Why Underwater Bridge Inspections Are Important

Bottom line: Underwater bridge inspections reveal scour, deterioration, foundation movement, and submerged hazards that topside inspections cannot see.

• For public works teams: NBIS inspection cycles, diver qualifications, Level I/II/III methods, and post-flood checks should all be part of bridge maintenance planning.
• For city leaders: These inspections support public safety and help communities plan repairs before underwater damage becomes visible from the road deck.
• What to watch: Timing matters; low-flow periods, debris, ice, vessel impacts, and endangered species can all shape inspection windows.
• F&V perspective: Fleis & VandenBrink uses engineer-divers and qualified bridge inspection leaders to document underwater conditions and repair priorities.

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Why Are Underwater Bridge Inspections Important?

Important structural components of bridges often lie beneath the water. Communities need to hire experts, like F&V, to determine if their bridges are structurally sound. Underwater bridge inspections are required by the National Bridge Inspection Standards (NBIS) every 60 months.

F&V divers inspect submerged bridge substructure units visually and physically. Divers look for foundation problems, any areas of deterioration, endangered species, and most importantly, bridge scour.

What Is Scouring?

Bridge scour is the primary cause of bridge failures in the United States. Scour is a natural developing process where flowing water detaches riverbed sediment from around bridge piers and abutments. It can lead to failure of important infrastructure and erode bridge foundations.

Expert Underwater Dive Services

F&V’s dive team members are professional engineers and National Highway Institute (NHI) Qualified Team Leaders (QTL). All F&V divers have advanced diver training as well as CPR, AED, first aid, confined space, and emergency oxygen administration certifications.

Underwater Dive Services

F&V’s dive team explores what you cannot see underneath the surface of the water. Our underwater dive services include:

• Underwater Level I Visual Inspections. F&V divers inspect submerged bridge substructure units visually. F&V divers look for structural integrity and any signs of bridge scour.
• Underwater Level II and III Detailed Physical Inspections: F&V divers complete a more detailed physical inspection of the underwater bridge structure by cleaning areas and making detailed measurements, such as sounding with a hammer to fully assess structural integrity. If defects are found, they are photographed with an underwater camera, and the findings will be recorded on an inspection form. Additional non-destructive or minimally destructive (NDE) can be performed upon warranted findings or at the request of the owner.
• Endangered Species Surveys: F&V dive team provides mussel surveys and mussel relocation services along rivers and bridges. For all projects, mussels are collected and inventoried by a biologist and relocated away from the area of impact.

How Often Are Bridges Inspected?

F&V recommends following the NBIS and inspecting topside bridges every 24 months and underwater bridge inspections every 60 months.

When Is the Best Time of Year for Underwater Bridge Inspections?

Underwater bridge substructures should be inspected every 60 months. They should also be inspected after floods, if there has been visible damage above water from a vessel impact, or a build-up of debris at piers or abutments. Ice floes can also damage substructures. F&V divers look at low-flow periods on waterways to pick the best time to dive when water currents will not affect their inspection.

Are Underwater Bridge Inspections Mandatory?

Underwater bridge inspections are required by the NBIS every 60 months. These standards were created in the 1970s and dictate how often they should be inspected and who is certified to complete an inspection.

Why Use F&V for Underwater Bridge Inspection?

F&V’s licensed engineer divers are passionate about protecting communities and municipal investments. With extensive training and certifications along with years of experience, they are the best at what they do. F&V’s dive team understands the importance of protecting your infrastructure and will make recommendations to bring design solutions for repairs and maintenance of these structures.

Mitigate Bridge Engineering Issues with Underwater Inspections

Conduct underwater bridge inspections before issues arise. Contact F&V’s certified underwater dive team today to schedule your bridge inspections, protecting not only your bridges but the commuters who travel on them.