Amtrak's pausing use of its Horizon railcars temporarily disrupted service on its popular Borealis line between St. Paul and downtown Chicago. Why it matters: At least some passengers who booked the 7.

The railroad will use bi-level cars on the route in place of single-level cars pulled from the line Wednesday.

An inspection uncovered corrosion on several of the railcars used on the new Amtrak Borealis line from downtown St. Paul to Chicago, leading to the decision to remove them from service on Wednesday and shuttle passengers by bus in both directions.