Today a major construction and renovation on a major train corridor between Frankfurt and Mannheim starts. The train corridor will be closed for 5 months. Trains will be rerouted adding 30 minutes of travel time.

Between Mannheim and Frankfurt Airport a replacement bus service is established. The direct connection between Mannheim and Frankfurt Airport will be provided by long distance buses (IC buses). Travel time by bus is 1hour.
Time Table
https://assets.static-bahn.de/dam/jc...Richtungen.pdf
https://assets.static-bahn.de/dam/jc...Richtungen.pdf

See more information here:
https://int.bahn.de/en/booking-infor...nheim-riedbahn