Climbing past lush alpine meadows to a peak elevation of 2,244 meters, the Brienz Rothorn Railway has operated continuously in the Swiss Alps since 1892. Unlike standard adhesion railways that rely on friction between smooth steel wheels and rails, this mountain line utilizes the Abt rack system, featuring a cogwheel under the engine that meshes directly with a central toothed rack rail. What makes the railway extraordinary today is its commitment to steam traction.
Operating on a maximum gradient of 25 percent, conventional electric or diesel locomotives would face severe mechanical stress, but custom-designed steam rack locomotives offer unique mechanical safety advantages. Modernized lightweight steam engines introduced in the 1990s use specialized boiler designs that keep water constantly covering the firebox crown, even when tilted at extreme angles. Furthermore, steam power provides inherently smooth, controllable torque at low speeds without the risk of wheel spin.
For downhill descents, the locomotives use counter-pressure air braking, taking ambient air into the cylinders and compressing it to create precise, heat-dissipating retardation without wearing out mechanical brakes. By blending Victorian mechanical ingenuity with modern eco-steam technology, the Brienz Rothorn Railway proves that steam remains ideal for mastering extreme alpine inclines safely.