Seattle Light Rail Ticker2026

I live about a block from the Link light rail, close enough that with the windows open at night you can hear the trains go by. I ride it constantly, and I'd gotten tired of the little ritual of digging out my phone and opening Google Maps just to check whether a train was coming. What I actually wanted was a screen near the living room I could glance at on my way out the door. So I built one: a live departures board that sits on a tablet on a shelf, showing the next trains in each direction, with a little train that rolls in along the bottom as an arrival gets close. The board looks simple on purpose, but there's a fair amount going on behind it. It's built so that upstream API cost scales with the number of stations being watched, not the number of people watching. Every viewer is served from a shared edge cache, and the app only reaches upstream to the transit API when someone lands on a station whose cache has gone cold, so a thousand people watching one station cost the same as one. It also models the Link network honestly instead of as a flat list of stops: the shared trunk where the 1 and 2 Lines run together, the branches out to Federal Way and Redmond, and the end-of-line behavior at each terminus. The logic that decides what counts as a real, ridable departure is pure and unit-tested. Day to day, none of that shows. You just walk past and see whether it's worth grabbing your shoes. It works for anyone, not just me: you can pull it up, switch to any station on the line, and it remembers your pick for next time.