The first high speed railway in Korea was opened to traffic on April 1, 2004 and the second phase will be opened on November 1. 2010. Many technical problems that occurred during construction have been solved. In its early period of project, difficulties were encountered in design, construction of high speed line. because most of Korean railway engineers were familiar only with conventional railway. Now they understand the various phenomena occuring during operation of the KTX and have accumulated extensive technical knowhow. Valuable experiences and knowledges that have been obtained from frials and errors will lead to further improvement for the future project.