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This is the official line scheme for when the tunnel is finished.
Note that all lines in the central pedestrian zone are underground (dashed) and a new surface line will be build at the southern end of the inner city (lines 6/7).
However there will be less trams overall in the city, as the tunnel doesn't have the same capacity as a surface line.
The mentioned 3/4 loop will be broken up, meaning the southern city will have worse access to the inner city.
Instead, a 6/7 loop will run on the newly built surface line (though line 7 is set to only run during peak hours). Also the junctions of this loop will be away from the main east-west line in the tunnel. E.g. going from the western suburbs to the ZKM line will then require two interchanges at Europaplatz at Karlstor, which are just one station apart.
Lines 4 and S2 from the east are going to be rerouted to get to the tunnel ramp, eating up any time advantage a fast tunnel line might give.