Factamero_ on Instagram: "Berlin's U-Bahn carries 1.5 million people daily. A 4-second delay at one station, multiplied across 173 stations and thousands of daily runs, snowballs into schedule chaos. Tokyo went further: stations play melodies instead of buzzers because harsh sounds cause panic and slow boarding. Moscow's metro uses a male voice for city-center-bound trains and female for outbound, so blind passengers can navigate without a map. London's "Mind the Gap" voice became so iconic that