HISTORY specifc to this model: Prototype built and commissioned into service in 1833'  Proclaimed by the Pennsylvania Railroad management to be the first railraod viaduct built in the United States. This claim is suspect since the B & O Carrollton Viaduct was operating in 1830.
Such was the "love" between the Pennsy and rival B & O! 

The "BIG" viaduct stood seventy (70) feet tall from riverbed to railhead. Local rough cut sandstone was used in the construction. Stone blocks ranged from 12 - 25 cubic feet each. Such a massive structure was built to last until the "last" day!   Act of God...Mother nature stepped in on May 31, 1889 and totally destroyed the enitre viaduct as a Ninety (90) foot Wall, many millons of gallons of water and tons of debris, hit the Viaduct at fifteen (15) MPH.

The "BIG" viaduct became a casuality of the Terrible Johnstown Flood!!  A temporary wooden testle erecthed to reopen the mainline. The Big viaduct II two arch degn was built to replace the original sing arch span. BV-II remains in active revenue service for NS Corp as of 2006.