By some strange coincidence, those odd looking imperial measurements have metric equivalents that happen to be fairly close to “round numbers”:
114.17 inches = 2899.918 mm or 2.9 meters
122.05 inches = 3100.07 mm or 3.1 meters
It’s almost as if the trains and their tunnels were designed based on the metric system. /s
Well no wonder they screwed it up. As mrs. rktman would say, “Sure that looks like a foot.” As she rolls her eyes at me measuring something.
It's not a metric vs. imperial issue really. The numbers they used are what they are. The real question that hasn't been asked or answered in any of the articles I've read on this issue is "How wide are the tunnels"? The safety envelope was based on the old trains. They assumed x for sway, so they needed y for safety, but they don't say how much room they actually have in any of the articles.
Are they just sitting on their butts saying the new trains are too wide based on the old safety envelopes, or do they actually know the tunnels in question are too narrow. The safety envelope and the tunnel width are two separate deals. That would also imply track separation between trains, not just side-to-side/ceiling clearance within the tunnel walls.
Also, does it affect every line, or only certain lines? These things matter.