The Finstertal Viaduct was built on the karst slope of the Hechenberg (mountain). A "hangviadukt" ("slope viaduct", that is a viaduct built on a slope, requiring much higher supports on the down side that on the up side) was built in the Schlossbach graben. The Kaiserstand Viaduct was built beneath the ruins of Fragenstein. The Gurgelbach Viaduct was built near Reith and the Isar Bridge was built near Scharnitz. Many bridges are similar in size to bridges on the Albula Railway. While stone could be used in Switzerland, concrete had to be used in the Tyrol. The tunnels also had to be lined because of the weak rock. The construction of the tunnels in the Martinswand was particularly difficult and a 17 km long high voltage line had to be built from Innsbruck just for the operation of the machinery. Diesel locomotives brought the rock to dumps. The ingress of water stopped the construction work on the western side of the tunnels and an electric pumping plant had to be installed. The barracks on the eastern side had to be built far below the steep edge due to the lack of space. A funicular railway had to be built to transport workers and materials from the Inn to the site. The smallest radius of curvature of the Mittenwald Railway is 200 m. The maximum gradient of 3.8 percent is significantly greater than the 3.1 percent of the Arlberg Railway, or the 2.6 percent of the Brenner Railway. At Innsbruck West station the line branches off from the Arlberg Railway and reaches in Hötting its lowest point of 580 m above sea level. Its highest point on the Seefeld saddle is at 1,184 m above sea level. This difference in altitiudes is achieved over 19.2 km of line. After this the line descends at up to 3.0 percent to Garmisch-Partenkirchen, where it connects to the line via Murnau and Weilheim to Munich and to the Außerfern Railway via Reutte to Kempten. The Mittenwald railway mainly serves regional and tourist traffic; international long-distance traffic usually uses the Munich–Innsbruck route via Rosenheim and Kufstein (Munich–Rosenheim, Rosenheim–Kufstein and Lower Inn Valley lines).