To which exits are you referring to? If you refer to exit 7 (from https://www.metropolitan.bg/assets/resourceimages/908/11-npc.jpg), the north one leads to the former trolleybus stop. The stop was moved to the south part of the tunnel (where tram 6 used to run) due to a road accident a few years ago. The staircase to the former stop has been closed on both sides since then (in the pedestrian tunnel they put metal rolling door, on the top side it's covered with a wooden panel).