Wharves are constructed with concrete elements that are subject to corrosion, and maintenance is key for their continued use. With challenging factors such as tide and low visibility, many surveyors are turning to photogrammetry to inspect underneath wharves.
The challenges of physical wharf inspections
With hundreds of metres of the wharf structure to look at, and a race against time to conduct the inspection, it can be difficult for surveyors to correctly record and report the location of defects. Typically, generalised reporting occurs over larger parts of the wharf and can result in less accuracy.
In addition to defects being missed, surveyors must also factor in:
Limited access space: Constrained space between the underside of the wharf and the water's surface. This restricted area makes it difficult for personnel to physically access and inspect the underside of the structure.
Tidal and Swell Variations: Inspections must be timed carefully to account for tidal changes and swell conditions.
GPS Denied Environment: The area under wharfs often lacks GPS signal, making it challenging to track the location accurately during inspections. This can affect the precision of data collection and the ability to create accurate 3D models.
Low Light Conditions: Underneath wharfs, there is limited natural light, which can result in dark and poorly lit environments. This can lead to high ISO settings on cameras, resulting in noisy or grainy images that may affect the quality of inspection data.
Corrosion and Saltwater Exposure: Wharfs are exposed to saltwater, which can lead to corrosion of concrete elements. Inspecting for chloride content and corrosion risks in such an environment requires specialized equipment and expertise.
Structural Complexity: Wharfs can have intricate structural designs with various support elements and features that need to be thoroughly examined. Navigating and inspecting these complex structures can be challenging.
What is photogrammetry, and how does it help?
Photogrammetry is the process of collecting reliable information about a physical object or environment by recording, measuring, and interpreting imagery and sensor data such as photography, GPS and thermal.
Trendspek, a 3D asset management software, processes this photogrammetry data into a Precision Reality Twin – an exact 3D replica that can be viewed, interacted with and marked up via computer.
By marking up directly onto the 3D model, this allows surveyors and engineers to complete comprehensive condition assessments without needing to physically go underneath a wharf.
Capturing data underneath a wharf
Hoverscape's Chief Remote Pilot Danny Elassad shares his tips for capturing photogrammetry underneath a wharf:
1. Integrated Data Capture: We start with an integrated capture survey of the entire wharf structure. High-resolution imagery and videos captured from above can provide an overview of the entire area and identify potential problem areas.
To inspect the underside of the wharf, we use a low-lying boat (like a tinny) to navigate the tight spaces beneath the structure. We equip the boat with cameras, sensors, and GPS equipment.
These devices will capture high-quality imagery and spatial data.
2. Data Processing and 3D Modelling: Once we’ve collected the data, including images and spatial information, this can be processed into a high-fidelity 3D Precision Reality Twin in Trendspek’s software to create an exact replica of the entire under-wharf area. The integration of GPS data ensures accurate georeferencing of the model.
3. Chloride and Corrosion Analysis: Once the 3D model is created, asset owners and engineers can conduct a detailed inspection of the wharf’s structural elements on-screen, including support columns, beams, and any potential signs of deterioation or corrosion damage to the concrete. This analysis can help identify areas that require maintenance or repair.
4. Tying with Aerial Data: We can combine the under-wharf 3D model with the above-deck drone data captured in the initial aerial survey. This integrated approach provides a comprehensive view of the entire wharf structure, both above and below the waterline.
5. Asset Management and Reporting: Asset owners can retrospectively refer to the inspection data to create reports that highlight maintenance priorities and recommendations. This information can aid in informed decision-making for asset management and repair strategies.
Trendspek Precision Reality Twins can be used for WSCAM compliance
By using software like Trendspek, inspectors can conduct accurate assessments of a wharf's condition and proactively plan maintenance ahead of time.
Trendspek's customisable fields also allow asset owners to set templates to meet WSCAM criteria, from condition scaling to colour-coded outcomes.
Read more about how you can use Trendspek to achieve WSCAM compliance here.
