You've watched a train leave without you
I used to drive to work. Then I moved desks: no parking at the new office, and on weekday mornings the drive takes twice as long as the train. So I opened the subway app I had been using — the live times were often wrong, and the screen wore me out every time. I built this instead.
The goal is simple: clear, trustworthy information the moment you need it, so you can plan today's trip with confidence.
Trains are always a little late
No system runs like clockwork. So this service starts from the assumption that delays happen, and is built around what you can do with them.
Can you catch that train if you hurry through the transfer, or should you let it go and take the next one in comfort? Today's delay changes that answer. This shows you what you need to decide.
What it does
Route search
The routing engine (RAPTOR) is written from scratch. It recalculates using the timetable together with live delays, so it may suggest a different route than other apps or official guidance. That's why an unfamiliar path sometimes appears.
Arrival prediction
A model predicts, for the train running now, when it will reach every station still ahead of it. It uses time of day, day of week, dwell times and similar signals, and retrains every night at 03:45 on the records through that day.
Predicted arrivals and transfer times are weighed together, so the advice leans toward less time standing on a platform.
What you'll find here
- Timetables
- first and last trains by line, direction and day type, and everything in between.
- Yesterday's subway
- how punctual each line was yesterday.
- Yesterday's trajectories
- a full day drawn as one line per train. It's oddly fun to watch.
- Trip planner
- the engine and the model together, finding the fastest train you can actually catch.
Contact
Send bug reports or anything you want to say to hello@startsomething.dev. This is a non-profit project run by one person, not affiliated with Seoul Metro, Korail or any other operator. The data and the maths are described in How delays are calculated, and what is collected is in the Privacy policy.