in december 2013 federal safety officials say in the bronx, another metro north jumped its tracks as it barrelled around the curve traveling three times it posted speed, killing four. with more than 11 million passengers traveling along the northeast corridor between washington and boston each year it s become one of the busiest, most complex and technically advanced rail systems in the world. engineering professor george bible says while traveling by train is largely safe passengers should be more concerned about the state of the tracks than speeding engineers. most derailments are caused by equipment error, rail problems are a common one. the rails can fracture from metal fatigue or move around and shift or anything else that moves. the common ones are wheels barings and axels. reporter: co-incidentally,