N8S 50th Anniversary of the Silver Bridge Collapse 12/15/2017 3:00:00 PM - EST 12/17/2017 11:59:00 PM -EST Point Pleasant Silver Bridge Special Event Group N8S Contact : Gail Hodges 6195 Sandhill Road Point Pleasant WV 25550 ab8s@arrl.net 304-675-8035
Was this the bridge featured in the movie The Mothman Prophecies with Richard Gere and Laura Linney ?
As a Licensed Professional Engineer and Bridge Quality Manager overseeing the adequacy of more than 5,000 bridges annually, I want to thank you for remembering and honoring the 46 lives lost in what can be characterized as an unfortunate and avoidable tragedy. Very poor engineering design allowed what should have been a localized failure from gross overloading to become a major bridge collapse. The County not realizing an overload of nearly 300% beyond the original design capacity actually exceeds today's factor of safeties in bridge design. This bridge, along with the failure of the Tacoma Narrows bridge, are still discussed in undergraduate structural engineering courses today - and are a heartfelt lesson to County DOTs to ensure capacity upgrades to existing bridges and/or complete bridge replacements to accommodate increased load demands.
My guess is; in NY State, 30-40%. Each State has its own issues. But the Northeast has to deal with rock salt and freeze thaw cycles too.
Don't know the percentage, but the latest statistic is 55,000 bridges at least http://www.cnn.com/2017/02/15/us/structural-deficient-bridges-trnd/index.html Dave W7UUU
Without looking at any statistical data, I would estimate less than 5% are in dire need of replacement. But another 25% have a remaining service life less than 30 years before they become critical. Remember even though a bridge may show heavy corrosion, broken secondary members, missing rivets, etc., they are designed for significantly more live load than actual. That is the only reason why we do not hear of multiple bridge failures every year in the US. We need to invest in updating our infrastructure, which requires a great deal of capital.
I am really looking forward to the special event "N8S" on 20, 40 and 80 meters this weekend! We have many local events in West Virginia but we don't have many with amateur radio involved and it always a big plus for the local people, state people and allows for other states and even other countries to get involved if propagation permits. Even though the Silver Bridge collapse was a terrible event, this special radio event shines a positive light on the tragedy. I hope all the souls that were lost that day along with their families and friends will find some solace and peace in this 50th anniversary special event. God Bless them each and every one! Tom - WV8CQ
Tom - Most likely the Tacoma Narrows bridge in Washington State. The main span was torsionally flexible and was oscillated by strong wind gusts flowing across the bridge. That created a tremendous dynamic twisting load as wind flowed below and over the span, resulting in collapse. The suspension cables also could not be counted on to provide any stiffness when in compression during the galloping action of the span. Civil Engineers back then did not understand dynamic effects well, which became more pronounced as bridge designs became more efficient and lighter. The ancient Romans who built large heavy stone arch bridges never had that problem, some of which survived major earthquakes over the centuries and are still in operation today.
Yep. The bridge that looked like it really wanted to be a carnival ride was the Tacoma Narrows bridge, known as "Gallopin' Gertie" to the PAC NW gang.
I remember the story of a meeting involving bridge designers. Each gave his area of expertize. Someone asked the last person who he represented, and he said "I represent the wind" Neat. TOM K8ERV Montrose Colo
