Right at the start, the Mountain Line faced a very steep climb, at a rate of 20-25 per thousand. In particular, the turn at Shihliufen, which winds 180 degrees in only 300 meters, was the stretch of TRA track that had both the steepest slope and sharpest curve.
坡陡車緩舊山線火車一開出，就是艱難的大爬坡，一路陡峭的坡度在千分之二十到二十五之間，尤其是彎度曲率半徑只有三百公尺的十六份彎，更是台灣鐵路坡度、彎度都居第一的路段（不包括林務局所管轄的阿里山鐵路）。