Heads up:
Today and tomorrow Deutsche Bahn will start the first two major construction sites to modernize their long-distance rail transport network (see overview page of planned measures).
It may influence the travel to / from Frankfurt Airport with Deutsche Bahn.
Affected routes:
- Frankfurt – Mannheim: see details; this is one of the most used train line in Germany
- Cologne – Frankfurt: see details
Summary: travelers will need more time on these routes and have less choice of connections. The direct connection between Mannheim and Frankfurt Airport will be provided by long distance buses (IC buses). Local trains will partly be affected by bus replacements.
In 2024 twelve more projects will be proceeded (see link to overview page of planned measures).
EDIT after initial posting: The major network construction projects of Deutsche Bahn until 2030 you can see in an illustrated map for ADAC (German AAA).
Of course the information in DB journey planner is updated.