How does this affect my trip? Board/exit trains on the O'Hare-bound side of the platform at the Clark/Lake, Washington, Monroe and Jackson stations. Trains in both directions will operate on the same track between Grand and LaSalle, resulting in minor delays. Allow extra travel time. Why is service being changed? We are performing maintenance in the Dearborn Subway to ensure that trains continue to operate safely along the Blue Line, and station maintenance at the Clark/Lake and Jackson stations. .