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Benchmark Removal


Team ARK-ville

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Just curious if anyone knows the procedure when a benchmark is located in a bridge abutment and the bridge is scheduled to be torn down?

 

I located BM NA0265 yesterday because I knew that the bridge it is on will be torn down in the near future to make way for a new bridge which is being erected next to the present one.

 

The BM is in poor condition and the concrete it is set in is cracking and also very poor. I noticed some numbers that were etched in the concrete next to the BM, they are 243.816. Do these have any significance to the BM?

 

Would this had to have been reported to NGS before the bridge is removed? Possibly those etched numbers have some relation to removing the BM? Would the BM be reset in the new bridge??

 

Check my log for this BM and pictures uploaded for more details.

 

Just curious what happens in a case like this. Any ideas? Thanks.

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That depends on who removes the bridge and if they notice that the mark is there and choose to report its demise.

I have a similar situation nearby and am trying to work with state DOT officials to make sure the removed marks get sent in as destroyed so they do not clutter the NGS database with "not found" entries when they do not exist. The only real time to catch this sort of thing is during the demolition of the station. I would suggest you contact the bridge builders and see what their plans are. Maybe they would let you knock the mark off and you could submit it to NGS (by SUBMIT, I mean submit pictures of the destroyed mark. The NGS is not interested in receiving the disks back).

 

The numbers are the elevation, in meters. The datasheet has:

 

NAVD 88 - 243.820 (meters) 799.93 (feet) ADJUSTED

 

The new bridge may have a mark set in it, although that is rare now. The original mark will be either accidentally put in a dump truck by an unsuspecting demolition worker who did not know it existed, or discarded or kept by a bridge engineer or construction worker as a souvenir.

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Arkville,

 

If you think this BM is soon to be destroyed due to the demolition of this bridge, the procedure to use, should you want to make someone who has the official capacity to keep an eye on it would be to contact the State Geodetic Advisor for the State in Question. Anyone can do this in any State By the way, and the links to do so are on the NGS Home page. Since this station is in the State of New York, and New York has no assigned Geodetic Advisor, The procedure is to contact:

 

Mr. Gilbert Mitchell

National Geodetic Survey, N/NGS1

Telephone: 301-713-3228

 

gilbert.mitchell@noaa.gov

 

You are under no obligation to contact him, but since you asked, that would be what one could do, if they were to choose to do so.

 

He will know how to handle this and make what ever choices which will need made regarding the future loss of this station.

 

That is the procedure. Should he not be informed, the Station may wind up as rubble and lost forever. Then the next time someone searches for it and does not find it, they could enter a change in status for this station in the database from a Good to a Not Found. It would then become a Not Found in the NGS Database until the end of time.

 

The Numbers as Matt pointed out were at one time the elevation for the station. The practice of doing this is no longer in effect and all Elevations stamped or etched into surfaces near BM's are considered to be in error. The methods for deriving accurate elevations did change and it caused all the old numbers to become inaccurate. Currently the only accurate method and accepted practice of obtaining elevation data is through a station's datasheet.

 

Good luck Hunting!

 

Rob

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An odd situation here is that the NMHD (to be renamed NMDOT soon) is destroying/rebuilding a bridge over the highway. I asked the engineers doing the deconstruction/construction what will happen to the nearby station. They're restationing the mark on the other side of the new bridge, using the current mark/concrete pillar. However, this destroys the positioning for NGS, so...

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Arkville,

 

If you think this BM is soon to be destroyed due to the demolition of this bridge, the procedure to use, should you want to make someone who has the official capacity to keep an eye on it would be to contact the State Geodetic Advisor for the State in Question. Anyone can do this in any State By the way, and the links to do so are on the NGS Home page. Since this station is in the State of New York, and New York has no assigned Geodetic Advisor, The procedure is to contact:

 

Mr. Gilbert Mitchell

National Geodetic Survey, N/NGS1

Telephone: 301-713-3228

 

gilbert.mitchell@noaa.gov

 

Thanks Rob,

 

I have sent off an email to Mr. Mitchell as you suggested and also attached the photo's I took. If he replies I will let you and the forum know his response.

 

Roger

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Arkville,

 

If you think this BM is soon to be destroyed due to the demolition of this bridge, the procedure to use, should you want to make someone who has the official capacity to keep an eye on it would be to contact the State Geodetic Advisor for the State in Question. Anyone can do this in any State By the way, and the links to do so are on the NGS Home page.  Since this station is in the State of New York, and New York has no assigned Geodetic Advisor, The procedure is to contact:

 

Mr. Gilbert Mitchell

National Geodetic Survey, N/NGS1

Telephone: 301-713-3228

 

gilbert.mitchell@noaa.gov

 

Thanks Rob,

 

I have sent off an email to Mr. Mitchell as you suggested and also attached the photo's I took. If he replies I will let you and the forum know his response.

 

Roger

Just a note to say, I have not received any communication from Mr. Mitchell. Have no idea if he has read the email or not or if he intendes to respond.

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Arkville,

 

In this day and age, it seems we don't always get a response if we do not implicitly ask to receive one.

 

If you like, write to Gilbert a second time and ask him if he received you previous email, and offer to see if there is something that you can do to help. He will likely answer you then :-)

 

Rob

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Could be he has more important fires to put out?

 

It appears this guys job may be personel related etc. I may be wrong but he is likely a humans resources type person. He may have just forwarded your email to someone like Deb etc.

 

In other words, he may have more important duties.

Edited by Z15
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