After Thusis was reached from Chur, the construction of the Albula Railway began on 15 October 1898. Unlike the Bernina Railway, which was opened a good ten years later, and operated in fully electrified form right from the start, the Albula Railway was still a steam railway at its conception. Moreover, (and again unlike the Bernina Railway), it was intended to be universally available, particularly for the transport of goods. As the steam locomotives of the time were still not particularly powerful, and in order to permit the highest possible speeds, the maximum gradients were restricted to 3.5%, and the minimum curve radius was also generously defined. Thus, the Albula Railway, in the interests of maximising its effectiveness, did not test the technical bounds of an adhesion railway. However, such an architectural style required a variety of engineering structures. So, for example, the viaducts were exclusively solidly constructed. Especially problematical was the ascent of the valley between Bergün/Bravuogn and Preda, where, in a distance of 5 km as the crow flies, a difference in altitude of over 400 m needed to be overcome. To stay within the maximum gradient parameters, the project supervisor, Friedrich Hennings, devised an intricate alignment, which lengthened the line's formation by 12 km. Two curved tunnels, three spiral tunnels, and a number of bridges overcame the engineering problem, by winding the track around like the thread of a screw. On this part of the line, the construction of the 660 m long Rugnux Spiral Tunnels in particular led to problems, because the 4 °C cold mountain water hampered the activities of the workers.
