Kinzua Viaduct   Edward Frank
  Jul 22, 2003 19:56 PDT 

Speaking of weather the Kinzua Viaduct at Kinzua Bridge State Park here
in Pennsylvania collapsed last night as a result of winds blowing through
the valley.   

Kinzua Bridge, a 2,053-foot railroad bridge (viaduct), is a famous
Pennsylvania landmark and is designated a National Engineering Landmark.
When this viaduct was built in 1881, it was the world's highest and
longest railroad bridge at 301 feet tall and 2053 feet long. An
excursion train travels through the Allegheny National Forest and to the
bridge.

Due to excessively high winds during a storm on the afternoon of Monday,
July 21, the center section of the Kinzua Bridge span collapsed. No one
was hurt during the collapse, but there is extensive damage not only to
the bridge itself but also the surrounding area. Media coverage
(including photos) can be found courtesy the Bradford Era's web site at
http://www.bradfordera.com

This was one of the top places to go and take fall foliage pictures in
the autumn. They had just started repairing the bridge after years of
neglect this spring. I don't know what the status of the bridge now will
be.

Ed Frank
Kinzua Bridge wind damage photos   Dale J. Luthringer
  Jul 28, 2004 06:05 PDT 

Lee, Ernie,

Here are some shots of the wind damage at the Kinzua Bridge Trestle at
Kinzua State Park on 7/21/03. It blew the middle of the trestle out.
The state was in the process of conducting repairs when this happened.
I'm still not sure if they are going to proceed with this project.

I'm also not sure if I agree with the 'tornado' classification. It
appeared that most of the blow down trees were in generally the same
direction indicating a wind sheer (not sure if I have my terms right).
This is the same recent storm that greatly opened up the Tionesta Scenic
and Research Natural Area a few minutes earlier.


Dale
RE: Kinzua Bridge wind damage photos   Ernie Ostuno
  Jul 29, 2004 00:38 PDT 

Dale,

Trees often fall mainly in the same direction in tornadoes. The reason
is that the forward motion of the tornado adds to the winds of the
tornado that are in the direction of the storm motion and subtracts from
those in the opposite direction. For instance, if a tornado was
stationary with winds of 100 mph, you would get tangential wind speeds
of 100 mph in all directions relative to the ground. Now say the tornado
was moving at 50 mph. The tangential winds in the direction of storm
movement will be 150 mph relative to the ground while those in the
opposite direction would be 50 mph relative to the ground. So most of
the trees would fall in the direction the storm was moving.

The Kinzua storm was rated an F1 tornado. You can read details and see
lots of pics of the Kinzua storm along with a stronger tornado in Potter
County the same day (they are in a .ppt show) at this web site:

http://www.erh.noaa.gov/ctp/features/Severe721.shtml

BTW...they had an F3 tornado a couple weeks ago in Lebanon County:

http://www.erh.noaa.gov/er/ctp/features/July14/Lebanon.shtml