Culverts function primarily as hydraulic conduits, providing the dual purpose of conveying water from one side of the roadway to the other, in addition to serving as traffic load-bearing structures. However, many culverts of today have experienced considerable wear and are in various states of disrepair. For this reason, proper culvert inspections are crucial to ensure functionality and structural integrity.

Culverts can often be thought of as “out of sight, out of mind” and, for this reason, can be overlooked when compared to larger bridge structures. However, the same critical issues that affect bridges are worth monitoring during culvert inspections and other non-bridge structure inspections.

This article discusses what to look for during culvert inspections and how culverts provide numerous benefits to the surrounding environment and infrastructure. Culvert inspections require an intimate knowledge of the materials used, design methodology, and field experience.


What is a Culvert Inspection?

A culvert inspection combines the knowledge of culvert installations, design criteria, individual skill and experience, and an understanding of culvert building materials. Culvert assessments are often a visual practice. Inspectors take notes and photograph defects to identify underlying problems. From there, further investigation can occur to determine the culvert’s condition.

Timber culvert inspections should occur every five years; for culverts constructed with other materials, an inspection should occur every seven years. More frequent inspections occur with higher-risk culverts, and inspections should meet the specific requirements of ongoing monitoring programs. Assessments should also increase in frequency for better safety and operation if there are obvious signs of deterioration.


Do Culverts Offer Environmental Benefits?

Culverts provide numerous solutions for human and aquatic ecosystems. They allow vehicles to pass over water-laden areas while allowing fish and wildlife to safely pass beneath surface traffic. A significant purpose of culvert installation is to better assist in stream flow, helping to effectively displace stormwater that might otherwise impact streets and buildings.

Another considerable benefit to culverts is their profound effect on the health of water channels, which fish and wildlife depend on. Unfortunately, poor culvert design or improperly maintained culverts can cause numerous downsides, such as erosion, scouring, and bank slumping. As a result, it can drastically impact the quality of the water and the surrounding habitats.


What Causes a Culvert to Fail?

Culvert failure can come from environmental conditions, usage, and age, while other common causes are pipe damage, clogs, failed or rusted inverts, washouts, joint separation, and more. Moreover, when culverts start to fail, they can impact the world around them.

The number one hazard that results from culvert failure is a sinkhole, which causes the roadway or railway to fail and become a danger to the traveling public. Sinkholes are created when the culvert structure is no longer displacing the water source properly and begins to undercut the roadway or traveling surface.

In addition to the property damage caused by sinkholes, they can cause accidents, increase traffic delays, interrupt transportation systems, and require hefty repair costs. There’s also the chance of debris and sediment from culvert failure having a negative environmental impact. Culvert debris can cause clogs in creeks and streams, directly impacting the migrant fish and their ecosystems. By practicing proper culvert inspections, there are fewer chances of culvert failure to occur.


Considerations for Culvert Inspections

So what is included in a culvert inspection checklist? There are various aspects of culvert inspections to ensure that the culvert maintains safety regulations and standard operations.

Some aspects of culvert inspections include culvert safety and assessment of its shape, size, and materials. Identifying the various factors of culvert inspection can ensure functional hydraulic performance and structural integrity.

Culvert Safety

A contributing factor to when culvert inspections should be conducted is the safe conditions it provides. Various hazards can occur during an inspection. Gaining access for inspection can result in fall hazards, as many culverts are often located in low embankments. Moreover, confined spaces are risky altogether. So, assessments typically occur during low-flow periods when culverts are easier to access.

Inspectors should avoid going in alone and always work together as a team. The team must follow state, local, and other safety regulations and practice common sense to avoid hazards and injuries. As such, inspectors must participate in culvert inspection training courses and programs to further prevent injuries and accidents.

Culvert Materials

Culverts are often made from many materials, including steel, plastic, corrugated metal, stone, and concrete. Depending on the materials used, each culvert type must meet specific design criteria, installation techniques, and hydraulic requirements. Culvert inspectors should familiarize themselves with the necessary measures for accurate inspections of the various material types.

When inspecting culvert material types, it’s crucial to look for buildup in the interior walls or inverts, clogging, and flow restrictions. Moreover, inspectors need to look for slope stability and joint integrity and closely monitor traffic surface conditions, end protection, and more. Lastly, finding cracks, shape changes, deflections, loss of metal, cracked bolt seams, and other foundational issues is vital.

Specific Inspection Assessment Items

There are various items to evaluate during a culvert assessment. The rate of corrosion and signs of abrasions, perforations, cracks, damaged joints, shape changes, and other physical changes are just a few of the items evaluated. Identifying the source of physical deterioration and condition changes can help resolve underlying issues and prevent further damage.


Inspection History, Baseline Measurements, & Inspection Frequency

When it comes to culvert inspection, it’s crucial to know its inspection history, frequency, and other measurements to monitor potential risks. In addition to regularly scheduled inspections, high flow and extreme storm events should prompt additional inspection measures. New developments can occur from high-risk weather conditions, such as channel alterations and increased runoffs.

If there are signs of considerable wear, deterioration, or warping, inspectors should increase their assessment frequency to prevent safety risks. Additionally, previous culvert history can help dictate the actions needed for improved culvert operation. Lastly, collecting accurate measurements can help serve as a benchmark for future inspections. Some measures include the angle of the culvert and road intersection, size of culverts, length of the culvert, debris buildup, roadway elevations, type of drainage area, and more.

When timber bridges start to show signs of wear and deterioration, or if slip-lining does not offer enough hydraulic capacity, installing a culvert bridge kit can offer a solution to improve hydraulic flow and load-bearing requirements. These solutions are designed to reduce railway and traffic downtime. At InfraSteel, our bridge culvert pipe solutions for timber or short-span bridge replacements are maintenance-free and can be quickly and easily positioned and covered in concrete.

Founded in 2003, Precision Pipe and Products Inc., DBA InfraSteel, is owned and operated by an experienced team. Our products focus on servicing customers by bringing value to business relationships through consistently high-quality structural steel solutions. If you have inquiries regarding our culverts and liners, contact our experienced team today for more information.

What To Look for During a Culvert Inspection