Thanks!

- Regarding jams, failures, etc. These should be extremely rare, but in the event, each unit is designed to "disengage" if needed so it's just dumb weight, and modules adjacent to it will be designed to lift it. Then when the train is above ground, the unit can be swapped out for another one and repaired while the system keeps operating. - Yup failsafe mechanisms will be built in as well. - Yeah each unit has its own motor/generator. A power line will enter through the module's axle.