Passenger tunnel A/B
If you are changing between piers A and B in Terminal 1, you can use the passenger tunnel.
Terminal change via shuttle buses
+ The yellow shuttle buses are a convenient way to transfer between terminals.
+ The stops are located in front of Terminals 1 and 2 and at the P36 bus parking lot for long-distance buses.
+ They leave every 10-15 minutes (depending on the time of day) and operate daily around the clock (24/7).
+ The shuttle is free of charge.
Terminal change via SkyLine
+ If you have to change between areas A, B, C or Z (Terminal 1) and areas D or E (Terminal 2), the signs will take you to the free SkyLine.
+ It leaves every 2-3 minutes and operates from 5:00 a.m. until 11:00 p.m.
Passengers can board and alight from the public area as well as from the transit area.
The stops are located in:
+ Terminal 1, A/Z (transit area)
+ Terminal 1, B/C (access via departure hall B on level 2)
+ Terminal 1, C (transit area)
+ Terminal 2, D/E (access via Shopping Plaza on level 3)
FRA map is here.
Source for the data: Lufthansa.