@techreport{BorndoerferKarbstein2015, author = {Ralf Bornd{\"o}rfer and Marika Karbstein}, title = {Metric Inequalities for Routings on Direct Connections with Application in Line Planning}, institution = {ZIB}, address = {Takustr. 7, 14195 Berlin}, number = {15-07}, language = {eng}, year = {2015} }