Controlled Demonstration of a Tank Trailer Vacuum Collapse by Wabash National

Evacuation isn't a problem at all. This is what happens to a failing vacuum tube. [this video] (note that the hyperloop will be a significantly higher vacuum. There would actually be little point in depressurizing a pipe to the level shown in the video. I hear this was done on mythbusters as well) I think you'll agree after seeing the video: attempts to let people get out of that ... there's just no point. They'll be folded into an accordion before you can say cappuccino. Literally. Failures will propagate along such a pipe at close to the speed of sound. You wouldn't get through the first "c" of cappuccino. You should restate the problem: the problem is the same as with trailer vs car crashes: pulling the various flattened and crushed together pieces of different people apart in a way that you'd be reasonably certain the right liter of goop recovered goes into the right casket, ideally with as little pieces of the pipe in there with them as possible. An extra issue is that every way you might recover also fails given the forces involved. Let's say you let air in ? Well that's going to form a wall of air that'll hit with a speed, force and acceleration that is guaranteed to kill every passenger, just from the acceleration. More likely that too will fold them into an accordion. This problem is like attempting to keep a plane intact during a crash. It can't be done, and even if you should succeed, there's no point: everyone inside will be dead from the acceleration.

I'm very skeptical of this concept because of how difficult it is to build and maintain a massive vacuum chamber that will experience that level of stress over its lifespan. As far as I know, the largest vacuum chamber in the world by volume is the SPF at NASA [1], which is only 37x30m in size. Building such a vessel hundreds of kilometres in length that would have bullet trains going through it multiple times a day seems dangerous and impractical. A single leak anywhere in the tube could potentially cause explosive pressurization [2]. Maybe the Hyperloop is this century's Monorail... [1] [link] [2] [this video]

[this video] Here is a steel pressure tank imploding. It was under only 14.5ish psi. The Titan would have experienced HUNDREDS of psi. Also, it's pressure hull was made of Carbon Fiber, which is notorious for failing catastrophically with zero warning, whether due to a manufacturing defect like a simple nick, or just going beyond what it could physically withstand. The vessel was NEVER tested to 4000 m. It was probable that it was always going to fail at the depth needed for the titanic. There was no warning for the crew and passengers. One instant they were descending just fine, the next they are human bisque.