An automatic braking system for railroads is either in advanced field testing or operational on 98 percent of the required route miles mandated by Congress, according to a recent assessment by federal regulators. The Federal Railroad Administration announced May 15 that positive train control technology is on 56,541 route miles of the nearly 58,000 route miles mandated by Congress. Based on data compiled by FRA as of March 31, the technology had yet to be activated on about 1,100 route miles. Congress directed railroads to fully implement PTC systems by Dec. 31, a two-year extension of an initial deadline.