Center for Transportation Studies, University of Minnesota
The goal of this project was to develop a series of steel pipe service-life maps for the state of Minnesota. The
California Method 643 is utilized to estimate steel pipe service life at locations throughout the state.
Over 560 soil resistivity and pH samples were collected statewide during summer 2014 along embankments of
state-trunk and county highways. Concurrent observations of soil texture, surrounding landscape, roadway type,
and water presence were also made; water pH and conductivity measures were made where applicable.
Data verification efforts to build confidence in field-measured soil pH and soil resistivity included comparing data
to other available datasets including geology, soil pH, electrical conductivity, and soil texture, as well as
observations available from district and county engineers. Field-measured soil pH data, with some exceptions in
Districts 2 and 6, generally aligned with the available STATSGO soil pH data, indicating that this layer could
reasonably be used in service-life calculations as it has greater resolution than provided by field data. In the
absence of a statewide soil resistivity or electrical conductivity map, field-classified soil textures and the statewide
STATSGO soil texture map were used to estimate soil resistivity values.
Calculations of service life using the above data were completed for 18-, 16-, 14-, 12-, 10- and 8-gage galvanized
and aluminized steel pipe across Minnesota. These maps were then compiled into a zone map and table that
presents the 90th percentile service- life estimate for various gages and types of steel pipe. Caveats and limitations
to this analysis are also discussed.
Heitkamp, Barbara; Marr, Jeffrey.
Minnesota Steel Culvert Pipe Service-Life Map.
Center for Transportation Studies, University of Minnesota.
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