The most frequently delayed air route in the country is the fifty minute hop between South Bend and Chicago's O'Hare. That South Bend gets slammed by lake effect snow each winter has a lot to do with it.
A fifty-minute, approximately 100 mile plane trip, however, doesn't make much sense. And there's the beginning of a better way to get South Bend passengers to O'Hare.
In my experience, it's common for some South Bend air passengers (there are cross-country flights out of the airport) to begin or end their journey on the South Shore Line.
South Bend to O'Hare or Midway, though, is a pokey proposition, with a change from the interurban to the L in downtown Chicago, with several blocks walk or a costly taxi ride, and the L service to the airport is on normal-service, all-stop trains. That's where Chicago's Cross Rail project ought to come in.