Navigating the Deep: Why Underwater ROV Inspection is Ideal for Long-Distance Tunnels

The team at UCC typically defines a tunnel as “long-distance” based on a combination of factors that impact diver safety and inspection efficiency. While the exact distance can vary depending on project specifics and technological advancements, a general threshold lies between 500 and 1,000 feet.

Tunnels meeting or exceeding this threshold of 500-1,000 feet are classified as long-distance for a crucial reason: diver limitations. Traditional penetration diving methods become increasingly challenging beyond these distances. Decompression requirements become stricter, limiting how far a diver can travel underwater and the amount of time they can spend effectively inspecting the tunnel. Long dives in confined spaces also pose increased safety risks.

The logistical complexities of inspecting long tunnels with divers add another layer of challenge. Ensuring diver safety necessitates additional manpower and equipment to support penetration diving and decompression needs. This translates to a more elaborate and time-consuming operation compared to inspections using alternative methods.

Unlike divers who primarily focus on the tunnel’s overall structure, ROVs excel at identifying specific internal components, assessing joint integrity, and detecting debris or damage:

• Internal Infrastructure: Equipped with high-resolution cameras, ROVs navigate confined spaces to inspect critical elements within the tunnel, such as chemical feed lines, solution lines, and expansion clamps.
• Joint Integrity: Their ability to maneuver close to the tunnel walls allows for a thorough inspection of joints, identifying separations or abnormalities that might require further attention.
• Debris & Damage Assessment: ROVs equipped with sonar technology can effectively scan the tunnel floor, identifying debris accumulation for targeted clean-up efforts and signs of spalling and other concrete abnormalities, providing valuable information for structural assessments.

ROV inspections go beyond a simple visual sweep. They offer a comprehensive evaluation of the tunnel’s condition, and their detailed data allows for a proactive approach to tunnel maintenance to ensure the long-term safety and functionality of these vital underwater structures.

Underwater ROV inspections often provide advantages over divers in long-distance tunnels, as these advanced robotic vehicles are tethered to a surface control station and equipped with high-definition cameras, sonar and other sensors. During long-distance inspections, ROVs help to:

• Improve Safety: Underwater ROV inspection minimizes diver exposure to potential hazards in long tunnels, prioritizing safety throughout the process.
• Extend Range: ROVs are not restricted by decompression needs, allowing them to travel near unlimited depths and vast distances within tunnels, typically completing inspections in a shorter timeframe.
• Enhance Efficiency: ROVs can navigate long distances quickly and efficiently, covering more ground and providing a broader initial assessment of the tunnel’s condition.
• Reduce Crew Size: ROV inspections typically require a smaller on-site crew compared to traditional diving operations.
• Gather Data in Low Visibility: ROVs equipped with advanced sensors, like cross-sectional sonars, can gather valuable data like debris accumulation measurements even in low-visibility conditions, something that can be difficult or even impossible for divers.

Watch our divers and ROVs at work and learn more about our ROV inspection services, including the use of the Deep Trekker Pivot.

At UCC, we don’t view ROVs as a replacement for divers, but rather as a powerful tool that complements our team’s expertise. This collaborative approach not only enhances the efficiency of long-distance tunnel inspections but can also deliver significant cost savings, reduced downtime and improved safety for your operations.

In most scenarios, ROVs perform a general condition assessment of the tunnel. Their maneuverability and ability to travel long distances quickly allow them to gather crucial data and create a clear picture of the underwater environment. This initial assessment, consisting of high-resolution video footage, sonar readings, and various measurements, helps identify areas that may require detailed attention from our divers. This data becomes a vital foundation for further analysis and decision-making when it comes to planning a diver’s underwater tasks, and by pinpointing specific areas of concern, we can reduce the time and resources for inspections, ultimately reducing costs.

ROVs provide invaluable support in scenarios where traditional diving methods face challenges. Their compact size allows them to navigate small tunnel diameters that might restrict divers’ movements. While UCC divers are trained to handle minimal water flow within the tunnel, ROVs can operate efficiently in environments where water velocity is difficult to control. This synergy ensures that both divers and ROVs are used where they perform best, enhancing overall safety and improving the inspection process.

Downtime can also be significantly reduced, in some situations by 2X, when underwater ROV inspection is employed. The ability to complete initial assessments quickly allows for a more efficient allocation of resources. Divers can then focus on targeted inspections in specific areas identified by the ROV, minimizing the overall inspection time and potentially reducing the amount of time a tunnel needs to be shut down. Faster inspections mean your operations can resume sooner, boosting productivity and minimizing costly interruptions.

By strategically combining ROV technology with our divers’ expertise, UCC helps to ensure a safe, efficient, and comprehensive approach to long-distance tunnel inspections. Our collaborative methods not only enhance the quality of inspections but also provide you with actionable insights to maintain and improve your infrastructure. Learn more about our commercial underwater construction and inspection services and contact our team to discuss your unique needs.