Another major goal of the metro was to connect the suburban lines on each side of the city through a tunnel, specifically the Common Tunnel. With the opening of the metro in 1966 only was needed to establish a connection, yet not until 1977 did the new station Sentrum open, allowing the T-bane closer access to the city center. However, leaks forced the station to close in 1983, and not until 1987 did it reopen, this time also as the terminus for the western trams. Through running could not be accomplished until 1993, when parts of the western network had been upgraded to metro standard.