One of the advantages of the british vacuum brake system was that it passively failed into a 'brakes on' state because of atmospheric air pressure. However, th

One of the advantages of the british vacuum brake system was that it passively failed into a 'brakes on' state because of atmospheric air pressure. However, this was about the ONLY major advantage it had, and decades of pro-westinghouse propaganda against it blew the significance of all of the disadvantages* up to be greater than the advantage of fail-safe, and we switched to the westinghouse system. * One of the biggest claimed disadvantages is the fact that vacuum brakes are less effective as you increase altitude, this is a HUGE disadvantage to operating vacuum brakes in the US where a large amount of rail traffic is at altitude, but in the UK where our highest peaks are 3000' and we don't generally run railways to the peaks of those hills, it's almost a non-issue.