Jump to content
Sign in to follow this  
Followers 2
southpawaz

A tower question

Recommended Posts

I'm pretty new to benchmarking and came across a new to me situation this week. I visited Mount Ord here in Arizona, which has two PIDs located on the summit: DU2039 for the fire lookout tower, and DU2040 for a benchmark. At the time I went I wasn't clear on why the tower would be a benchmark, but reread the FAQ and now see how intersection stations used so that part makes sense now.

 

The last recovery note on DU2039 was from 1981, and the tower looked to be of much newer construction than one built prior to the first record from 1946, and sure enough, when I got home, a quick google search revealed that the present tower was constructed in 1983 (and apparently DU2040 was destroyed in the process).

 

I'm curious about what the best way to log this one is; I logged a note indicating the construction and date of the new tower. For surveying purposes would the new tower be equivalent to the old one?

Share this post


Link to post

If the old tower is gone, the mark is considered destroyed. I had that happen to me with JW1315

I claimed a find on the fire tower and put a geocache on it. Later I found out that the original firetower was torn down and a new one built.

Share this post


Link to post
The last recovery note on DU2039 was from 1981, and the tower looked to be of much newer construction than one built prior to the first record from 1946, and sure enough, when I got home, a quick google search revealed that the present tower was constructed in 1983 (and apparently DU2040 was destroyed in the process).

 

I'm curious about what the best way to log this one is; I logged a note indicating the construction and date of the new tower. For surveying purposes would the new tower be equivalent to the old one?

If surveyors are even using intersection stations any more, no, the new tower would not be equivalent; it's unlikely to be precisely the same height, and according to the reports on that specific tower, even the location isn't the same.

 

When you ask about the best way to log this one, do you mean on Geocaching.com or with the NGS? The note you have put on the Gc.com page for DU2039 is good. You might want to edit it to add that the building of a new tower means that DU2039 is destroyed, but don't get your hopes up that other geocachers will pay attention to that. I was just on the page for an actual benchmark disk the other day, and people are still logging it as found even though multiple people have pointed out that it clearly says "RESET," it's 500 feet across and down the street from the location of the mark that bore that PID, and the original was at a high school that has been replaced by shops and apartments! So even when the situation is laid out clearly, some people don't pay attention. End of rant...

 

If your question was about logging it with the NGS, that's trickier. NGS will require proof of the station's destruction. In the case of HT2630, I was able to send them photos taken by a USGS employee of the three towers collapsed partway up. (I.e., the tops of the towers were hanging down next to the still-standing bottom segments.)

 

I was about to suggest that you file a MARK NOT FOUND report on DU2039 and note in your comments that the tower has been replaced, but NGS may not want that. BH forum folks, I know they don't want "found" reports, but what did they say about "not found" reports? If "southpawaz" were to file a not found with comments about the old foundation and the research on the tower's replacement, would that not be useful information for surveyors?

 

Patty

Share this post


Link to post

Adding to Wintertime's excellent response.....

 

I believe there is some value in logging "not found" reports on destroyed towers. It goes toward the history. In your log, it is important to note if the foundations for the tower legs remain. My reasoning is that occasionally there are other marks in the vicinity which used one of the tower legs as a reference. (Ditto for water tanks.)

 

Sometimes, there even is a benchmark located in the foundation, itself, and you might not be aware of this at the time of your visit.

 

Bottom line: It's been pretty well established by NGS and our professional-surveyor members that nobody is using intersection stations, these days. Still, someone reading the data sheets for all marks within a half-mile radius might benefit from your Not Found report, even though the tower is not his/her specific object of interest. This could be especially true in the case of a tower replacement at nearly the same location--as described in the original post.

 

-Paul-

Share this post


Link to post

I'm pretty new to benchmarking and came across a new to me situation this week. I visited Mount Ord here in Arizona, which has two PIDs located on the summit: DU2039 for the fire lookout tower, and DU2040 for a benchmark. At the time I went I wasn't clear on why the tower would be a benchmark, but reread the FAQ and now see how intersection stations used so that part makes sense now.

 

The last recovery note on DU2039 was from 1981, and the tower looked to be of much newer construction than one built prior to the first record from 1946, and sure enough, when I got home, a quick google search revealed that the present tower was constructed in 1983 (and apparently DU2040 was destroyed in the process).

 

I'm curious about what the best way to log this one is; I logged a note indicating the construction and date of the new tower. For surveying purposes would the new tower be equivalent to the old one?

 

Original tower destroyed=benchmark destroyed.

 

Although photos of the old tower being dismantled would be preferable, I'll bet Deb would accept the results (send her the links) of your research as proof enough that it has been destroyed.

 

I'd also be willing to bet that Deb would accept DESTROYED reports on intersection stations from most of the regulars here on just a say-so. It's best when you have photos of the destruction, but how often is that going to happen? Obviously a photo of a GPSr at the co-ordinates, where there is no antenna, water tank, or smokestack would be better than nothing, but many of the locations are not accessible to just anyone. Sometimes all you can say is 'There is NO _______ here!'.

 

I haven't tried it, but it seems the NGS wants to clear out all the missing ones, especially since they are not so useful anyway.

 

Edited to add: For some of the intersection stations, the description will say 'The point sighted on was the light at the top of the tower'. THEORETICALLY, changing the bulb destroys the mark!

Edited by AZcachemeister

Share this post


Link to post

Thanks to all for the very informative replies.

 

One interesting note is that the tower apparently was "destroyed" only for surveying purposes: according to The National Historic Lookout Tower Register website, it was moved to a Museum in nearby Payson, which I haven't yet visited to verify. According to the Museum's site, they have the top portion of the tower.

 

Based on your input, I have changed my geocaching.com log to mark the tower benchmark as destroyed. I hadn't submitted anything to NGS for this one, that's partly why I was asking here. Given your advice, I will go ahead and submit it as destroyed, with the above link.

 

This is fun!

Share this post


Link to post

>THEORETICALLY, changing the bulb destroys the mark!

 

Not really. Small changes might degrade the order of accuracy of the mark, but if you know it moved less than X you can say it is still good to some tolerance. When it has moved enough that no one is interested in it because the accuracy is so poor as to be useless, then it is destroyed.

 

Even if it was first order (rare in triangulation stations), if the light bulb moved less than 2 inches, and the nearest other horizontal control station in your network is 1 mile away, then was known to roughly an inch and now at 3 inches max it still may be good to 1:20,000 which one book I have lists as Secnd Order Class I. I don't recall the current NGS definitions of order.

Share this post


Link to post

I have been to a lot of destroyed fire towers ~50

 

I read the description and if they say they sighted on the center of the roof and the tower is gone or just the roof is gone, I log it as MARK DESTROYED with Groundspeak but haven't bothered with NOAA, surelay a photo of the footings would be what they need as they could check with the state forestry agency to be sure

 

At least one where the tower is gone the description was center of base of tower and I logged that one as FOUND because you could sight halfway between the footings to get center of base

 

Others feel free to disagree

 

A lot of people have been careless with towers including me, and logging any standing tower as the one in the description without checking their GPS to see if it moved, or seeing if the height matches the description. I have even seen somebody log a wood groundhouse as FOUND when the present tower is metal and 100 yards away from the old site

Share this post


Link to post

 

 

Although photos of the old tower being dismantled would be preferable, I'll bet Deb would accept the results (send her the links) of your research as proof enough that it has been destroyed.

 

 

I sent links for a destroyed intersection station once and was requested to not send them.

 

It was a great link to a news story that showed the actual destruction of the mark in question but the request for no links in the future was made clear to me.

Share this post


Link to post

>THEORETICALLY, changing the bulb destroys the mark!

 

Not really. Small changes might degrade the order of accuracy of the mark, but if you know it moved less than X you can say it is still good to some tolerance. When it has moved enough that no one is interested in it because the accuracy is so poor as to be useless, then it is destroyed.

 

Even if it was first order (rare in triangulation stations), if the light bulb moved less than 2 inches, and the nearest other horizontal control station in your network is 1 mile away, then was known to roughly an inch and now at 3 inches max it still may be good to 1:20,000 which one book I have lists as Secnd Order Class I. I don't recall the current NGS definitions of order.

 

Just like bumping a concrete post with a road grader?

Hey, it's only leaning 7 degrees!

 

The point being, if the precision is diluted, it's not the same mark.

Useful, perhaps, but not the same.

Share this post


Link to post

 

 

Although photos of the old tower being dismantled would be preferable, I'll bet Deb would accept the results (send her the links) of your research as proof enough that it has been destroyed.

 

 

I sent links for a destroyed intersection station once and was requested to not send them.

 

It was a great link to a news story that showed the actual destruction of the mark in question but the request for no links in the future was made clear to me.

 

Perhaps the pertinent text should be copied into the EMail to Deb?

Share this post


Link to post

 

Perhaps the pertinent text should be copied into the EMail to Deb?

 

That is probably a good idea. A reference to the web page without turning it into a link may be good also.

That way if someone wanted to it could be easily referred to.

Share this post


Link to post

A few thoughts on various items in this thread:

 

Deb is very busy and doesn't really have time to follow links to research destroyed stations. She also requires first person accounts from what I can gather, so she wants YOUR images of the destroyed station, not a link to a third party video, news article, etc.

 

Deb might take our word for the destruction, as AZ mentioned. One time she actually did that for me when I forgot to send pics with my email. I rectified the error. She did remind me to send pics with future logs however so it isn't something I would want to make a habit of.

 

From what I have seen the light bulbs on top of towers are covered with glass globes. I may be wrong and I am sure even if I am right there are instances where the bare bulb is used, but I always pictured something like this:

810SE.jpg

with a cover over a bulb. That means that changing the bulb, under the globe, will have no effect on the position of the intersection point. Replacing that unit with a newer one might however, especially if it was placed in a different location so the old one could remain in use while the new one was installed.

 

The final word is that Deb is no longer interested in getting recoveries for intersection stations except when they are destroyed.

Share this post


Link to post
Deb is very busy and doesn't really have time to follow links to research destroyed stations. She also requires first person accounts from what I can gather, so she wants YOUR images of the destroyed station, not a link to a third party video, news article, etc.

Although third-party accounts from a reputable source should do the job, too. I got an intersection declared destroyed by sending her photos taken by the USGS.

 

The final word is that Deb is no longer interested in getting recoveries for intersection stations except when they are destroyed.

We know that she doesn't want "found" reports, but as mentioned earlier, are we sure that she never wants "no found" reports that provide significant information about the station's fate? When someone knows that a station has been destroyed, but doesn't have evidence that meets NGS standards to have the station declared destroyed, might it not help surveyors to know what happened to the station? Especially if a replacement tower, spire, etc. was erected that might be mistaken for the original station by someone who didn't know its history?

 

Patty

Share this post


Link to post

We know that she doesn't want "found" reports, but as mentioned earlier, are we sure that she never wants "no found" reports that provide significant information about the station's fate? When someone knows that a station has been destroyed, but doesn't have evidence that meets NGS standards to have the station declared destroyed, might it not help surveyors to know what happened to the station? Especially if a replacement tower, spire, etc. was erected that might be mistaken for the original station by someone who didn't know its history?

 

Patty

My reading of her statement is that the NGS is not interested in intersection stations for any surveying purpose and they are left in the database only for historic reasons. In other words surveyors don't use them and don't care about what happened to them. Therefore, the only interesting recovery is a DESTROYED status supported by hard first person data (photos), so she can take that particular record out of the active portion of the database (i.e. clean up the database).

 

If anyone has a different interpretation of the situation, please chime in.

Edited by Papa-Bear-NYC

Share this post


Link to post

We know that she doesn't want "found" reports, but as mentioned earlier, are we sure that she never wants "no found" reports that provide significant information about the station's fate? When someone knows that a station has been destroyed, but doesn't have evidence that meets NGS standards to have the station declared destroyed, might it not help surveyors to know what happened to the station? Especially if a replacement tower, spire, etc. was erected that might be mistaken for the original station by someone who didn't know its history?

 

Patty

My reading of her statement is that the NGS is not interested in intersection stations for any surveying purpose and they are left in the database only for historic reasons. In other words surveyors don't use them and don't care about what happened to them. Therefore, the only interesting recovery is a DESTROYED status supported by hard first person data (photos), so she can take that particular record out of the active portion of the database (i.e. clean up the database).

 

If anyone has a different interpretation of the situation, please chime in.

 

Well, I guess that may actually be the case, but...

 

What are the chances that someone who knows the old antenna for radio station KRAP is/was an intersection station will be on hand to photograph it's destruction?

 

I don't see the database getting cleaned-up very fast with those restrictions. But it IS their database, so I will continue to not send any reports for intersection stations (unless I happen to see one being destroyed!).

Share this post


Link to post

What are the chances that someone who knows the old antenna for radio station KRAP is/was an intersection station will be on hand to photograph it's destruction?

 

I don't see the database getting cleaned-up very fast with those restrictions. But it IS their database, so I will continue to not send any reports for intersection stations (unless I happen to see one being destroyed!).

It's not quite that stringent. Although I know someone here posted a video of a radio tower crashing down (Anyone remember who/what that was?)

 

I usually send a photo of where it was, particularly if the footings are there, and usually with a GPS pointing at the footings and saying 5 feet to the station (or something like that). Like this one LX4281 - ANTHONYS NOSE BEACON

I sent an email to Deb with this picture And it got classified as destroyed in about two months:

 

d92c4401-a1e6-40bb-be77-bbced59704e8.jpg

(That's one of the surviving footings in the picture)

 

As opposed to surveyors who (in their professional capacity) don't care about intersection stations, I like them a lot, particularly historic ones, like the High Bridge Water Tower in Manhattan (KU3973 - HIGHBRIDGE 1898), used in the 1909 triangulation of NYC. Who wouldn't like this baby. They'll destroy this one over my dead body:

 

4393c348-e81e-43af-9485-e3e87c520a7f.jpg

Edited by Papa-Bear-NYC

Share this post


Link to post
It's not quite that stringent. Although I know someone here posted a video of a radio tower crashing down (Anyone remember who/what that was?)

I think Larry posted the original report when the KFI tower was knocked down by a plane in 2004. A couple of month ago, I posted a link to a video of the replacement tower project not going so well. The person who took that video is also a geocacher and joined the conversation. Ah, here we go; he's K6RIX: http://www.k6rix.com/. No word on another attempt to replace the tower. I wonder how much of a problem the backup transmitting facility really is for KFI. They still come in solidly in the Bay Area at night.

 

Patty

Share this post


Link to post

Papa-Bear...I am glad someone else heard the same message I did about intersection stations!

 

I don't want to come down as the heavy in all this though, it was just how I interpreted Deb's request regarding intersection stations--they are no longer used and while she will be happy to remove destroyed ones from the database she doesn't need information about existing ones.

 

You don't have to send evidence of the actual destruction, just the lack of a station. Unlike disks and other "set" marks, it is usually pretty obvious when a tower/smokestack/beacon goes missing.

 

It is really very easy to get a truly destroyed intersection station listed as such--just take a pic of your GPSr in GOTO mode with the arrow visible and pointing to the non-existent station. Then take a farther pic showing that there is nothing there. Deb will mark it destroyed based on that evidence. See KV3608 for an example.

 

Also, there are sometimes enough differences between old and new antennas that you can confirm that they are gone. Take KV3612 for instance. On the ASR database it appears to have been constructed in 2005 and it is at a slightly different location than the described antenna (most likely so the new one could be build beside the old one without interrupting service), but not far enough different for me to feel confident that it was new. However, it is a triangular structure as opposed to the square one described. That single piece of evidence led me to report it as destroyed. My report was accepted.

Share this post


Link to post

Can someone tell me (in simple terms) why intersection points aren't used in surveying (and are therefore not necessary to report)?

 

Thanks.

Share this post


Link to post

Can someone tell me (in simple terms) why intersection points aren't used in surveying (and are therefore not necessary to report)?

 

Thanks.

Traditionally. intersection stations were used to provide an azimuth when a surveyor was setting up over a mark. The surveyor would know exactly where he/she was but not have a super accurate way of knowing which way is which. A compass is not very accurate for that. By sighting on an intersection station, an exactly known azimuth was established, so that was the missing piece of information.

 

Now-a-days a surveyor will use high grade GPS, so he/she can use the GPS to establish the location and use a nearby point with the GPS to get the azimuth. I've been told (thanks Holtie) that when new marks are set, they are typically done in pairs, so there will always be a nearby point to establish an azimuth. And even if there isn't a nearby point already there, the surveyor can establish a temporary point to use for finding the azimuth. GPS, in affect, allows any point to serve as an azimuth mark.

 

Real surveyors are asked to chime in here and elaborate on this (keep me honest).

 

Incidently, High Bridge Tower, which I mentioned in my recent post, was not actually an intersection station. Surveyors went up into the tower and "occupied the station" as the jargon goes and took sightings on other marks. So it was actually a triangulation station in the fullest sense. And it's beautiful (did I mention that)! OTOH, church steeples and radio towers can't be "occupied" (unless the steeple has a belfry with windows) so they are true intersection stations. You can think of it as any station that is sighted from other stations, but which is not used to sight back to those other stations, is an intersection station.

Edited by Papa-Bear-NYC

Share this post


Link to post

Intersection stations were used by surveyors to determine the horizontal position of a particular point on the earth's surface through a process called resection. Global Positioning Systems have made that a lot easier.

 

Intersection stations are objects with a known horizontal (Lat/Long) position. From a point of unknown position, a surveyor would set up and sight at least three intersection stations. By measuring the angles between the known stations, the unknown position, where the surveyor was set up, could be mathmatically calculated. Once the horizontal (Lat/Long) position was known for the set up point, an azimuth between that point and one of the other known points could also be calculated, along with "true north" calculated for the immediate local area.

 

Hope this helps.

 

- Kewaneh

Share this post


Link to post

My $.03 (inflation!) is this - I reported several intersections as destroyed, and they got taken off, no other word from Deb. I never heard this 'they don't want to hear about intersection stations', but I took a hint from ya'll and have stopped reporting them..

 

My question is this - why aren't they just taken out of the database then? (Or, moved to their own database for reference?) It wouldn't be that hard - in theory.. right?

Share this post


Link to post

You don't have to send evidence of the actual destruction, just the lack of a station. Unlike disks and other "set" marks, it is usually pretty obvious when a tower/smokestack/beacon goes missing.

 

It is really very easy to get a truly destroyed intersection station listed as such--just take a pic of your GPSr in GOTO mode with the arrow visible and pointing to the non-existent station. Then take a farther pic showing that there is nothing there. Deb will mark it destroyed based on that evidence. See KV3608 for an example.

 

Also, there are sometimes enough differences between old and new antennas that you can confirm that they are gone. Take KV3612 for instance. On the ASR database it appears to have been constructed in 2005 and it is at a slightly different location than the described antenna (most likely so the new one could be build beside the old one without interrupting service), but not far enough different for me to feel confident that it was new. However, it is a triangular structure as opposed to the square one described. That single piece of evidence led me to report it as destroyed. My report was accepted.

 

Now that is what I wanted to hear! A 'qualified observer' says there is no such object here, and it can be removed.

Triangular VS. Square? Now that is what I call attention to details!

 

My $.03 (inflation!) is this - I reported several intersections as destroyed, and they got taken off, no other word from Deb. I never heard this 'they don't want to hear about intersection stations', but I took a hint from ya'll and have stopped reporting them..

 

My question is this - why aren't they just taken out of the database then? (Or, moved to their own database for reference?) It wouldn't be that hard - in theory.. right?

 

If it's still there, and a surveyor wants to use it for some reason...they can. As well, there is the possibility that the description and ties may help locate a 'lost' 'set' mark.

Share this post


Link to post

I just wanted to update everyone who contributed to this thread as to the outcome regarding DU2039, the tower that raised my initial question. It has been removed from the database:

 

>DU2039 MOUNT ORD LOOKOUT TOWER 33 54 17.8/111 24 32.4 3 X

>DU2039 MOUNT ORD LOOKOUT TOWER 33 54 17.8/111 24 32.4 3 NN

(X = Surface Mark Reported Destroyed )

 

Here is the text of the email I sent to Deb (edited to make the link clickable):

 

I attempted to locate this benchmark (Mount Ord Lookout Tower) last week. It was a fire lookout tower, which has been replaced since the last recovery note in 1981. An item referencing the tower's replacement in 1983 was found at The National Historic Lookout Tower Register website.

 

It was suggested to me on the geocaching.com forums regarding benchmarks that I go ahead and submit this information to you for your consideration. If you would like additional evidence I will see what I can come up with the next time I am in that area.

Edited by southpawaz

Share this post


Link to post

Too bad it was destroyed, but it's good to know that you were able to get it declared as such.

Now I feel guilty for all the missing antennae and water tanks I didn't report! :P

Share this post


Link to post

 

Also, there are sometimes enough differences between old and new antennas that you can confirm that they are gone. Take KV3612 for instance. On the ASR database it appears to have been constructed in 2005 and it is at a slightly different location than the described antenna (most likely so the new one could be build beside the old one without interrupting service), but not far enough different for me to feel confident that it was new. However, it is a triangular structure as opposed to the square one described. That single piece of evidence led me to report it as destroyed. My report was accepted.

 

I have had a similar one destroyed, but the differences were a bit greater than this. QM0586 has been removed. There IS a tower registered to the state police, approximately 30-40 feet from the described location, but the coordinates are off, and it's a much newer, self-supporting galvanized (not painted) tower.

 

Now we're getting away from towers, but it's a similar situation, where careful observation and a bit of investigation can be useful. Had I just been a "casual" benchmarker, I probably would have even logged a find (here on GC) on the outer Marquette Harbor breakwall light. Instead, I logged it as destroyed, and Deb accepted my destroyed report.

 

The description for RK0483 is pretty slim, and this light has been here as long as I've been in town--nearly 20 years. However, I was also looking for RK0695, which is described as having the same location. Both are horizontally adjusted marks. The description for the second station provides more detail on the first. The present structure is clearly not what was described in 1981. I emailed a local maritime historian, who confirmed that the light structure was replaced in the early 1980s.

Edited by andylphoto

Share this post


Link to post

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
Sign in to follow this  
Followers 2

×
×
  • Create New...