Some freight rail lines and commuter trains chugging through Gainesville and Hall County are not likely to meet an end-of-year deadline to install safety technology that would prevent locomotives from speeding and potentially reduce collisions, derailments and other accidents. The National Transportation Safety Board reports that positive train control, or PTC, could have saved an estimated 300 lives and prevented about 7,000 injuries over the last five decades if the technology had been in place. A report from the Federal Railroad Administration to Congress last week, however, finds that just 39 percent of locomotives, and 29 percent of passenger trains, will have PTC installed by the end of 2015.