Improving Bridge Inspection Surveys

With thousands of bridges crossing rivers in the UK, ensuring the integrity of each of these structures is not always a straightforward task.

Even understanding the condition of the bridge can become an obstacle, some of which are in inhospitable or challenging locations. According to New Civil Engineer, more than 3,000 council-managed road bridges have been identified as substandard between February 2019 -2020.

The UK has a long heritage of bridge engineering. The Industrial Revolution placed Britain at the forefront of bridge design globally, and the Victorian period saw a spate of bridge-building, including thousands of railway bridges.

Our ageing assets require more regular monitoring to ensure safety and prolong the lifespan. Skerne Bridge in Darlington is the world's oldest railway bridge in continuous use at 195 years old and was recently the subject of improvement works. There are many factors to consider when it comes to ensuring the integrity of these structures.

Surveying bridges, particularly those in challenging environments like rivers, is crucial for ensuring the structural integrity, safety and longevity of these vital infrastructure assets. This post explores how advancements in technology are transforming bridge surveys, making them more efficient, accurate, and safe.

Skerne Bridge, Darlington, Image Credit: Network Rail

Combined survey dataset

Richmond, North Yorkshire

Bridge survey data example

The Challenges of Surveying Bridge Structures

By their nature, bridges crossing rivers present a challenge to survey and inspect. Firstly, there is the clear fact that a portion of the structure is submerged. Submerged structures are notoriously difficult to inspect due to limited visibility and accessibility. Traditional assessment methods often fall short in providing detailed information, making it hard to detect issues like erosion or structural weaknesses.

A variety of different techniques and sensors are often required to obtain information, and bringing together the right expertise to perform an inspection above and below the waterline is not always a simple exercise. The second challenge is the location of the bridge site and the resulting environmental factors.

If the bridge crosses a fast-moving river or a river that is in a state of flood, this can cause additional difficulties. At a time when the bridge condition may need immediate attention, fast-flowing rivers and other environmental conditions can pose significant risks during bridge inspections. Ensuring the safety of personnel while collecting accurate data is a balancing act that requires advanced technology and meticulous planning.

Not only is there the safety aspect associated with getting close to a bridge in these conditions, but fast-flowing water in shallow environments can cause aeration in the water column that results in noise when using acoustic instruments.

Another issue is around the management of the resulting data collected. Large datasets generated during bridge surveys can be cumbersome to manage. Efficiently storing, accessing, and analysing this data is critical for making informed decisions about bridge maintenance and repairs. With so much at stake, it's crucial to have a reliable and streamlined process for surveying bridges. This is where advanced technology and data management tools come into play.

Combining Methods for Efficient and Accurate Surveying

At SEP Hydrographic, we typically acquire Multibeam Bathymetry of the riverbed and combine this with 3D Scanning Sonar data of the bridge abutments and other vertical structures. A high-frequency side scan sonar may also be used for debris surveys. This is then combined with terrestrial survey sensors, including LiDAR and photogrammetry, to provide a complete picture of the asset.

For bridges crossing fast-flowing rivers, we would ideally aim to perform a survey when the water is moving at its slowest.

Should the campaign seek to identify or monitor potential flood damage, there are sensor deployment options available that are of lower safety impact, for example, drone bridge inspections, crane deployment or Autonomous Surface Vessels (ASVs). It's key to establish horizontal and vertical control for the bridge site to combine all of these surveys together. This is particularly important when multiple survey methods are being used, as it ensures consistency and accuracy across all datasets.

Integrating all of this data into one cohesive dataset allows for efficient analysis and decision-making. This combined approach also reduces the risk of missing critical information or discrepancies between different surveys. It also ensures that all aspects of the bridge's structure are thoroughly examined, providing a comprehensive understanding of its condition.

Multibeam Bathymetry (MBES)

MBES is optimised for high-resolution mapping of the seafloor, emitting multiple sound beams to capture precise measurements.

3D Scanning Sonar

3D Scanning Sonar, such as the Blueview BV5000, is designed to produce high-resolution 3D imagery of underwater structures by generating dense point clouds.

LiDAR (Light Detection and Ranging)

Bridge inspection using LiDAR technology uses pulsed lasers to measure distances and create detailed point clouds.

Autonomous Surface Vehicles (ASVs)

Bridge surveys using ASVs are beneficial for areas that are particularly hazardous or difficult to access. These methods allow for safe and efficient data collection without putting surveyors at risk.

Drone Bridge Inspections

Bridge inspection using Unmanned Aerial Vehicles (UAVs) is helpful for hard-to-reach areas or when the river is in flood and captures aerial LiDAR and photogrammetry imagery to support visual inspection.

This data can then be used to create detailed inspection reports, 3D models and maps of the site and bridge structure.

Advancements in Bridge Survey Technology

Digital Twin Technology involves creating a virtual model of a bridge using real-time data from inspections. This digital twin helps monitor bridge construction and planning repairs, optimise bridge management over time, and provide a comprehensive view of the bridge's condition.

Artificial Intelligence (AI) and Machine Learning (ML) algorithms can analyse vast amounts of data, detecting potential issues before they escalate. Predictive analytics uses historical data to forecast future structural problems, allowing for proactive maintenance and extending the lifespan of bridges.

The integration of Internet of Things (IoT) sensors can continuously monitor factors like strain, temperature, and vibration, providing real-time data. This constant oversight ensures immediate detection of any anomalies, facilitating timely interventions.

Conclusion

As technology advances, we expect further developments in bridge survey and inspection service methods. With digital twin technology, AI and ML algorithms, and IoT sensors, bridge inspection and maintenance will become more efficient, cost-effective, and accurate. These advancements will also contribute to the overall structural integrity, safety and longevity of bridges, ensuring that they remain an essential part of our infrastructure for years to come.

Engineers and surveyors must stay up-to-date with these technological advancements to improve their processes and provide better structural solutions. So, while traditional methods like manual inspections will always be necessary, incorporating new technologies into bridge construction and surveys will undoubtedly lead to more effective results.

For more information about our bridge survey services, contact info@sephydrographic.com

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