Service connecting branches of 3/4 Lines
According to estimates - the busiest connecting branch in the Petersburg metro at rush hour, train intervals are sometimes compressed to 15 seconds). Surrounded by many underground structures, it contains a branch with a train maintenance point. There are legends about the tunnel to Smolny (mayor's office of Saint-Petersburg), but there is no evidence of this.
The tunnel starts from station Ploshchad Alexandra Nevskogo-1 with the cross-ramp camera. Right where the train is - a working tunnel. Layer to the right - arrow into another working tunnel.
The third way (if you look back) is the beginning of the connecting branch. Further along the tunnel there is another arrow. On the right, where the train is standing, is a dead end with a maintenance point, on the left is the continuation of the connecting branch:
The turn of the tunnel is located exactly under the Monastyrka River and the Holy Trinity Alexander Nevsky Lavra.
At the beginning of the turn, there is a small passage, concreted at the end.
And then a flat straight line to the station Ploshchad Alexandra Nevskogo-2.