Pilatus Railway, Alpnachstad, Esel Summit, Obwalden, Switzerland

History
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.