Kinzua Viaduct hit by tornado 8
Description: A wide range of severe weather moved into western Pennsylvania along a north-by-north west track during the afternoon of July 21, 2003, spawning widespread thunderstorms and several tornadoes. At approximately 320 pm, local time, a tornado touched down immediately east of the Kinzua Viaduct, a structure listed on the National Register of Historic Civil Engineering Landmarks. This 301 foot tall, 2053 foot long, engineering landmark is the jewel of the Pennsylvania State Park system and lies within Kinzua State Park. The park is located approximately 6 miles east of Mt. Jewett, PA in McKean County, north central Pennsylvania, approximately 17 miles south of the New York, Pennsylvania border.
The tornado, classified as a F-1, by the National Oceanic and Atmospheric Administration, on the Fujita Scale with estimated wind speeds exceeding 90 mph, produced a complex pattern of high velocity winds in the immediate vicinity of the structure but nevertheless, left an ordered debris path extending 1 3 of a mile in width. Wind impinged the structure initially from the east due to the counter clockwise rotation of winds within the tornado vortex. As the vortex trailed northward moving past the structure, the structure was re-attacked from the south by a strong inflow of air spiraling into the tornado vortex.
The spectacular collapse of twenty-three of the forty-one structure span was rapid but proceeded in three discrete and separate episodes. The weak-link of the structure, from which the collapse initiated, was the anchorage system at the base of the towers eastern face. Due to a specific hidden deterioration within the anchorage system, the structure was especially vulnerable from high winds attacking from an easterly direction. Anchor bolts at the base of the collapsed towers failed rapidly by one of two modes of separation resulting in separate and distinct segments of the structure becoming airborne upon attack by the wind. The orientation and location
Date Taken: 7/21/2003
City: Mt. Jewett
Country: United States