CHICAGO --Work on the CTA Blue Line will make it difficult getting to and from O'Hare airport this weekend.Trains will not run between the Jefferson Park and Cumberland stops beginning at 9 p.m. Friday so crews can replace deteriorated rail ties and spikes. Service will remain suspended until 3 a.m. Monday. Red Line riders aren't spared from transit troubles either. Red Line trains aren't running in the subway this weekend. Starting at 9 p.m. Friday, trains will be rerouted to the elevated tracks between the Fullerton station and Chinatown stops. Shuttle buses will be available for both the blue and red line projects. But transit officials are warning that commuters must allow extra time to get to their destination.