Comparing Resistivity and Conductivity in Metal Culverts
Currently, the New Mexico Department of Transportation (NMDOT) uses the “2018 NMDOT Culvert Resistance Spreadsheet” (CRS) when estimating the service life of culverts. The values of resistivity in the CRS for different types of culverts of varying material (steel, concrete, aluminum, plastic, etc.) and of varying wall thickness with different corrosive inhibitor coatings were collected from manufacturers’ specification literature. With all these manufacturers’ values being reported in resistance (ohm-cm), it was assumed that the electrical conductance (milliSiemens per meter, mS/m) values reported by the Natural Resources Conservation Services (NRCS) for soils throughout New Mexico were indirectly proportional to each other, based on Ohm’s law. Furthermore, the resistivity of the soil is determined in-situ adjacent to the culvert and the values reported by NRCS are from electrical conductivity (EC) tests conducted in a lab from field-collected soil samples. These two methods, in-situ and laboratory are significantly different in procedure and produce values of different units, ohm-cm (resistivity) and mS/m (conductivity), respectively. It is assumed that the laboratory test is more accurate than the field tests, which will be evaluated in this proposed project. Providing a better understanding of and evidence that these two methods, although different, produce results that are indirectly proportional to each other will enhance NMDOT’s continued usage of their CRS when calculating service life of culverts. OBJECTIVES: The main objectives of this proposal are as follows: Conduct a literature review of similar work on culvert service life estimation coupled with field and laboratory analysis. Research various (inexpensive and expensive) in-situ and laboratory soil testing equipment to be used for this study and then provide recommendations for NMDOT; Test various (inexpensive and expensive) in-situ and laboratory soil testing equipment on approximately 20 sites throughout New Mexico; Compare service life estimates to existing removed culverts with soil samples tested in-situ and in the laboratory and measure corrosive effects on these removed culverts; Validate the assumptions made in NMDOT CRS for culvert service life estimates; Adjust the CRS if needed.
Language
- English
Project
- Status: Completed
- Funding: $59,988.00
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Contract Numbers:
R924020
C06444
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Sponsor Organizations:
New Mexico Department of Transportation
1120 Cerrillos Road
P.O. Box 1149
Sante Fe, NM United States 87504-1149 Albuquerque, NM United States -
Project Managers:
Moya, Abigail
- Performing Organizations: Albuquerque, NM United States
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Principal Investigators:
Collison, Jacob
- Start Date: 20231204
- Expected Completion Date: 20251205
- Actual Completion Date: 20251205
Subject/Index Terms
- TRT Terms: Electrical conductivity; Electrical resistivity; Literature reviews; Metal culverts; Service life
- Geographic Terms: New Mexico
- Subject Areas: Bridges and other structures; Highways; Maintenance and Preservation;
Filing Info
- Accession Number: 01962503
- Record Type: Research project
- Source Agency: New Mexico Department of Transportation
- Contract Numbers: R924020, C06444
- Files: RIP, STATEDOT
- Created Date: Aug 5 2025 1:13PM