HUD brake pipe: clear up confusion around pressure and brake force

[Schyrsivochter]

Currently, the HUD element for the brake pipe in the lower right shows 0 % for 5 bar (running) and 100 % for 0 bar (emergency brake), with everything in between simply linear. I understand that this is done in the name of abstracting away the real-world technical details and trying to present a uniform interface. However, I don’t think it’s doing a good job at that currently. Full service braking (3.5 bar) is 30 %. The rest of the scale is almost irrelevant in practice. This is weird.

I think the HUD should either:

1. Use percentage to represent pressure, but the correct way round: 100 % for 5 bar and 0 % for 0 bar. This would still leave a lot of the scale dead (full service at 70 %), but it would at least clear up misunderstandings about ‘charging’ and ‘discharging’ the brake line.
2. Show actual brake line pressure, with a number in whatever pressure unit is sensible (bar, (k/M)Pa, psi, …).
3. Show a percentage of service braking, with 0 % = running (5 bar), 100 % = full service brake (3.5 bar). For emergency braking, display special text, e.g. ‘> 100 %’ or ‘MAX’ or ‘SOS’.

For 1. and 2., the coloured bar indicator should have a visual hint as to where full service brake lies on the scale. For all options, it should also change colour for emergency brake.

Edited April 5, 2023 by Schyrsivochter