Hi. I'm not familiar with the line, but the English Wikipedia page hasn't been updated since 2015. The Namuwiki entry claims that construction is tentatively slated for early 2018. The exact route apparently is still under contention, particularly the southern portion. The section in Seoul was meant to follow the original plans of line ten, linking Yeouido to Sinchon and finally terminating at Cheongnyangni, according to the above cited articles. Currently the northern terminus looks to be Seoul Station. In the south, it may or may not even pass through Ansan, and then possibly a further 100km or so further south from there. The articles state that the estimated opening just for the first phase is currently pinned at 2023.