U4 (Hamburg U-Bahn) · Relations URL: https://knowledge.ivjn.us/en/concepts/ubahn-hamburg-u4/relation.html At 11.9 km in length and with 12 stations, the U4 is the shortest and youngest line of the Hamburg U-Bahn; it was opened in 2012 and runs from Elbbrücken via Jungfernstieg and Hauptbahnhof Nord to Billstedt. Page 1 / 0, 0 total