Landvermessung U-Bahn

Rules:

Draw a totally connected loop network through the centers of some cells, which may branch or turn, but may not have any dead ends.

A clue outside the grid indicates how many times the corresponding line shape (i.e. a cross, branch, straight line, or turn) appears in the corresponding row or column, irrespective of the line shape’s rotation.

A clue inside the grid indicates the length of the smallest loop (that does not touch or cross itself) on the network that touches all non-empty cells surrounding the clue. If the clue is an infinity sign, then no such loop exists.