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Thought? Is this it?


foxtrot_xray
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Hey guys, have a little puzzler - only because of the lack of information.

 

V 147 ECC. It's sister to V 147

 

I found the ECC at coordinates 39.232247, -77.431435. These coordinates are about 51 feet south of the ADJUSTED coordinates posted on the sheet.

 

The stations description has no helpful information, of course I scoured the area indicated by the adjusted coords, and there was no disturbance in the ground, no indication at all. The iron rod I found was about 1 inch below ground level.

 

Once the sun comes out, I'll be going back to get measurements from the roads/intersection and V 147 station.

 

Thoughts?

 

Cheers all.

-Mike.

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I am in the general area and have the capability to get a 1 cm precision GPS position that could possibly be used to verify or qualify what you found.

 

It seems unusual to me that a rod or rebar type monument would be accepted by NGS, but you never know.

 

Email me if you are interested in positional verification. This would be on a hobby basis since I am not a licensed surveyor in MD.

 

51 feet would not necessarily be out of limits for error on a conventional recreation grade GPS unit, although with WAAS and the right datum and open sky one would expect it to be within 20 feet.

 

jwahl@qubicle.com

 

- jlw

Edited by jwahl
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It seems unusual to me that a rod or rebar type monument would be accepted by NGS, but you never know.

 

 

There are maybe a hundred 'tagged rebar' type monuments along at least two freeways in Arizona.

The US 60 (Superstition Freeway) in Mesa out to Apache Junction, and I-10 near it's intersection with I-8 and eastward.

Obviously a lot of money was spent on some very temporary marks!

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Hey guys, thanks for the responses. I did a little research, and it does seem that this group put down these marks for a project in the 1990's, as I recovered some easy ones set by them at the same time. They put in about 62 marks, of which I about 4 are iron rod ECC stations (marked as 'bolts' on the datasheets). The descriptions are lackluster, but there's no mention any sleeve or access lid.

 

The other three, one someone here tried unsuccessfully to find, the other two are a bit from me, but next weekend - depending on weather - I may check them out. If they look similar or not, that'll be a clue.

 

-Mike

Edited by foxtrot_xray
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There are a lot of iron rods in the world, more for property corners than for geodetic marks, although I have found a few that are in the NGS data base.

 

I wouldn't trust an uncapped one without good agreement to some sort of check measurement.

 

Since V 147 has only scaled coordinates, you don't have much to measure horizontally from; all you have are adjusted coordinates for the ECC. A handheld reading 51 feet off does not give me any confidence. I'd go back another day and take a 15-minute average waypoint, if your unit offers that capability.

 

Does your candidate for V 147 ECC JV7251 appear to be 6.0 feet lower than V 147 JV3864 as reported on the NGS data sheets?

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Does your candidate for V 147 ECC JV7251 appear to be 6.0 feet lower than V 147 JV3864 as reported on the NGS data sheets?

Ah! Good thinking! I didn't think to check that - I was surprised that the ECC didn't have a PidBox for V 147, I didn't think of checking the heights. *From memory*, I'd say yes, it was 6 feet under. However, I'm pretty sure I will go back this weekend, and when I do I'll double-check that.

 

My GPS (PN-40! :D) does have an averaging feature, and those coordinates were averaged for about 3 minutes, reporting an average error of +- 8ft. Which is why I thought it strange that it was about 50 feet off of where it was reported to be.

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If I had found that rod, I would likely post a note rather than a found-it.

 

I might've logged found-it if it matched distance measurements and bearings but in this case, there are none so it's just an unmarked rod in the ground in the vicinity of those coordinates.

 

For what you did find, I would also give a couple of distance and bearing information sets like from one of those powerpoles or from the centerline of one of those roads.

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If I had found that rod, I would likely post a note rather than a found-it.

Great point, thanks. I changed my log over. :D If it does turn out to be the station, I will do some measurements from the roads and such and give a better description if/when it's logged.

Edited by foxtrot_xray
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