Calgary has also horribly cold winters which forces a lot of people to stay inside most of the winter. Maybe someone should do a correlation study with days/year where temperature doesn't exceed 20F (I know correlation != causation but at least it's one more hypothesis) . I personally feel depressed on days where I have to stay inside all day, and just taking a walk outside for half a hour uplifts my mood quite a bit.
Can we get a source for the $100M per kilometer figure? The NYC subway system has 373 km of tunnels, 60% of which is underground, which would translate to roughly 22 billion dollars just for the digging... that just seems way too high to me.
2nd Avenue subway [0] requires about 8.5 miles worth of tunnels (several hundred feet of which were already dug back in the 70's) and it's budget is $17 billion. Of course that whole cost isn't just for digging tunnels, but it's a clear indication that digging tunnels (especially in dense urban areas) can be extremely expensive.
There is a very large difference between building complex tunnels and a simple hole in the ground. The cost for drilling a straight exploratory/mining hole was 10 Million/km in the 70's and 80's[0]. I can easily imagine this being cheaper by a factor of 2-5 with current advances. Not to mention this concept has a lot of synergy with mining companies.
There is a difference, but it's not necessarily large for deep drilling. Once you start drilling large diameter holes deep into the ground, you have to shore up that hole to prevent it from collapsing in on itself. For wells or expiatory holes, water or slurry is used, but that's not an option in this case, so there will need to be a casing involve. Installing that casing so that the pieces line line up perfectly is a complex endeavor (not impossible, it's been done, just not straight forward as "drill a hole")
