A large bridge in Pittsburgh (Liberty Bridge, on the north side of the Liberty Tunnel) was damaged by fire a week ago. It was being re-habbed, but was open to traffic, and a welders torch caused a plastic pipe to catch fire, and then a tarp. The heat of 1200 degrees damaged a major component which almost caused the bridge to collapse.
This is a MAJOR bridge, I travel over it all of the time, where I live it is the main route into the city. Really interesting story about it in the local paper...
The story linked above said the following: " A crew used a surveying device known as a robotic total station. The device uses mirrors, a laser, and a series of sensors to test every half hour 24 hours a day for any movement of the bridge...The good news is the bridge has moved less than 1/1000th of an inch since the fire".
Ridiculous, even 1/1000th of a foot would not be detectable, but I imagine that is what was told to the reporter and misquoted. I wonder if the people doing the monitoring have any idea about what they are doing.
Contractor is being fined $200,000/day while it is closed. They are hoping it will reopen on Monday.
Here is a picture now...
Tunnel was built in 1926 (longest highway tunnel at the time) and the bridge in 1928.
Somebody will be taking a huge financial hit from this.
I'd guess the reporter was told .01 foot or perhaps .001 meter, but botched the reporting. Or it could have been a field crew over excited about their work making the news. Or... (see the post about the robot locked on the backsite!). With no load on the bridge it'd be pretty stable, but you'd still expect a couple hunerts between the hot and cold parts of the day.
not 1/1000th of an inch, but LESS than 1/1000th..........
I'm not an engineer, but aren't bridges supposed to move?
specially metal ones.....
BajaOR, post: 390337, member: 9139 wrote: I'd guess the reporter was told .01 foot or perhaps .001 meter, but botched the reporting. Or it could have been a field crew over excited about their work making the news. Or... (see the post about the robot locked on the backsite!). With no load on the bridge it'd be pretty stable, but you'd still expect a couple hunerts between the hot and cold parts of the day.
I thought bridges were designed to have sway same as hi-rise construction
Yep, reporters don't do surveying numbers well
When Dr.Senna of LSU (now NGS) installed our local CORS station, a very good reporter from the New Orleans paper did a piece. He contacted me about the impact for local surveying.
I explained to him the benefits of attaining Lat/Long and elevations in a timely matter and the cm accuracy for elevations and better for Lat/Long.
Well, he quoted me that surveyors could attain instantly an accuracy of 1 mm for elevations. I kept a low profile for awhile from embarrassment.
Whats that old joke, "How many thousandths are there in an inch?? I Dunno, but there must be millions of them!!"
Robert Hill, post: 390344, member: 378 wrote: Yep, reporters don't do surveying numbers well
When Dr.Senna of LSU (now NGS) installed our local CORS station, a very good reporter from the New Orleans paper did a piece. He contacted me about the impact for local surveying.
I explained to him the benefits of attaining Lat/Long and elevations in a timely matter and the cm accuracy for elevations and better for Lat/Long.
Well, he quoted me that surveyors could attain instantly an accuracy of 1 mm for elevations. I kept a low profile for awhile from embarrassment.
pretty much a synopsis of the metrication efforts of FWHA and the various DOT's of the nation.....
In a different lifetime me and my Pa did a lot of clay target shooting and one event I participated in at about 16 years of age was the inaugural regional schoolboy champs. Being inaugural and relatively interesting (i.e. different from rugby and soccer) a reporter from the local rag showed up at the height of competition and sailed up to the traps (3 of them) watching in awe as spotty little pencil-necks called "pull" and fired shotguns and smashed clays left, right and center. Then he asked "are those boys shooting blanks". Even at that age I thought "what a kn.b" (rhymes with job). That was over 30 years ago - still remember it.
