featherbedding: jobs without responsibility, so they're basically solely to give someone a paycheck

TBM: Tunnel Boring Machine, the main piece of equipment in building deep tunnels

cut-and-cover: a way of building tunnels that consists of building a trench and then putting a roof over it

fixed-guideway: basically, anything that's a railroad or has similar constraints (such as a monorail)

switch fouling: fouling a switch means to have a train over it so that you can't change which direction it goes to

headway: time between successive consists. 5min headway means one train arrives every 5 minutes

consist: a set of cars that all move together as a fixed unit

I think that's all the terms that people might not immediately understand.

TIL featherbedding ~= sinecure