Pilatus Railway track (note the absence of ballast)
|Opening||4 June 1889|
|Line length||4.6 km (2.86 mi)|
|Track gauge||800 mm (2 ft 7 1⁄2 in)|
|Electrification||1550 V, DC
|Operating speed||9 km/h downhill, about 10 km/h uphill.|
|Highest elevation||2,073 m (6,801 ft)|
|Maximum incline||48 %|
The Pilatus railway (German: Pilatusbahn, PB) is a mountain railway in Switzerland and is the steepest rack railway in the world, with a maximum gradient of 48%. The line runs from Alpnachstad, on Lake Lucerne, to a terminus near the Esel summit of Mount Pilatus at an altitude of 2,073 m (6,801 ft), which makes it the highest railway in Obwalden. At Alpnachstad, the Pilatus railway connects with steamers on Lake Lucerne and with trains on the Brünigbahn line of Zentralbahn. 
The first project to build the line was proposed in 1873, suggesting a 1,435 mm (4 ft 8 1⁄2 in) standard gauge and 25% maximal gradient. However it was concluded that the project would not be economically viable.
Then Eduard Locher, an engineer with great practical experience, proposed an alternative project with the maximal grade raised to 48% to cut the route in half. Conventional systems at the time could not handle such gradients because the vertical cogwheel that is pressed to the rack from above may, under higher gradients, jump out of the engagement with the rack, eliminating the train’s main driving and braking power. Instead, Locher placed a horizontal double rack between the two rails with the rack teeth facing each side. This was engaged by two cogwheels carried on vertical shafts under the car.
This design eliminated the possibility of the cogwheels climbing out of the rack, and additionally prevented the car from toppling over, even under the severe cross winds common in the area. The system was also capable of guiding the car without the need for flanges on the wheels. Indeed, the first cars on Pilatus had no flanges on running wheels but they were later added to allow cars to be moved through tracks without rack rails during maintenance. The line was opened using steam traction on 4 June 1889 and was electrified on 15 May 1937, using an overhead electric supply of 1550 V DC.
The government provided no subsidy for the construction of the line. Instead, Locher established his own company "Locher Systems" to build the railway. The railway was built entirely with private capital and has remained financially viable throughout its life.
The line is 4.6 km (2.86 mi) long, climbs a vertical distance of 1,629 m (5,344 ft), and has a rail gauge of 800 mm (2 ft 7 1⁄2 in). Because of this system, there are no conventional points or switches on the line, only rotary switches (see photograph) and traversers. All railway is laid on solid rock, securing rails by high-strength iron ties attached to the rock, without using any ballast.
The line still uses original rack rails that are now over 100 years old. While they have worn down, it was discovered that this can be fixed by simply turning the rails over, providing a new wearing surface that would be sufficient for the next century as well. The car electric engines are used as generators to brake the car during descent, but this electricity is not reused - it is just dissipated as heat through resistance grids. Originally, the steam engines were used as compressors to provide dynamic braking, since the use of friction brakes alone is not practical on such a steep slopes.
- "A WONDERFUL RAILWAY.". The Register (Adelaide, SA : 1901 - 1929) (Adelaide, SA: National Library of Australia). 2 March 1920. p. 5. Retrieved 13 February 2013.
- "Pilatusbahn (1882)". Landmarks. American Society of Mechanical Engineers. Retrieved 2009-01-18.
- "Pilatusbahn" (PDF). Pilatusbahn brochure. ASME. Retrieved 2009-01-18.
- Book Tramways and Light Railways of Switzerland and Austria, ISBN 0-900433-96-5, by R.J.Buckley, published by the Light Rail Transit Association, 1984.
- Media related to Pilatusbahn at Wikimedia Commons
- Pilatus railway web site
- Scientific American 8/13/1904; The Mount Pilatus Railway, Switzerland