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cesariojpn

I think the markers are in a truely inaccesable location.....

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Am I right in reasoning these two markers are in holes drilled into busy roadways? The datasheet cords appear to be off vs. the descriptions.

 

TU0915 I think is in the middle of a highway here vs. in a field (I think the cords are pointing to a rockpile in the middle of the field here).

 

TU0857 appears to be in the middle of an intersection instead of somewhere here.

 

Both of these marks have scaled coordinates (which can be off by 600+ feet from the actual location). If/When you do find these marks, make sure to take gps readings and submit these new coordinates as Handheld 2 numbers in your logs. This will make the coordinates accurate to 15-30 feet, which is a lot better than 600+ feet.

 

Here is the explanation of scaled vs adjusted coordinates on datasheets:

 

What is the difference between "Location Adjusted" and "Location Scaled?"

 

Simply put, "location adjusted" means that the published coordinates are very accurate, and "location scaled" means that the published coordinates are not very accurate. The published positions for benchmarks with adjusted horizontal coordinates were computed using advanced surveying techniques and are far more accurate than even the finest handheld GPSr can get. The position of a benchmark with "scaled" coordinates was derived by a human in an office by estimating the location of the mark on a topographic map with a scale (ruler). As such, they can be off by 600 feet or more from the actual position though deviations in the 100 - 150 foot range are more common. Your handheld GPS may be very helpful in finding benchmarks with adjusted horizontal coordinates, but can be nearly useless for finding benchmarks with scaled horizontal coordinates. The good news is that only vertical control points have scaled horizontal coordinates. Trying to use your GPS "GOTO" function to find a benchmark with scaled horizontal coordinates will usually lead to frustration and failure.

 

How can I determine whether a particular mark is "Location Adjusted" or "Location Scaled?"

 

On a Geocaching benchmark datasheet, the second line under the coordinates will say either "location is ADJUSTED" or "location is SCALED".

On the 9th line of an NGS benchmark datasheet, to the right of the latitude and longitude coordinates, will be either the word ADJUSTED or the word SCALED. (Don't confuse this with the next line down, which tells whether the vertical elevation is adjusted or scaled.)

 

I have copied/compiled a lot of info from these forums and posted it in a local geocaching forum, that explains adjusted, scaled, and Handheld 2 coordinate numbers you may encounter on datasheets. It also explains the difference between the horizontal and vertical datum on the datasheets and not to get them confused. It is at the link below:

 

http://www.nelageo.net/index.php?option=com_kunena&func=view&catid=13&id=10956&Itemid=54

 

TU0915 is on the headwall, of the culvert. If this is still the same road and culvert, the disk is most likely near the edge of the headwall, which would not be in the road but to the side of it. Probably something similar to this:

 

95708e68-4c8f-424d-9c6b-0f53b5f5af52.jpg

 

98d89329-1b03-47e9-be57-a45dd1bfe4a6.jpg

 

TU0915_MARKER: DV = VERTICAL CONTROL DISK

TU0915_SETTING: 32 = SET IN A RETAINING WALL OR CONCRETE LEDGE

TU0915_SP_SET: CULVERT HEADWALL ON LAVA FLOW

TU0915_STAMPING: B 24 1979

TU0915_MARK LOGO: NGS

TU0915_MAGNETIC: N = NO MAGNETIC MATERIAL

TU0915_STABILITY: C = MAY HOLD, BUT OF TYPE COMMONLY SUBJECT TO

TU0915+STABILITY: SURFACE MOTION

TU0915

TU0915 HISTORY - Date Condition Report By

TU0915 HISTORY - 1979 MONUMENTED NGS

TU0915

TU0915 STATION DESCRIPTION

TU0915

TU0915'DESCRIBED BY NATIONAL GEODETIC SURVEY 1979 (WVM)

TU0915'1.6 MILES NORTH ALONG STATE HIGHWAY 37 FROM THE JUNCTION OF STATE

TU0915'HIGHWAY 400 IN PUKALANI, SET IN TOP CENTER OF THE EAST CONCRETE

TU0915'HEADWALL OF A BOX CULVERT, 27 FEET EAST OF THE CENTER OF THE HIGHWAY.

 

TU0857_MARKER: DV = VERTICAL CONTROL DISK

TU0857_SETTING: 32 = SET IN A RETAINING WALL OR CONCRETE LEDGE

TU0857_SP_SET: HEADWALL

TU0857_STAMPING: H 22 1979

TU0857_MARK LOGO: NGS

TU0857_MAGNETIC: N = NO MAGNETIC MATERIAL

TU0857_STABILITY: C = MAY HOLD, BUT OF TYPE COMMONLY SUBJECT TO

TU0857+STABILITY: SURFACE MOTION

TU0857

TU0857 HISTORY - Date Condition Report By

TU0857 HISTORY - 1979 MONUMENTED NGS

TU0857

TU0857 STATION DESCRIPTION

TU0857

TU0857'DESCRIBED BY NATIONAL GEODETIC SURVEY 1979 (WVM)

TU0857'0.8 MILE NORTH OF PUUNENE, AT THE JUNCTION OF STATE HIGHWAYS 35 AND

TU0857'STATE HIGHWAY 38, 38 FEET WEST OF THE CENTER OF STATE HIGHWAY 35, 21

TU0857'FEET SOUTHWEST OF MILE POST 1, 100 FEET NORTH OF THE CENTER OF STATE

TU0857'HIGHWAY 38, AND 25 FEET NORTHEAST OF UTILITY POLE NUMBER 147T.

Edited by LSUFan

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As LSUFAN said, don't trust the coordinates other than to get you close to the mark. Go by the description, and both descriptions have the marks on a headwall of a culvert. Culverts can be anything from a tiny trickle under the roadway up to, but not including, a true bridge. The headwall is parallel to the roadway.

 

Also notable is that both marks were established in 1979, which is eons ago in terms of roadways, and I am almost certain that 307 was widened since then. In reference to TU0915, it looks like they may have kept the original roadway and added the northbound lane (westbound? I am not sure since the road goes southeast to northwest). If you head a bit southeast of the point where your maps shows the mark you will see headwalls, and they could certainly be the ones you are looking for. Their choice of directions is probably based on road direction, so the east headwall would be based on a road direction of north, and would be the one to the northeast side of the road. However, if 307 was widened by adding a new roadway to the north, the headwall you want is the one north of the southern lanes of the highway.

 

TU0857 may also be there but I would bet that the intersection was rebuilt, and if that is the case chances are they rebuilt the culverts, as it is harder to keep them in place in that sort of situation. Your problem here will be measuring anything without getting run over. On busy roadways I tend to pace the distance instead of trying to measure it. It isn't precise but it much faster.

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TU0915 — The description points to the intersection of old and new hwy 37. (Rt 400 appears on the topo map; it's now Makawao Ave.) Use these coordinates: 20.84955, -156.34977. The Bird's Eye view on Bing Maps looks to me like a conventional round culvert, with or without headwall, on the south side of the intersection, but a likely box culvert on the north side. The intersection and the waterworks look to me much newer than 1979, so you may be out of luck on this one.

The description is your friend. It's very often more helpful than scaled coordinates, which can be way off ... or spot-on; you never know.

-ArtMan-

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TU0915 — The description points to the intersection of old and new hwy 37. (Rt 400 appears on the topo map; it's now Makawao Ave.)

 

Minor question, but why does your link point to a spot that according to the Topo maps is the location of a BM (BM 188(3? 8?) near the intersect of Holopuni & Pulehu??

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TU0915 — The description points to the intersection of old and new hwy 37. (Rt 400 appears on the topo map; it's now Makawao Ave.) Use these coordinates: 20.84955, -156.34977. The Bird's Eye view on Bing Maps looks to me like a conventional round culvert, with or without headwall, on the south side of the intersection, but a likely box culvert on the north side. The intersection and the waterworks look to me much newer than 1979, so you may be out of luck on this one.

The description is your friend. It's very often more helpful than scaled coordinates, which can be way off ... or spot-on; you never know.

-ArtMan-

 

Was going to recommend looking in that same area, even without seeing your post. I used the Benchmark viewer website and saw the ditch on it North of the mark's position. From the right spot, zooming in with Google Street View seems to show some sort of concrete structure off the road, as well as something that looks to me like a building, possibly with a bridge going to it from land.

 

http://maps.google.com/maps?q=20.84955,+-156.34977&hl=en&ll=20.849499,-156.349594&spn=0.000645,0.001321&sll=20.847222,-156.351389&sspn=0.010247,0.021136&t=h&z=20&layer=c&cbll=20.849527,-156.349675&panoid=cJx5hlJJw5k69JNfZ6qq6w&cbp=12,31.53,,0,2.3

 

And, from my early days at Benchmark hunting, here's another example of a culvert mark that didn't have very accurate coordinates:

ac3861a5-cb1d-49d2-9df3-52d4358c7ebd.jpg

 

Trying to get to those coordinates would result in very wet feet. (Among other things.) :)

Edited by EdrickV

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TU0915 — The description points to the intersection of old and new hwy 37. (Rt 400 appears on the topo map; it's now Makawao Ave.)

 

Minor question, but why does your link point to a spot that according to the Topo maps is the location of a BM (BM 188(3? 8?) near the intersect of Holopuni & Pulehu??

 

The benchmark there would appear on USGS topographic maps, and may or may not be related to the NGS mark. Could be the position is wrong, or it could be an entirely different mark. USGS marks and Army Corps of Engineers marks aren't always bluebooked for the NGS and there are other local agencies that make their own benchmarks. The number would indicate the elevation at the mark. It is possible that mark may not exist anymore too. There are even NGS marks that may exist but wouldn't come up in a normal search because they got flagged as destroyed, or are non-publishable due to lack of information.

Edited by EdrickV

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TU0915 — The description points to the intersection of old and new hwy 37. (Rt 400 appears on the topo map; it's now Makawao Ave.)

Minor question, but why does your link point to a spot that according to the Topo maps is the location of a BM (BM 188(3? 8?) near the intersect of Holopuni & Pulehu??

Doesn't point there for me. I entered those coordinates into both Google Maps and Acme Mapper, and in both cases it brought me right to the intersection of new and old highways 37 (Haleakala Hwys).

 

To get those coordinates, I measured the distance from the Description: "1.6 MILES NORTH ALONG STATE HIGHWAY 37 FROM THE JUNCTION OF STATE HIGHWAY 400 IN PUKALANI" (I used the very helpful Distance Measurement Tool from Google Maps; click on the "Maps Lab" link in the left panel for it and other useful add-ons.)

 

I confess I missed the BM marked on the topo map. The elevation, 1124, corresponds to the elevation on the Datasheet, 1123.54, so I'm pretty confident that represents the benchmark we're searching for. I think the position on the topo map is probably fairly reliable in a general way. In this case, along the old highway 37, and definitely not on the north side of the new highway (where I saw a box culvert), as I suggested earlier. From Google aerial view there does not appear any box culvert in the area indicated by the X on the topo map, so I would now think that the mark is probably gone. Maybe worth a look if you're in the area, but I would not be optimistic.

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