Elon Musk's plan for a pressurized "Hyperloop" transport system between San Francisco and Los Angeles contains a contingency in case there's a crash.
Musk doesn't use the word "crash" specifically, but there's a whole section devoted to safety, depressurization, and structural integrity.
And the diagrams note that the passengers are wearing seatbelts. There is only one reason to wear a seatbelt, of course — crashes.
Musk starts by saying that the system will likely be safer than other forms of transport:
The system is immune to wind, ice, fog, and rain. The propulsion system is integrated into the tube and can only accelerate the capsule to speeds that are safe in each section. With human control error and unpredictable weather removed from the system, very few safety concerns remain.
In many cases Hyperloop is intrinsically safer than airplanes, trains, or automobiles.
But in the event of a serious incident, passengers may lose oxygen — they're inside a sealed tube, after all. So Oxygen masks would be deployed:
In the case of a more significant depressurization, oxygen masks would be deployed as in airplanes. Once the capsule reached the destination safely it would be removed from service. Safety of the onboard air supply in Hyperloop would be very similar to aircraft, and can take advantage of decades of development in similar systems.
The passenger capsules — which coast through the tubes, pushed in front of a column of pressurized air — are coasting for much of their journey, so they have emergency brakes and engine-driven wheels in case they are stranded or need to avoid hitting a stranded Hyperloop car:
In the unlikely event of a large scale capsule depressurization, other capsules in the tube would automatically begin emergency braking whilst the Hyperloop tube would undergo rapid re-pressurization along its entire length.
Once all capsules behind the stranded capsule had been safely brought to rest, capsules would drive themselves to safety using small onboard electric motors to power deployed wheels. All capsules would be equipped with a reserve air supply great enough to ensure the safety of all passengers for a worst case scenario event.
