 Berg is served by line 6 on the Sognsvann Line , operated by Oslo T @-@ <unk> on contract with <unk> . The rapid transit serves the station every 15 minutes , except in the late evening and on weekend mornings , when there is a 30 @-@ minute <unk> . Travel time along the 6 @.@ 1 @-@ kilometre ( 3 @.@ 8 mi ) portion to <unk> in the city center is 11 minutes . 
