The Ansan Line changed factory commuting and links to Seoul. Construction, opening and later through-service within Line 4 are separate events. Ansan, Jungang and Sangnoksu stations serve different industrial, commercial, residential and university districts. Rail access did not eliminate bus transfers, workplace shuttles or unequal walking conditions.
Use dated official records and current notices. Record the visit time, weather, route and—where relevant—tide. Separate heritage from reconstruction, production from sale, workplace from attraction, announcement from completion, and one observation from a citywide conclusion. Stay on public routes and seek consent before photographing residents or workers.