Drawing 1: Ten inclined planes on
the Allegheny Portage Railroad.
The railroad portage over the Allegheny Mountains was crucial to the Pennsylvania Main Line. It joined the system's two great canals into an efficient artery between eastern and western Pennsylvania. Passengers leaving Philadelphia in 1840 could reach Pittsburgh in 4 days instead of 23.
The engineering was simple in principle. In the canal basin at Hollidaysburg, the packet boat sections in which passengers had travelled from Philadelphia were floated onto railroad cars for the portage. They were hauled from the water by stationary engines, then pulled by locomotives at about 15 mph over the long grade to the first incline. In a small shed at the foot of the incline, workers hitched three cars at a time, each averaging 7,000 pounds, to the continuous cable that moved over rollers between the rails. This cable was pulled at about 4 mph by a stationary steam engine beneath a large shed at the top of the incline. When possible, the operators used cars descending on the other track to counterbalance those assending, lessening the strain on the engines. On the near-level grades between inclines, the cars were drawn by horses or locomotives. The process was reversed on the other side of the summit.Questions for Drawing 1
1. Locate Johnstown and Hollidaysburg on both Drawing 1 and on Map 1. Which visual shows more detail?
2. Using the information in Reading 1, trace the route of the Allegheny Portage Railroad. Which part of the route seemed more treacherous?
3. Using Drawing 1 and the Reading 1, describe the topography: a) between Johnstown and inclined plane no. 2; b) between inclined plane no. 2 and the summit; and c) between the summit and Hollidaysburg.
* The drawing on the screen has a resolution of 72 dots per inch (dpi), and therefore will print poorly. You can obtain a high quality version of Drawing 1, but be aware that the file will take as much as two minutes to load with a 28.8K modem.