"Lack of manpower" caused Metra to cancel six UP West trains Monday morning.
Union Pacific spokesman Mark Davis told NBCChicago the cancellations were caused by a shortage of engineers. It's not a labor issue, Davis insisted, but a mix of vacation, sick and personal days.
"It was a culmination of several things," Davis said. "It was engineers that are on vacation, those that are away on family leave. Some of them were in training and we did have a few that were ill today."
UP usually keeps six engineers on hand, but on Monday, Davis said even those extras were being used. The line's management team is investigating how to avoid this situation in the future.
The following trains were canceled: outbound trains 13 and 17, as well as inbound trains 10, 16, 24 and 28. Other trains on the UP West line were delayed.
Commuters on the UP West were being told "equipment problems" caused the cancellations.
"To have a situation where all of the components come into play at once is highly unusual," he said.