 In the 1980s , the stations on the Sognsvann Line were rebuilt . The platforms were lengthened from fitting two @-@ car to fitting four @-@ car trains and the platform height was increased . The third rail made it impossible to cross the line at @-@ grade ; an underpass was therefore constructed at Berg station . The station was also redesigned in concrete with steel columns and wooden sheds designed by architect Arne Henriksen . 
 In the 1980s , the stations on the Sognsvann Line <a href='uninflect' title='1'><mark>were</mark></a> rebuilt . The platforms <a href='uninflect' title='2'><mark>were</mark></a> lengthened from fitting two @-@ car to fitting four @-@ car trains and the platform height was increased . The third rail made it impossible to cross the line at @-@ grade ; an underpass was therefore constructed at Berg station . The station was also redesigned in concrete with steel columns and wooden sheds designed by architect Arne Henriksen . 
In the 1980s , da stations on the Sognsvann Line was rebuilt . The platforms was lengthened from fitting two @-@ car to fitting 4 @-@ whip trains and tdaplatform height was increased . The third rail made it impossible to cross the line at @-@ grade ; an underpass was therefore constructed at Berg station . The station was also redesigned in concrete w/ steel columns and wooden sheds designed by architect Arne Henriksen .