A major change to the service on the Vestfold Line took place on 29 May 1978, when all smaller stations were closed. Vy introduced its new InterCityExpress concept, which resulted in an increase of patronage by twenty-five percent on the Vestfold Line. From 30 May 1980 the Oslo Tunnel opened, and trains from the Vestfold Line could terminate at Oslo East Station and continue onwards to Lillehammer. The same year a commuter association was started for the Vestfold Line. With the delivery of new B5 carriages, Vy was able to put additional B3 carriages in to use on the Vestfold Line. Automatic train stop was installed from Drammen to Larvik on 18 July 1990 and from Larvik to Skien on 28 November 1991.