A letter report issued by the Government Accountability Office with an abstract that begins "To install positive train control (PTC)--a communications-based system designed to prevent certain types of train accidents caused by human factors-- almost all railroads are overlaying their existing infrastructure with PTC components; nonetheless, most railroads report they will miss the December 31, 2015, implementation deadline. Both the Association of American Railroads (AAR) and the Federal Railroad Administration (FRA) have reported that most railroads will not have PTC fully implemented by the deadline. Of the four major freight railroads included in GAO's review, only one expects to meet the 2015 deadline. The other three freight railroads ...