It has been over a decade and a half since The Pipeline Safety Improvement Act of 2002 was passed into law mandating the creation of the Integrity Management (IM) Rule. Since then, an estimated hundreds of millions of man-hours and tens of billions of dollars spent by operators, consultants and contractors in support of this effort, it is a worthwhile effort to look back and see if there has been a measurable improvement in safety. In 2003 when the final rule was published, the Research and Special Programs Administration (RSPA) estimated the cost to be $11 billion over 20 years that would partially be offset by $6.2 billion in benefit savings due to reduced consequences and averting even larger accidents than have been seen historically.1 While it is impossible to prove what didn't happen because of things that were found and repaired as a result of operators' IM programs, the expectation is that measurable safety improvements would reflect in the incident statistics published by PHMSA2. As part of the IM Rule, the Government Accountability Office (GAO) was directed to assess the effects on public safety from the IM program for gas transmission pipelines. In 2006, the GAO concluded, "As the program matures, PHMSA's performance measures should allow the agency to quantitatively demonstrate the program's impact on the safety of pipelines."3 While the GAO report looked at some of the broad trends early in the program it was too early to draw any conclusions if the public was safer. There have been other studies that have examined the broader trends, but they have never taken the step of applying statistical tests to see if the variation is outside what would be expected due to random fluctuations. But now with the benefit of time, especially since operators have finished their baseline assessments and most pipelines are into reassessments and potentially second reassessments, there is a significant amount of data in the public domain to attempt to assess the effects of IM. To test if a measurable difference in safety has been made, a rigorous statistical methodology will be employed to determine if there has been a significant shift in incident rates and severity of incidents since implementation of the IM rule. The analysis will examine the metrics of fatalities, injuries, incident count, and property damage for the years prior to (1986 - 2003) and following (2004 - 2018) implementation of the IM rule. While the incident data includes both High Consequence Area (HCA) and non-HCA pipelines, the IM performance measures reported to PHMSA is the number of leaks, failures and incidents that occurred specifically in HCAs. Although the IM Rule was published in December of 2003 and the HCA Rule prior to that in 2002, for the purposes of this study, 2004 will be considered the first year under the IM Rule.
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