三条轨道的铁路，齿轨铁路，专门用于爬坡的铁路

The article discusses the unique type of railway called "齿轨铁路"， designed for steep inclines， with a notable example being the Piz Bernina in Switzerland. It highlights its爬坡 capabilities， efficiency improvements over steam engines， and cost-saving benefits in mountainous terrain. Despite its usefulness， it is relatively rare.