Assessing the Condition and Consequence of Failure of Pipes Crossing Major Transportation Corridors

There are uncased aging pipes crossing major interstate freeways and congested railroad corridors throughout the United States. In the case of the Portland water system, more than 100 uncased crossings have been identified. These pipes are what many consider “high consequence” pipes as they potentially pose greater financial impacts than those in the general pipe population, not only to the utilities that manage them, but to the public as well, as the effects of failure may be felt widespread throughout society. To capture the full effects of such an event, Triple Bottom Line (TBL) impacts to society are quantified in the risk management methodology. Understanding the failure modes and root causes of failure, condition, and consequences of failure of pipes crossing major transportation corridors will assist utilities in better managing these high consequence assets. The likelihood of failure can be refined by obtaining knowledge regarding the pipe’s operational and environment conditions, and historical performance. Estimating the financial consequences associated with main breaks has been facilitated by the development of transportation disruption models. By refining the likelihood and consequence of failure estimates, Portland Water Bureau (PWB) has been able to establish the business case for mitigation measures, including the potential for continued monitoring, additional valves, or pipe rehabilitation or replacement options.