Most trains can't climb slopes steeper than about 10 percent. The metal wheels lose their grip and spin against the metal rails. Some areas of Pikes Peak, a granite giant in Colorado's Front Range, are much steeper than that. So, over a hundred years ago, engineers built a different type of railroad, one with a toothed track down the middle. An engineering history record kept for the American Society of Mechanical Engineers states that the line is the highest railroad in the United States and the highest rack railroad in the world. It has carried more than three million passengers to the summit since 1891, without a single passenger death.
The idea came from a miserable mule ride
