The union that represents train engineers says Union Pacific is holding back on its promises to make their schedules more predictable. These quality of life concerns nearly caused a nationwide rail strike two years ago. The nation's largest railroad is telling the Brotherhood of Locomotive Engineers and Trainmen union that it isn't getting enough work out of its engineers anymore and had to hire more workers than it planned. So Union Pacific wants to tweak the schedule improvement agreements it signed last year. CEO Jim Vena said the railroad will ultimately live up to the deals, but some 60% of its engineers still don't have the new schedules.