So essentially, you are trusting 2 valves on Mach Tower, Verbolten, Pantheon, and 4 on FF. Those all have pneumatic or hydraulic restraints. Lookup a video on YT from Coaster Bot about how restraints work for more info. It shows how restraints can be locked and released. Essentially, if you watch the video, imagine another solenoid valve inline with the check valve and that will keep the harness from tightening further during the ride. Using normally closed valves means that you have to apply voltage to unlock, then using 2 systems for each harness adds redundancy. Performance Level E (PLe)/ SIL3 safety standards require dual redundant, negative feedback, on each system required to keep someone from being killed.