Estimating Service Life for Corrugated Steel Pipe Culverts

This research category paper is a work in progress that discusses the processes used to improve the service life estimation of steel culverts under roadways in the State of California. The service life of Corrugated Steel Pipe (CSP) culverts is largely dictated by the loss of wall section of pipe arising from corrosion. This corrosion is due to chemical and electrochemical processes based on two major factors: pH levels and the resistivity of the soil. Service life estimates are based on several additional factors: potential for culvert abrasion, changing soil moisture, temperature conditions, soil moisture content, presence of chloride in the soil, and proximity of lakes, wetlands, or marine environments. In addition to pH and resistivity, the CSUN Caltrans Research team has added culvert thickness loss, sulfate and chloride content, total dissolved solids (TDS), salinity, and land use. The thickness reader allows the CSUN Caltrans Research team to calculate the loss of metal from the CSP culverts' nominal thickness. The goal of this research is to improve the existing service life equations which is currently used by the California Department of Transportation and its associated test methods. To this end, modern non-destructive instrumentation is being implemented in the field to measure CSPs' thickness which is one of the key parameters under investigation throughout the State of California.