A vehicle near the end of its ride will be carrying up to 818 kg (1800 lb) of superheated steam (127 C, 260 F). The 4000 kg (8,900 lb) of onboard batteries and 1800 kg compressor will be dumping heat too. This is 6600 kg of "hot stuff", whereas the entire capsule is projected to have a mass of 15000 kg.

The current design has the passengers in an enclosed capsule in between the compressors and the batteries, with a pressurized air channel running right down the center isle.

Keeping the cabin cool will be a challenge. If that emergency braking is activated, it could get a little warm in there before they are rescued.

I think they may have to quickly repressurize the loop if a car ever gets stuck.