The intent of this paper is to investigate installed cost overruns of pipeline-compressor-station projects. A total of 220 pipelinecompressor-station projects constructed between 1992 and 2008 have been collected, including material, labor, and miscellaneous, land, and total installed costs; and compressor-station capacity; location; and year of completion. Statistical methods are applied to identify the distribution of cost overruns and overrun causes. Overall average overruns of pipeline-compressor-station material, labor, miscellaneous, land, and total costs are 3, 60, 2, -14, and 11%, respectively. Cost estimations of compressor-station-construction components are biased except for the material cost. In addition, the cost-estimation errors of underestimated compressorstation-construction components are generally larger than those of overestimated components. Results of the analysis show that compressor-station project size, capacity, location, and year of completion have different impacts on individual construction component cost overruns.