choo choo from me to you ❤🚉

Imagine if the railroad questline saw you clearing and connecting the tunnels to a home base

this is why i use mods like subway runner to make all the subways interconnected, it would've been really useful in survival to be able to use the tunnels as an alternative travel route to get to certain locations

I imagine the reason why the subways have both a monorail and a more traditional track is because the trains originally used the floor tracks before the city upgraded to a more sophisticated monorail system. The old tracks were left behind either for maintenance trains to run on or just to cut the cost of tearing them up

There is a subway station under the airport, if you join the Brotherhood, Captain Kells will assign you the task of finding who is stealing the supplies, you will eventually end up under the airport in which there is a subway tunnel and yes, it is colored blue. The entry is on the side behind one of the jet wrecks.

I also want to add, in the the side quest that you dig to steal from Diamond city supplies, you will end up digging into the Boston metro system, in one of the sections, there is  regular train cars loaded with cargo, so the metro system is probably dual purposed.

Subway runner is a great mod I wish every single subway system was connected and the railroad side quests were focused on clearing them out so they have more ground to cover

The simplest explanation for there being traditional rails underneath the subway monorail system is that they are vestigial remnants of the old Boston network, whenever the subway system switched to monorail they left the existing tracks in place because it would've been significantly cheaper to just leave them

8:00 What I’m assuming is the railroad tracks were meant to be leftovers from the old subway trains that still used them, when the new trains were designed they installed the monorails and left the tracks unaltered because they caused no issues/could be used in emergencies

Some big mods like Frost added their interpretation of FO4 subway system back into the game, and it is a game changer.

You can travel most of the city through there without getting insta KOd by radiation. Along the entire way you have settlements, a running market, two entire factions fighting a war against each other Metro 2033 style, lots of side dungeons and industrial facilities and rooms where you can detour... and big horror areas and side track lines where nobody goes (for very good reason). You don't go near Malden, the airport, or the southernmost stations if you want your game to continue, but the there are a lot of spots to explore.

But because it is Frost and takes place just a few years after the big boom, they made like only one of those spots an actual friendly location (also the only NPC settlement in the entire mod IIRC), the rest are just enemy dungeons.

What's interesting is that the monorail is baked into the double-level elevated highway assets themselves, so as a level designer you can't opt in/out of having a monorail. Unfortunately there's no separate monorail asset, so you can't repair and make it consistent. That is why it feels so tacked on and the designers mess it up with highway intersections. It's such a cool concept, and I loved how it looked in the Fallout 4 intro, it's such a shame the monorail was never more developed. Especially since the monorail seems to also be used in the metro, it would be so cool to have the elevated monorail go underground in sections. The metro assets also don't have any curved tunnels, so you can't make a curved tunnel. The only tunnel assets that seem to curve actually only go left/right up/down and then back to straight in the same direction. It's annoying as a modder if you want to build a better metro because the assets are lacking

The subways of F4 always seemed like wasted potential especially compared to 3

5:59
The Cambridge crater bomb, which you suspected to have been a bunker busting subteranian nuke, would have caused a large shockwave through the ground. Since ground is denser shockwaves in it travel faster meaning that the nuke would cause most tunnels to collapse

15:46 you note that the green line would extend to Medford/Tufts. It's important to note that when fallout 4 came out, GLX, the green line extension that includes Medford/Tufts, didn't exist. As of 2015 when FO4 was being created, the chances of GLX happening were somewhat in question, and the project was still in the very early planning stages. GLX & Medford would open in 2022.

There is a subway under the Airport. You have to traverse part of it while investigating the missing supplies for the Brotherhood.

Separately, I believe the removing of a traversal subway system was a consequence of Fallout 3's system. You said it yourself, it eventually became annoying to use, so instead of streamlining the whole section, they just scrapped it

Funny thing is, Skyrim has a subway adjacent locale in the form of blackreach. there are a handful of dwemer ruins that will take you below, only to offer a good selection of options for where you want to resurface.

As a lifelong Boston resident, here’s my answer for the metro having ground tracks and a monorail line above. Today,    all trains are powered by an electrified “third” rail on the ground. But originally, some lines like the Blue line ran on rail tracks but were powered by electric wires that ran above the train. Those trains used an electric rod to touch the electric lines similar to bumper cars. I say that Fallout 4 uses that system. Running on tracks but powered by a rail above. And thanks for this great dive on my beloved MBTA. I too wish that you could explore the tunnels between the stations. That would’ve been cool.

The railroads in Boston were, indeed, functional prior to the events of the game, as the game begins in the pre-war era.

If you installed a suspended monorail above a historic railroad track, it would be more cost effective to leave the track in place rather than digging it up plus people might get pissed off if you destroyed the track

You missed the station in the north sector of Vault 88.
It's green line and has a manhole that opens to Milton General Hospital.
Which would suggest its either a subway station for the hospital, or maybe part of west Roxbury.

the obelisk demands sacrafice