Transportation in South Korea

South Korea's transport runs on two tiers: the high-speed rail network (KTX/SRT) that stitches cities together in a couple of hours, and the dense metro-bus combo that owns every urban trip. In Seoul, Busan, Daegu, Daejeon and Gwangju the subway lines are spotless, signed in English, and cheap enough that locals swipe without thinking. Buses fill the gaps, color-coded (blue for trunk, green for feeder, red for express) and all accept the same T-money card you'll buy at the first station kiosk. Skip the single-journey paper tickets. The card also works in taxis and convenience stores. For airport access, Incheon has the AREX express (non-stop to Seoul Station, a splurge but half the time) and the all-stop commuter version that's a fraction of the price. Gimpo connects straight onto subway lines 5 and 9. Taxi queues are metered and honest. But increase after midnight, if you land late, the bus routes run 24 h and cost little more than a coffee. One rookie error: don't buy an SIM and a transit card separately. Most convenience-store kiosks bundle them and you'll save the queue.