Saturday, July 30, 2011

Views 1833 Conemaugh Viaduct - Mineral Point

This is a Google Maps, "Bird's Eye" or low level oblique view of the Conemaugh River Viaduct located at milepost 267.2 (40.368422N79.819044W). The current stone viaduct was built to replace the 1833 Conemaugh Viaduct built by the Commonwealth of Pennsylvania for the original or Old Portage Railroad. The Portage Railroad was built between Johnstown and Hollidaysburg, PA to connect the the western and eastern sections of the Pennsylvania Canal that were also built by the Commonwealth of Pennsylvania to connect Pittsburgh and Harrisburg. The 1833 viaduct was destroyed when the South Fork dam, also built by the Commonwealth of Pennslvania as part of the system of canals and railroad failed May 31, 1889. The wall of water traveled form right to left in the foreground then left to right to the site of the viaduct in the center of the image. The viaduct was swept away.

This portion of a map drawn for the Blair County Historical Society in 1941 indicates that the section of PRR mainline now owned by NS continued at milepost 267.2 to use the right of way ROW for both the Old and New Portage Railroad about  to milepost 267.8. This is the oldest section of the Pittsburgh to Harrisburg line. 

When the 1834 Old Portage Railroad was rebuilt as the New Portage Railroad  beginning July 29, 1852, by the Commonwealth of Pennsylvania in order to avoid the incline planes of the old with a new continuous railroad from Johnstown to Hollidaysburg, PA; the viaduct remained part of the ROW for the New Portage Railroad.

 Photograph of the 1833 Conemaugh Viaduct built for the Old Portage Railroad, used by the New Portage Railroad and then Pennsylvania Railroad  until 1889 when the viaduct was destroyed by a flood caused by the collapse of the upstream South Fork dam.

"The viaduct over the little Conemaugh ... has a semi-circular arch of 80 feet. The height of the abultment walls from the foundation to the springing line of the arch, is 29 feet. do. from the low water 20 feet. The rise of the arch is 40 feet....Cost about $52,000."

In today's dollars it would be roughly $1,390,000.00.  See:

The image below is an 1875 woodcut of the viaduct as used by a PRR Pennsylvania Railroad train.

See "The Allegheny Old Portage Railroad 1834-1854," by Mahlon  J. Baumgardner and Floyd Hoenstine."

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