is gauged using cloud-to-cloud distance-based metrics. Experiments on ten bridge point cloud datasets indicate that the method achieves an average modelling distance of 7.05 cm (while the manual method achieves 7.69 cm), and an average modelling time of 37.8 seconds. This is a huge leap over the current practice of digital twinning performed manually

A benchmark framework of geometric digital twinning for slab and beam-slab bridges

We devise, implement, and benchmark a framework LUKIS to automate the process of geometric digital twinning for existing slab and beam-and-slab bridges. LUKIS follows a top-down strategy to detect and twin bridge concrete elements in point clouds into an established data format Industry Foundation Classes. Existing software packages require modellers to spend many labour hours in generating shapes to fit point cloud sub-parts. Previous methods can generate surface primitives combined with rule-based classification to produce cuboid and cylinder models. While these methods work well in synthetic datasets or simplified cases, they encounter challenges when dealing with real-world point clouds. We tackle this challenge by investigating the entire workflow of geometric digital twinning for bridges and proposing LUKIS to auto-generate bridge objects without needing to generate low-level surface primitives. We implement LUKIS on a single software platform. Experiments demonstrate its ability to rapidly twin geometric bridge concrete elements. Compared to manual operation, LUKIS reduces the overall twinning time by at least 95.4% while the twinning quality (spatial accuracy) is improved. It is the first framework of its kind to achieve the geometric digital twinning for primary concrete elements of bridges on one platform. It lays foundations for researchers to generate semantically enriched digital twins

Generating bridge geometric digital twins from point clouds

The automation of digital twinning for existing bridges from point clouds remains unresolved. Previous research yielded methods that can generate surface primitives combined with rule-based classification to create labelled cuboids and cylinders. While these methods work well in synthetic datasets or simplified cases, they encounter huge challenges when dealing with real-world point clouds. The proposed framework employs bridge engineering knowledge that mimics the intelligence of human modellers to detect and model reinforced concrete bridge objects in imperfect point clouds. Experiments on ten bridge point clouds indicate the framework can achieve high and reliable performance of geometric digital twin generation of existing bridges.This research is funded by EPSRC, EU Infravation SeeBridge project under Grant No. 31109806.0007 and Trimble Research Fun

Detection of Structural Components in Point Clouds of Existing RC Bridges

The cost and effort of modelling existing bridges from point clouds currently outweighs the perceived benefits of the resulting model. There is a pressing need to automate this process. Previous research has achieved the automatic generation of surface primitives combined with rule-based classification to create labelled cuboids and cylinders from point clouds. While these methods work well in synthetic datasets or idealized cases, they encounter huge challenges when dealing with real-world bridge point clouds, which are often unevenly distributed and suffer from occlusions. In addition, real bridge geometries are complicated. In this paper, we propose a novel top-down method to tackle these challenges for detecting slab, pier, pier cap, and girder components in reinforced concrete bridges. This method uses a slicing algorithm to separate the deck assembly from pier assemblies. It then detects and segments pier caps using their surface normal, and girders using oriented bounding boxes and density histograms. Finally, our method merges over-segments into individually labelled point clusters. The results of 10 real-world bridge point cloud experiments indicate that our method achieves very high detection performance. This is the first method of its kind to achieve robust detection performance for the four component types in reinforced concrete bridges and to directly produce labelled point clusters. Our work provides a solid foundation for future work in generating rich Industry Foundation Classes models from the labelled point clusters

Generating bridge geometric digital twins from point clouds

The automation of digital twinning for existing bridges from point clouds remains unsolved. Extensive manual effort is required to extract object point clusters from point clouds followed by fitting them with accurate 3D shapes. Previous research yielded methods that can automatically generate surface primitives combined with rule-based classification to create labelled cuboids and cylinders. While these methods work well in synthetic datasets or simplified cases, they encounter huge challenges when dealing with realworld point clouds. In addition, bridge geometries, defined with curved alignments and varying elevations, are much more complicated than idealized cases. None of the existing methods can handle these difficulties reliably. The proposed framework employs bridge engineering knowledge that mimics the intelligence of human modellers to detect and model reinforced concrete bridge objects in imperfect point clouds. It directly produces labelled 3D objects in Industry Foundation Classes format without generating low-level shape primitives. Experiments on ten bridge point clouds indicate the framework achieves an overall detection F1-score of 98.4%, an average modelling accuracy of 7.05 cm, and an average modelling time of merely 37.8 seconds. This is the first framework of its kind to achieve high and reliable performance of geometric digital twin generation of existing bridges

Digital twinning of existing bridges from labelled point clusters

The automation of digital twinning for existing bridges from point clouds has yet been solved. Whilst current methods can automatically detect bridge objects in points clouds in the form of labelled point clusters, the fitting of accurate 3D shapes to detected point clusters remains human dependent to a great extent. 95% of the total manual modelling time is spent on customizing shapes and fitting them to right locations. The challenges exhibited in the fitting step are due to the irregular geometries of existing bridges. Existing methods can fit geometric primitives such as cuboids and cylinders to point clusters, assuming bridges are made up of generic shapes. However, the produced geometric digital twins are too ideal to depict the real geometry of bridges. In addition, none of existing methods have evaluated the resulting models in terms of spatial accuracy with quantitative measurements. We tackle these challenges by delivering a slicing-based object fitting method that can generate the geometric digital twin of an existing reinforced concrete bridge from labelled point clusters. The accuracy of the generated models is gauged using distance-based metrics. Experiments on ten bridge point clouds indicate that the method achieves an average modelling distance smaller than that of the manual one (7.05 cm vs. 7.69 cm) (value included all challenging cases), and an average twinning time of 37.8 seconds. Compared to the laborious manual practice, this is much faster to twin bridge concrete elements

Construction health and safety: A topic landscape study

We aim to draw in-depth insights into the current literature in construction health and safety and provide perspectives for future research efforts. The existing literature on construction health and safety is not only diverse and rich in sight, but also complex and fragmented in structure. It is essential for the construction industry and research community to understand the overall development and existing challenges of construction health and safety to adapt to future new code of practice and challenges in this field. We mapped the topic landscape followed by identifying the salient development trajectories of this research area over time. We used the topic modeling algorithm to extract 10 distinct topics from 662 abstracts (filtered from a total of 895) of articles published between 1991 and 2020. In addition, we provided the most cited references and the most popular journal per topic as well. The results from a time series analysis suggested that the construction health and safety would maintain its popularity in the next 5 years. Research efforts would be devoted to the topics including “Physical health and disease”, “Migrant and race”, “Vocational ability and training”, and “Smart devices.” Among these topics, “Smart devices” would be the most promising one

A benchmark framework of geometric digital twinning for slab and beam-slab bridges

We devise, implement, and benchmark a framework LUKIS to automate the process of geometric digital twinning for existing slab and beam-and-slab bridges. LUKIS follows a top-down strategy to detect and twin bridge concrete elements in point clouds into an established data format Industry Foundation Classes. Existing software packages require modellers to spend many labour hours in generating shapes to fit point cloud sub-parts. Previous methods can generate surface primitives combined with rule-based classification to produce cuboid and cylinder models. While these methods work well in synthetic datasets or simplified cases, they encounter challenges when dealing with real-world point clouds. We tackle this challenge by investigating the entire workflow of geometric digital twinning for bridges and proposing LUKIS to auto-generate bridge objects without needing to generate low-level surface primitives. We implement LUKIS on a single software platform. Experiments demonstrate its ability to rapidly twin geometric bridge concrete elements. Compared to manual operation, LUKIS reduces the overall twinning time by at least 95.4% while the twinning quality (spatial accuracy) is improved. It is the first framework of its kind to achieve the geometric digital twinning for primary concrete elements of bridges on one platform. It lays foundations for researchers to generate semantically enriched digital twins.Cambridge Trimble Fun

Challenges of bridge maintenance inspection

Bridges are amongst the largest, most expensive and complex structures, which makes them crucial and valuable transportation asset for modern infrastructure. Bridge inspection is a crucial component of monitoring and maintaining these complex structures. It provides a safety assessment and condition documentation on a regular basis, noting maintenance actions needed to counteract defects like cracks, corrosion and spalling. This paper presents the challenges with existing bridge maintenance inspection as well as an overview on proposed methods to overcome these challenges by automating inspection using computer vision methods. As a conclusion, existing methods for automated bridge inspection are able to detect one class of damage type based on images. A multiclass approach that also considers the 3D geometry, as inspectors do, is missing

Detection of key components of existing bridge in point cloud datasets

The cost and effort for modelling existing bridges from point clouds currently outweighs the perceived benefits of the resulting model. Automating the point cloud-to-Bridge Information Models process can drastically reduce the manual effort and cost involved. Previous research has achieved the automatic generation of surfaces primitives combined with rule-based classification to create labelled construction models from point clouds. These methods work very well in synthetic dataset or idealized cases. However, real bridge point clouds are often incomplete, and contain unevenly distributed points. Also, bridge geometries are complex. They are defined with horizontal alignments, vertical elevations and cross-sections. These characteristics are the reasons behind the performance issues existing methods have in real datasets. We propose to tackle this challenge via a novel top-down method for major bridge component detection in this paper. Our method bypasses the surface generation process altogether. Firstly, this method uses a slicing algorithm to separate deck assembly from pier assemblies. It then detects pier caps using their surface normal, and uses oriented bounding boxes and density histograms to segment the girders. Finally, the method terminates by merging over-segments into individual labelled point clusters. Experimental results indicate an average detection precision of 99.2%, recall of 98.3%, and F1-score of 98.7%. This is the first method to achieve reliable detection performance in real bridge datasets. This sets a solid foundation for researchers attempting to derive rich IFC (Industry Foundation Classes) models from individual point clusters