Culverts. Approximately 196,000 of them underlie Michigan’s local roads alone. Road users drive over them and, many times, barely notice culverts are there. According to 2018 data, the replacement value of culverts owned by Michigan’s local road-owning agencies is $1.48 billion.1 At the same time, 33 percent of those culverts are in poor or severe condition.
The high value of Michigan’s culvert assets commands that attention be given to the aging and deteriorating nature of its culvert infrastructure. As such, inventory and condition data is increasingly important for managing and maintaining culvert assets. By using their culvert inventory and condition data, Michigan local road-owning agencies can apply asset management principles to their culvert infrastructure, using optimal fixes tailored to each culvert’s design and construction at a time when those fixes will be most cost effective.
Why Gather Culvert Data
Inventory and condition data for transportation assets like roads, bridges, culverts, and traffic signals form the foundation for good asset management practice. According to Public Act (PA) 325 of 2018, asset management is “an ongoing process of maintaining, preserving, upgrading, and operating physical assets cost effectively, based on a continuous physical inventory and condition assessment and investment to achieve established performance goals”. Local road-owning agencies collect and store asset inventory and condition data in in-house-developed files or databases or in software like Roadsoft. Agencies like Kent County Road Commission (CRC) and Washtenaw CRC have been using this culvert data to track their culvert assets and make data-driven decisions on maintaining these assets.
Later this year, the Michigan Transportation Asset Management Council (TAMC) will be releasing a culvert guidebook to help local road-owning agencies in developing their culvert data collection program. The manual will include a rationale, guidance on how to collect culvert inventory and condition data, and references for where to find further information on equipment and safety for culvert data collection efforts.
Culverts, Bridges, and Storm Sewers: What’s the Difference?
Culverts can be defined as linear drainage conduits underneath a public roadway (not under a driveway), a definition that was used for the Michigan TAMC’s culvert pilot report in 2018.1 The differentiating factor between culverts and bridges is span length: while the Federal Highway Administration considers “bridges” as those structures having a combined span (if consisting of several openings) of equal to or greater than twenty feet and thus eligible for inclusion in the National Bridge Inventory, culverts have a combined span of less than twenty feet. Unlike storm sewers, culverts are open at both ends and do not include intermediate drainage structures (e.g., manholes, catch basins).
Gathering Data Safely
To gather culvert data requires local-roadowning-agency team members to visit each culvert site, assess the culvert’s inventory features, and inspect its condition. Collecting inventory and condition data may involve inspecting areas that have difficult access, confining spaces, dark areas, and high water.
Local road-owning agencies—like Kent CRC and Washtenaw CRC—are responsible for setting policies and procedures for staff involved in culvert data collection efforts. So, how do local road-owning agencies collect culvert data safely?
Agencies can draw on resources related to bridge and culvert inspection that are available from state and federal agencies to their culvert data collection practices. For example, the American Association of State Highway Transportation Officials’ (AASHTO) Culvert & Storm Drain System Inspection Guide Chapter 3 outlines inspection procedures and provides safety guidance. The Michigan Department of Transportation’s Michigan Structure Inspection Manual (MiSIM) Chapter 13 covers bridge inspection safety issues that may be applicable to culverts.4 And, the Occupational Health and Safety Administration (OSHA) has guidelines for inspecting confined spaces5, areas with high water, and areas near utility lines.
To these resources, local road-owning agencies add their own field experience to determine when and how to apply safety guidance from state and federal agencies to each of their culverts’ unique circumstances.
Local Road-owning Agencies Share Tips for Safe Culvert Data Collection Mike TenBrock, project engineer for Kent CRC, begins by assessing culverts as belonging to one of three groups: “ones you can enter by wading,...ones you can enter by a small boat,...and ones you can’t get into and have to look down the barrel”.
Sometimes, seasonal or weather-related increases in water levels temporarily prevent inspecting culverts. However, TenBrock said some culverts are always inaccessible: “We don’t want our people going into those culverts. It’s not worth it,...the benefit is so trivial compared to the risk.”
For those culverts, he says Kent CRC relies on other cues to determine culvert condition. “Sometimes you see a little distress [on the roadway]—a classic transverse crack where the culvert lies, that’s a key you are getting movement with the culvert.” Determining whether a culvert is accessible for safe inspection is the first step in a culvert data collection program’s safety efforts.
When formal guidance on culvert data collection practices is absent, TenBrock bases all his culvert data collection decision making on the “Grace Rule”. He explained, “My main rule of thumb in anything we do is: I wouldn’t ask any of my people to do what I wouldn’t ask my own kids to do for me.” Referencing his daughter Grace, TenBrock continued, “It boils down to what we will call the ‘Grace Rule’; that’s the litmus test we use.”
Working Where Spaces Seem Confining
Sometimes culverts can have low clearances between water inside of it and the crown of the culvert or can have relatively narrow widths. In addition, perspective and interior darkness can make both the opening at the opposite end of the culvert and the culvert itself seem smaller than it actually is.
Aaron Berkholz, senior project manager for Washtenaw CRC’s Design and Construction section, explained, “A culvert is open at both ends, so they aren’t necessarily defined as a confined space; but, there’s a certain aspect of it that’s confining...there’s only the entry and exit at one end or the other.”
Berkholz says the Washtenaw CRC interior inspection process is done near the ends of the culvert. “It’s not been our practice to walk the entire length of the culvert,” he shared.
For Berkholz, deciding how to collect culvert data safely is a matter of being conscious of the condition and the risk and having the appropriate field experience. The data collection team members should assess a culvert before entering it (see Questions to Ask Yourself, next page, for consideration when determining safe entrance into a culvert).
To that, TenBrock added, “We advise our people, if it looks like you can’t easily be retrieved or tended to if you encounter distress in the culvert, then you shouldn’t go in there.”
Working around Water
Accessing areas around and in the culvert during data collection sometimes necessitates wading through the stream that passes through the culvert. “When you wade into a stream, you have to be thoughtful about the velocity and the depth of the water,” reflected Berkholz. “It’s amazing, the force of the water.”
To guide their culvert data collection practices when working around and in the associated stream, both Berkholz and TenBrock call upon wisdom gained through their fishing experience.
TenBrock shared, “I learned this from trout fishing: if [you multiply] the speed of the water and the depth...and the product of that equation is anything that approaches nine, you’re going to be swept up off your feet and end up downstream.” What TenBrock references is known as the “3x3 rule”, a rule based on water that has a depth of 3 feet and is flowing at a velocity of 3 feet per second; when the product of the depth and velocity exceed 9 feet squared (or 0.8 meters squared) per second, a person entering the water is at risk of being swept away. So, even as little as 1 foot of water can be treacherous if its velocity exceeds 9 feet per second.
Hui, an engineer on Berkholz’ team at Washtenaw CRC, is experienced in culvert data collection. “I’ve had instances where I wore my waders and the water came up to my hips and then, all of a sudden, [I stepped into] a hole and the water went past my waders,” he shared.
“Having a survey rod [—something that is relatively indestructible—] helps a lot,” recommended Hui. “You can poke and pry and see if the ground is soft before you go into it and can also measure how deep [any water or mud are].”
Berkholz, who has encountered holes himself while fishing, added that it’s important to be “thoughtful about the depth of the water you are considering wading into” when collecting culvert data.
In early spring and late fall, temperatures of water passing through culverts can hover around the freezing mark, making hypothermia a potential hazard. Therefore, TenBrock recommends having a warm truck nearby when collecting culvert data and a change of clothes.
Because of the risks involved when working around water or in confining spaces, both Kent CRC and Washtenaw CRC employ a buddy system. “We travel in pairs typically,” explained TenBrock. Berkholz added, “We definitely want to employ the buddy system where we need to so we promote our safety.”
When the agencies do send out personnel to collect culvert data on solo data collection efforts, they make sure the risks are lower. “If you send people out alone, their threshold for risk should be reduced considerably in terms of entering culverts, walking, wading, that sort of thing,” explained TenBrock.
Hui has performed numerous solo culvert data collection efforts. “I always let someone else know I am out [looking at] culverts, [I put it] on my schedule in the calendar [with the] culverts I’m looking at and their locations [and] lengths,” he said. “So, there’s no question I’m out there and there’s no question where I would be if someone needed to look for me.”
Hui emphasizes the importance of having the right personal protective equipment (PPE) and tools—safety vest, work boots, waders, and a survey rod—for these data collection efforts, but more importantly, he takes with him common sense: “I think a lot of it is common sense—if [the stream] is going fast, if it is a strong current, don’t go into it.”
Of Snakes and Ticks and Poisonous Plants
Culvert data collection requires data collection team members to work in and around potentially sharp objects, sloped surfaces with soft soils, a variety of vegetation and insects and animals, and road or highway traffic. Team members also chance working in adverse weather conditions as they work outdoors.
When it comes to collecting data on culverts that potentially have sharp edges, Hui said, “We always have our gloves, we always have something that can prevent us from touching the culvert directly.”
Hui is also careful in approaching the culvert. “ I think over time you develop an understanding of how soft or slippery a soil can be, how steep that embankment is leading up to the culvert,” he shared. “We are taught to step sideways as we are going down [hills or the embankment], [so] you can have as much surface area under your foot as possible as you are trying to [go] down something steep, and [to use a] survey rod, some kind of support you can have in your hand.” He has learned this with time and experience collecting culvert data.
That survey rod also comes in handy in snake country, according to TenBrock. “It’s a good idea to walk with a rod...and poke your way through any grass areas you can’t see...and walk with a heavy foot,” he advised. “Rattlesnakes are so camouflaged, you won’t see the snake, but typically they will slither away.” TenBrock shared that others at Kent CRC have encountered Massasauga rattlesnakes in their field work.
Equally as dangerous are ticks with their potential to spread Lyme disease. “At this time of year, we’re starting to get into tick season, so insects are another thing we look out for,” explained Nate Murphy, an engineer on Berkholz’ team at Washtenaw CRC. “Tuck your pants in your socks and do a check afterwards. Ticks are not something to take lightly.”
Berkholz says Washtenaw CRC uses a video during employee orientation to educate employees on safe practices when it comes to ticks. The agency also provides employees with additional information as necessary as well as tick repellents.
“Should you find a tick on yourself,” said Berkholz, “we have guidance on how to remove it and on things like saving the tick in case you do develop a rash or symptoms.”
In addition to educating employees on ticks, Washtenaw CRC’s orientation includes information on identifying poison ivy and poison oak and what to do if an employee comes into contact with one of these plants.
Safety Begins at the Road
Berkholz, Hui, and Murphy highlight the importance of roadside safety when collecting culvert data. They note their work near the shoulder for culvert data collection is typically brief enough that it doesn’t require a lane closure. The Federal Highway Administration’s Manual of Uniform Traffic Control Devices Part 6 and the Michigan Department of Transportation’s Michigan Manual of Uniform Traffic Control Devices Part 6 outline principles and procedures for working on or outside of the shoulder of the road.
Berkholz believes that distracted driving is a big concern when working near live traffic. “There’s a world of distractions, of someone just not being mindful of their driving habit,” he said. “Keep your head on a swivel and be aware of the traffic being present... [and have drivers] know that you are there.”
“Keeping alert,” concurred Murphy, “I think that’s a very important part of being safe in the field.”
Getting Started
“If there’s a [road-owning agency] that hasn’t started looking at their culverts as a safety factor for the motoring public, I think it’s incredibly important that they start this process of identifying ...[their culvert] assets,” urged Murphy. “Then, [they should] develop that safety protocol that is necessary for anyone who goes out in the field.”
Berkholz, Hui, and Murphy call out one-on-one training—or shadowing an experienced person who has collected culvert data—as most helpful for learning how to collect culvert inventory and condition data safely.
They say agency training and resources are also helpful. Agencies can follow the Michigan TAMC website (michigan.gov/ tamc) and the Center for Technology & Training website (ctt.mtu.edu/asset-management-resources and ctt.mtu.edu/training) for resources and training related to culvert inspection, culvert condition assessment and asset management as they become available.
In the end, though, TenBrock advises others to “use common sense, use an abundance of caution”. He says that even though culvert data collection is not “high-stakes danger”, problems still arise. “A little bit of caution goes a long way.”
RESOURCES
- Bershing, Scott; Colling, Tim; Gilbertson, Chris. 2018 Michigan Local Agency Culvert Inventory Pilot Evaluation Report. Michigan Transportation Asset Management Council, 2018. Available: http://ctt.mtu. edu/asset-management-resources and https://www.michigan.gov/tamc/0,7308,7-356-82159---,00.html.
- Act No. 325, Public Acts of 2018, State of Michigan. Available: https://www.michigan.gov/documents/ tamc/2018-PA-0325_636185_7.pdf
- American Association of State Highway Transportation Officials. Culvert & Storm Drain System Inspection Guide. 2020. Available: https://store.transportation.org/Item/CollectionDetail?ID=213.
- MichiganDepartmentofTransportation.MichiganStructureInspectionManual(MiSIM).2017.Available: https://tinyurl.com/mdot-misim
- Occupational Safety and Health Administration. Confined Spaces. United States Department of Labor. Available: https://www.osha.gov/confined-spaces.
- Occupational Safety and Health Administration. Standard 1926.106 Working over or near water. United States Department of Labor. Available: https://www.osha.gov/laws-regs/regulations/ standardnumber/1926/1926.106.
- Occupational Safety and Health Administration. Standard 1926.1408 Power line safety (up to 350 kV)--equipment operations. United States Department of Labor. Available: https://www.osha.gov/ laws-regs/regulations/standardnumber/1926/1926.1408.
- Urban Flooding (blog). Flood Safety Guidelines for Depth and Velocity, 2013. Available: https://tinyurl. com/overlandflood-guidelines.
- Federal Highway Administration. Manual of Uniform Traffic Control Devices. U.S. Department of Transportation. 2012. Available: https://mutcd.fhwa.dot.gov/.
- Michigan Department of Transportation. Michigan Manual of Uniform Traffic Control Devices. 2011 and 2019. Available: https://tinyurl.com/mdot-mmutcd.
- Adapted from: Culvert Risk Assessment Guideline. Roads and Traffic Authority of New South Wales, 2008. pp 12-13. Available: https://tinyurl.com/ipwea-culvertguideline.
- Noll, Jim and Frascella, Bob. Practical Factors and Considerations Related to Culvert Inspection. Contech Engineered Solutions. 2021. Available: https://tinyurl.com/conteches-culvertinspection.
More details at: http://michiganltap.org/sites/ltap/files/publications/bridge/bridge33-4.pdf