Federal regulators say Union Pacific managers undermined their efforts to assess safety at the railroad by coaching employees on how to respond to questions and suggesting they might be disciplined if they spoke honestly. The Federal Railroad Administration's Karl Alexy said in a letter to the railroad's executives that the problems were so widespread that he had to put the safety assessment on hold. The agency is assessing all of the major railroads in the wake of several high-profile derailments. A Union Pacific spokeswoman said the railroad believes regulators’ concerns center on a message that one manager sent to employees in his department. But the FRA and the largest rail union say employees in several departments received the messages.