Metra is warning commuters to leave extra time for the morning commute because of the cold weather.
In a statement, Metra says trains are likely to be delayed with subzero temperatures and wind chills forecast for this week.
Trains will be operating at reduced speeds if necessary to reduce stress on the rails. Agency officials say cold weather also usually leads to slower boarding.
The agency had troubles with switching earlier this month during a blast of cold weather. Also six passengers were hospitalized with minor injuries when a commuter train hit a "bumping post" at a downtown station.
Metra says personnel will work to keep switches operational and have trains ready for service. However, it's difficult because work on switches must be performed outside.