OMAHA, Neb. (AP) — The nation’s largest railroad union wants federal regulators to do more to ensure conductors are properly trained in the wake of two recent trainee deaths in Maryland. The union that represents conductors wants the Federal Railroad Administration to establish clear standards for how long new employees are trained and who mentors them to teach them the craft after they finish their classroom training. The agency hasn’t required the railroads to make changes, but it has urged them to improve training including in a new letter sent to all their CEOs this week. CSX and Norfolk Southern have both recently announced agreements with the union to improve conductor training.