Waveform distortion is a serious problem in higher-frequency signals on printed circuit boards (PCB). In order to overcome this problem, the segmental transmission line (STL) has already been proposed. However, the STL requires segments of wide-range widths. The wide-range line-width impedes higher optimization of waveforms and it also causes cost-increment in the PCB manufacturing. In this paper, we propose a novel STL with variable length segments in order to overcome the difficulties in previous work. We also develop a design methodology using a GA to determine the parameters for the proposed STL. We apply our new STL to the clock line in the actual PCB, and show its effectiveness compared with the previously proposed STL.