It's amazing how hot it is in some places underground, up to 44C. Wow.

At least the workers had air conditioning: http://interaktiv.tagesanzeiger.ch/2016/gotthard-system/

Security of the workers was strictly controlled. Working temperature for example was not allowed to exceed 28°C, which was achieved through cooling installations.

I am curious that if we do get to Mars can we simply dig down or go under a mountain for warmth? You would not need a full on tunnel, just a system similar to geothermal heating

I was curious, too, and found this:

http://cseligman.com/text/planets/magnetism.htm

The author estimates Mars' core temperature to be 5000-7000F, compared to an estimate of around 14000F for Earth. Obviously, the planets' respective compositions are different, so I'm not sure if one could just scale a temperature estimate linearly---but what the heck, this is the Internet and no one's grading me, right? ;)

So the core temperature ratio is 5/14, and the size ratio is 1/3, so:

  (5/14) * (1/3) * 44F = ~5F

That comports with the current consensus regarding subsurface water, because scientists think that it's likely frozen or perhaps a brine (which would depress the solution's freezing point below that of pure water).

Tunneling is probably a good idea anyway, because the surrounding rock will protect and insulate the habitat even if the subsurface temperatures aren't enough to warm it.

Edited: Oh for God's sake, I confused degrees Fahrenheit with degrees Celsius.

For long term stays we'd need to dig underground dwellings on Mars anyways, though not nearly as deep, as the radiation that gets through its atmosphere will be very harmful to anyone living on the surface for multi year time spans.

That's just the Earth's internal heater with a nice insulating blanket on top of it.

I don't read German so maybe this is covered in your article but what does strict planning have to do with getting a TBM unstuck or fraudulent materials? Wouldn't these issues point towards a lack of planning/quality control?

> Wouldn't these issues point towards a lack of planning/quality control?

If your car engine breaks down you did a bad route planning?

There are things that can't be planned for.

One of the major problems detected was the fact that they had to drill through dolostone, which is a huge technological challenge. When mixed with water it results in a soupy mixture, which is almost impossible to work with in drilling a tunnel.

The did exploration drillings in 1993, but engineers where still pretty worried.

It was only in 2008 that the engineers lost the last of their concerns.

Such a huge project comes with technical uncertainties. What do you want to do about it?

Well if they caught it then there was quality control after all, wasn't there?

As I note, I can't read German so I don't know what or when the fraudulent materials were caught. If they weren't caught until they were installed then no, there wasn't proper quality control.

My more important question is how does catching fraudulent materials have anything to do with strict planning?

Controls are built into the process from the onset.