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From page 48... ...
Although the final scope of this synthesis includes seismic susceptibility, slope and embank ment stability, watershed characteristics, and urban development and land uses as potential challenges of culvert resiliency, the interviewed case example state DOTs prioritize variability in extreme weather events as the focus of their resiliency efforts. It is worth noting that DOTs have guidance documents available for these additional challenges, but this section of the report documents DOT practices to enhance culvert resilience that align with state DOT prioritization of extreme weather events.
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From page 49... ...
Case Examples 49 Figure 32. Prioritization of large culverts for detailed adaptation assessments (Figure 3 of the District 7 Adaptation Priorities Report, Caltrans 2021)
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From page 50... ...
While there are not established service life extensions associated with individual repair and rehabilitation practices, the DOT does attempt to regain a 50-year service life from any work performed. Examples of practices to prolong service life and therefore enhance culvert resilience are the use of CIPP liners to provide an enhanced wear layer where abrasion is a problem and using different concrete mixes for invert paving to boost abrasion and corrosion resistance.
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From page 51... ...
4.1.4 Cost Assessment Methodologies for Culvert Resilience Improvements Caltrans has created an in-house computer software program called "AltPipe" that is used for selecting new culverts. The program analyzes characteristics unique to a location, such as soil PH
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From page 52... ...
CIMS only includes culverts and end treatments but has the potential to layer different maps to identify critical areas for risk management strategies; one such layer could include areas affected by climate change and extreme weather events. CIMS also includes informa tion for users such as how to conduct a culvert inspection, how to map culvert locations, and how to use the software to review the collected data.
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From page 53... ...
4.1.7 Practices to Address Embankment Overtopping All culverts are designed to handle a Q100 design storm (where Q is the quantity of the runoff; Caltrans 2020b) without causing objectionable backwater depths or outlet velocities.
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From page 54... ...
Figure 35. Caltrans' CIMS tool.
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From page 55... ...
Figure 36. CIMS homepage.
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From page 56... ...
Assets affected by the flood events have been overtopped and had their embankments eroded, which closed portions of Interstate 15 and Interstate 40 while the repairs were carried out. The DOT representatives suspect the non cohesive soils characteristic of desert locations are the reason behind the washouts.
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From page 57... ...
Long-standing requirements of the DOT are the specification of watertight joints and the requirement of higher joint performance for culverts in critical locations. 4.2.2 Maintenance Practices to Enhance Culvert Resilience FDOT uses liners and joint repair methods for remedial maintenance.
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From page 58... ...
Figure 37. Screenshot of FDOT's Sea Level Scenario Sketch Planning Tool (Florida Department of Transportation Office of Research, Development, and Technology 2012)
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From page 59... ...
Figure 38. Screenshot of FDOT's Culvert Service Life Estimator (FDOT 2022b)
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From page 60... ...
4.2.4 Cost Assessment Methodologies for Culvert Resilience Improvements Resiliency improvements are decided upon by districts based on previous experience with lining technologies. District maintenance offices typically select and specify products known to be successful for the type of damage experienced and previous repair successes.
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From page 61... ...
Although there is no active research in this area, FDOT emphasizes the need for understanding criteria that were in effect when systems were built. 4.2.7 Practices to Address Embankment Overtopping While overtopping is not a significant issue for FDOT, it has experienced overtopping related to excess water during a hurricane storm surge.
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From page 62... ...
FDOT is compiling a list of specifications for various installations and case examples of their performance after severe weather events, with the goal of providing state engineers with a toolbox to aid in resilient design. 4.2.9 Post-Event Response Practices The two main post-event response practices employed by FDOT are the inspection and desilt ing of culverts after every storm event.
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From page 63... ...
." (MDOT 2024b) as well as incorporating extreme weather event risk assessment into decision-making to accommodate and mitigate potential challenges due to climate change.
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From page 64... ...
4.3.4 Cost Assessment Methodologies for Culvert Resilience Improvements MDOT has step-by-step guidance for culvert condition rating detailed in the Highway Drain age Manual to identify and compare appropriate and cost-effective improvement strategies (MDOT 2023a)
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From page 65... ...
The Highway Drainage Manual specifies flood-level allowance for different roadway classifications; additional considerations include FEMA-mapped floodplains and the Maryland Department of the Environment dam safety guidelines for roadway embankments. For designs that do not meet the required metrics, to allow justification, a design exemption must be obtained that evaluates the risk.
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From page 66... ...
Figure 44. Sea-level rise map of Maryland's coastal region, provided by MDOT.
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From page 67... ...
MnDOT stresses the need for infrastructure risk reduction through assessments, check storms (checking against design storms) , and extreme weather event projections to prioritize assets for resilience.
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From page 68... ...
Figure 46 shows an example of a TAMS HydInfra culvert inventory window. The TAMS HydInfra database includes policies and manuals for inspection training for iden tifying common failure mechanisms for the different culvert materials; it has been successfully producing consistent culvert condition ratings statewide.
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From page 69... ...
Figure 46. MnDOT TAMS HydInfra inventory window (MnDOT 2021)
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From page 70... ...
MnDOT representatives commented that culvert condi tion should be prioritized when evaluating culvert vulnerability and risk of overtopping; they also emphasized the importance of considering culvert condition when determining funding. 4.4.4 Cost Assessment Methodologies for Culvert Resilience Improvements When scoping projects, MnDOT compares various resilience improvement methods.
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From page 71... ...
This tool will identify culverts at risk to extreme weather events and prioritize maintenance of these assets. The DOT is working to establish strong datasets for each of the information avenues, but the current prototype shows strong potential to reach full maturity within a few years.
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From page 72... ...
Figure 48. MnDOT Risk Corridor tool screenshot (courtesy of MnDOT)
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From page 73... ...
The representatives commented on internal debates about watertight versus soil-tight joints; the DOT is encouraging use of gasketed culvert pipes but is not yet specifying watertight joints. 4.4.7 Practices to Address Embankment Overtopping MnDOT is collecting information on overtopping locations and has found the results to be dependent on district topography.
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From page 74... ...
Virtual vulnerability assessments can then be applied to other loca tions that have not experienced extreme events. Combining the real-world and virtual vulner ability assessments creates a prioritization plan of the less resilient assets and those damaged during extreme weather events.
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From page 75... ...
Current Late Century, RCP 8.5 Figure 50. Flood exposure risk in Dodge County, Minnesota (courtesy of MnDOT)
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From page 76... ...
This will allow for new design standards to protect assets at risk to the effects of climate change and inform economic decisions. Figure 51 details the potential impact of extreme weather events on Ohio's transportation network.
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From page 77... ...
Case Examples 77 Figure 52. ODOT's GA scale (ODOT 2024a)
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From page 78... ...
4.5.2 Maintenance Practices to Enhance Culvert Resilience ODOT uses different techniques for culvert rehabilitation to extend service life without full replacement. A cost-effective and frequently used practice for extending service life of specifically corrugated metal culverts is concrete invert paving.
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From page 79... ...
4.5.4 Cost Assessment Methodologies for Culvert Resilience Improvements ODOT does not follow a life-cycle cost or cost–benefit analysis framework but does factor an expected design service life of 75 years into cost decisions. The DOT uses a durability design methodology when installing new culverts; in a recent durability study conducted in partnership with Ohio University, researchers reviewed in-service culverts, evaluating the material condition and service life to create a prediction methodology using regression equations.
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From page 80... ...
Figure 53. Durability design example from ODOT's durability design spreadsheet.
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From page 81... ...
ODOT uses the word "conduit" as a term for culvert pipe. More restrictive construction installation and post-installation inspection requirements are under development; these are based on culvert location and other risk factors such as facility type, fill height restricting the ability to perform open-cut replacement of culvert pipe sections, locations with existing flooding or inundation problems, and risk due to culvert size, condition, and ability to be thoroughly inspected.
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From page 82... ...
The representatives noted that industry has pivoted toward the use of aggregate as the preferred backfill material, although the increasing use of #57 during installation, regard less of culvert material, has led to complications that will be addressed in future projects. Sand has been an acceptable choice for backfill material because of its compaction potential, especially when compared to #57 and its lack of gradation, but the use of sand with metal culvert pipes is a primary concern because of the risk of infiltration from perforation and invert abrasion.
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From page 83... ...
The DOT is considering identification of frequently affected locations in its inspection program to mitigate roadway shutdowns and damage to assets from extreme events. 4.5.10 Future Potential Research ODOT representatives noted that ODOT's biggest challenge is the lack of formalized rehabilitation practices, specifically when it comes to spray-applied liners.
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