Not sure if anyone ever bothered, bt i know it is a common complaint that the metro tunnels of Capital Wasteland is a pain in ass, it is confusing, stink, and fully packed with feral ghouls, etc. Many ppl simply fast travel or never go down one
It took me a whole sunday afternoon, about 4 or 5 hrs, to wipe out ALL hostile creatures underneath the wasteland, include a million feral ghouls, reavers, some mirelurks, and rats. Since creatures indoor do not re-spawn, there is nothing left now (at least i think)
It doesn't serve any quest purpose, bt psychologically you do feel a sense of great ease since you know the feral ghouls is only history, I may missed few lucky bastards, and there are some ghouls above the ground in Dupont area etc may re-spawn, bt that's really minor.
Didn't feel very hard while the character is level 30, plus an indestructible Dogmeat that I used him as a tank lol
I used my Flamer to clear the tunnels, I need them clear to access to my incidental Player Housing in Arlington. I got the flamer from the Gary 32/23 glitch to get all my equipment out of the simulation. Fantastic, I now have a clear road from GNR-Rivet City-Arlington Cemetery-This place where I train my companions due to the presence of super mutants+Talon Mercs, not bad.