The probability of a spill occurring along a pipeline lies at the core of risk management for pipeline operators. Thus, a look at historical accident trends may provide some insight into this probability. Analyses of data for US petroleum product pipelines operating between 1982 and 1991 indicate that such pipelines of short-to-moderate lengths (for example, 50 miles) are likely to have at least one reportable spill within a 20-year period. Longer lines (as much as 1,000 miles, for example) may suffer a reportable spill within 1 year. These are major conclusions of analyses by EFA Technologies Inc., Sacramento, of statistics compiled by the US Department of Transportation (DOT) on liquid pipelines operated under the Code of Federal Regulations (CFR) Title 49D, Part 195 Transportation of Hazardous Liquids by Pipeline.