Drone inspection for bridges – a technology for transformation?

With the advent of drones, bridge inspections may soon be taking a whole new direction.

IPC at a glance

  • A nondestructive testing (NDT) services company that applies proprietary and patent pending NDT inspection technology to assess the structural integrity of critical bridges and infrastructure.
  • It utilizes patented robotic equipment to conduct condition assessments, providing quantitative data to the department of transportation.
  • It has formed a strategic alliance with DSI Construction where the latter will utilize the proprietary technology developed by IPC for the nondestructive inspection of post-tensioning cables and stay cable systems.

When it comes to bridge inspection, the safety of the inspector and public as well as the effectiveness of the technology must be considered. Till now most bridge inspections have been manual in nature providing subjective results that make it difficult for the bridge owner to budget maintenance and repairs.

When you hear talk about what the next big thing in bridge inspection might be, the conversation quickly turns to drones. Discussions about the effectiveness of this technology along with the safety and cost saving it offers are ongoing.

Drone inspection for bridges are being tested by some bridge owners around the US in place of traditional methods. One would think that it cuts down the risk and cost involved while providing a useful technology that would be more effective than earlier methods.

Drone Inspection Credit: Infrastructure Preservation Corp.
Why drones?

Traditional methods of bridge inspection include manual inspection with the help of inspection vehicles, rope access or use of ladders as well as aerial work platforms – depending upon the kind of bridge, evaluation and the inspection area of the bridge.

Regardless of which part of the bridge has to be assessed or which method used for the inspection, the associated cost and hazard remain a big challenge. Ropes or ladders are dangerous to human life. Aerial work platforms used for aerial inspections are costly and require a high-level of training as well as expertise to ensure safe usage.

Also, inspection of a bridge poses unique challenges which make it crucial to identify the right tool for the job in order to enhance the effectiveness of the process while cutting cost and time. This best thing about drone technology is that it serves many of these purposes. In the past few years, drones have undergone significant evolution and are becoming commercially viable.

Engineering companies are reluctant to adopt new technology as it takes away their traditional man hours and billing time but as the infrastructure gets worse, a new way forward has to emerge. The use of drone inspections for bridges may be one of these.

Do they work?

There are many studies being conducted in various states about the viability of drones in infrastructure inspections. I see many states spending so much money on the same studies over and over again. Let me give you a summary of our experience with drones.

At IPC, we first worked on drones to inspect high mast light poles. Traffic would slow and swerve which gave us pause. The inspection itself was not precise enough to use for high mast light pole inspections as well was very time consuming as multiple runs were needed to achieve 100% coverage.

Our team opted to develop a robotic crawler instead which solved our mission of conducting an inspection that provided more quantitative data, was safer, faster and could be conducted at a lower cost. We used the same principals as well as the FHWA and AASHTO guidelines to develop a high mast light pole inspection and repair robot. You can see both here. After the high mast light pole tests we moved to bridge inspections. Drone inspections are ideal as part of the inspectors toolkit to examine hard to reach areas from the water line to the bridge deck.

In early testing many drones themselves had flaws that had to be overcome. I know in our early tests of drones for infrastructure inspections the 12-15min. flight time was too little to be of any use for infrastructure so we developed a drone that could stay aloft for 55 minutes. That solved one issue. After a few initial tests in the field we realized that flying drones above traffic would not work. It was distracting to drivers and could cause accidents on the road, so inspections over roadways had to be scrapped.

Robotic Inspection Credit: Infrastructure Preservation Corp.

Where drone inspections did shine was between the water and the slab where the public could not see the drone in flight, on railroad bridges and tons of other infrastructure that was away from traffic or in harms way. Some of the natural uses for drone inspections were oil pipelines, construction site inspections, windmills, smokestacks and dozens of other structures where a visual inspection was needed in a hard to reach place or large area.

As technology advanced we could conduct crack inspections, locate leaks in pipelines and check any hard to reach area on a large bridge and report back many issues that were almost impossible to detect before. While drone inspections may not transform the industry the use of a cool technology like drones may prompt bridge owners to start looking at other existing technologies to help advance the way inspections are conducted.

In addition, as drone technology does continue to improve, there will be dozens of other uses for drone inspections. For now as far as bridge inspections, I would keep drones as just 1 tool in the inspectors toolbox and keep them flying below traffic. If you would like to discuss a specific drone project, please click here.

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