Optimising the efficiency of bridge surveys

Posted 6 November 2020

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. 

Skerne Bridge, Darlington, Image Credit: Network Rail
Skerne Bridge, Darlington, Image Credit: Network Rail
Combined survey dataset
Combined survey dataset
Richmond, North Yorkshire
Richmond, North Yorkshire
Bridge survey data example
Bridge survey data example

Why can it be a challenge to survey bridges?

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.  When it comes to performing a survey, or remedial work, this means that different techniques or sensors are required. 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 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. Not only is there the safety aspect associated with getting close to a bridge in these conditions, but 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 itself. For a busy asset management professional, it is essential that the information is easy to access, allows conclusions to be drawn, which can inform any follow on actions or remedial work. 

How can they be surveyed efficiently?

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. For debris surveys, a high-frequency side scan sonar may also be used. 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. Suppose the campaign seeks to identify or monitor potential flood damage. In that case, there are sensor deployment options available that are of lower safety impact, for example, crane deployment or Autonomous Surface Vessels (ASVs).

To present the resulting information in the best way, we've invested in an online data portal. Bringing together various datasets, the web-based system allows access to bridge survey data in a way that is simple to use and shared easily with relevant stakeholders. 

For more information about our bridge asset inspection services contact info@sephydrographic.com

Related Pages: Pulsar Static Acquisition Asset Inspection Survey Hydrographic and Geophysical Survey