An ambient row-level 'processing/refreshing' indicator built from mechanised sleeper-renewal trains: a crawling gantry crane lifts one old sleeper clear, swings a new one into the gap, and clips the rail down before advancing to the next tie. Old-vs-new is a continuous wear gradient across the 8-row stack, not a binary flag, so it never blinks.
npx shadcn@latest add https://design.helpmarq.com/r/sleeper-renewal-relay.jsonsleeper-renewal-relay