User blog:WildBrick142/Old Subway Tunnel

i got a problem... i want to go into the old subway tunnel but i want it to be seen and to not fall in blue hell and keep respwning above blue hell and falling in it again.. i read on Bringing the House Down trivia that There is a glitch in the game where before and after the mission is complete, part of the tunnel can be explored if the player can jump onto the ledge that is across from the subway platform. From there, the player must travel left until they fall through, falling into Blue Hell and eventually into the tunnel appearing in the mission. Note that only the entrance of the tunnel can be explored as the rest of the abandoned subway doesn't appear to be there, the only thing that is there is Blue Hell and a few objects that were in the mission." i dont understand this and i tried everything to do this

and note that i want to access it after/before the mission, not during because that would be kinda boring....