▁established ▁Os lo ▁Sp or ve ier . ▁After ▁the ▁municipal ▁mer ger ▁between ▁A ker ▁and ▁Os lo ▁in ▁ 1 9 4 8 , ▁the ▁Municip ality ▁of ▁Os lo ▁became ▁the ▁major ▁stock ▁holder ▁of ▁Hol men kol ban en . ▁B æ rum s ban en ▁was ▁taken ▁over ▁by ▁Os lo ▁Sp or ve ier ▁in ▁ 1 9 4 4 , ▁and ▁in ▁ 1 9 7 1 ▁dis est ab lished . ▁The ▁private ▁light ▁rail ▁lines ▁were ▁gradually ▁national ized ▁and ▁transferred ▁to ▁Os lo ▁Sp or ve ier , ▁which ▁operated ▁the ▁entire ▁network ▁by ▁ 1 9 7 5 . ▁The ▁met ro ▁was ▁established ▁in ▁ 1 9 6 6 ▁and ▁was ▁operated ▁by ▁Os lo ▁Sp or ve ier , ▁which ▁also ▁operated ▁the ▁city ' s ▁bus es ▁and ▁contract ed ▁the ▁fer ries . ▁ ▁From ▁ 2 0 0 3 ▁to ▁ 2 0 0 8 , ▁the ▁operations ▁were ▁again ▁split . ▁In ▁ 2 0 0 3 , ▁the ▁operations ▁of ▁the ▁tr ams ▁and ▁met ro ▁trains ▁were ▁transferred ▁to ▁O sl ot rik ken ▁( origin ally ▁named ▁Os lo ▁Sp or v og ns d rift ) ▁and ▁Os lo ▁T - ban ed rift , ▁respectively . ▁In ▁ 2 0 0 6 , ▁Os lo ▁Sp or ve ier ▁was ▁split ▁into ▁the ▁infrastr ucture ▁company ▁Kol le ktiv transport produ ks jon ▁and ▁a ▁public ▁transport ▁authority , ▁the ▁latter