Cryptic Compass Reference

[VT ARL 784]

The following is an example excerpted from Benchmark PG2640, in (er, not in) Middlebury, Vermont. I've seen this type of directional reference before, but I don't know enough about -- I assume (there's a lot I don't know enough about) -- compass reading:

 

Disk is 29' N15E pole; 35' N62W manhole; 54' N77W centerline of road.

 

Does it mean , ... oh bother, I just can't get my head around it. Any help out there?

 

Thanks

 

(I think I found where the bm was, but it looks like someone's dug it out. So I dug down another foot, but still didn't find anything)

[+TeacherMatt]

I've done a few benchmarks in VA, and have not seen this style of reference to a witness mark. I would guess it means from the pole, you will find the mark 29 feet away at a bearing of 15° N of E. In other words it is 75° on a 360° compass (E is 90° so 15° back towards N would be 90°-15°=75°)

 

I may be way off, but that would be my guess.

 

If you haven't done so, you might post in the BenchMark section of the forums. Those folks are very helpful.

 

Good luck.

 

TeacherMatt

Edited April 9, 2004 by TeacherMatt

[dsandbro]

That format is sometimes used in surveying and engineering.

 

TeacherMatt got it right.

[VT ARL 784]

THanks! So that means: N62W is 60° N of W, i.e. 270+62, =332° ??

 

Problem is, that puts the everything in the wrong direction, in relation to the witiness post, general north, and road. But since I didn't find it . . .

 

I was pretty sure it was something used by surveyors, and I will also post in Benchmark hunting too.

 

Thanks for the feedback.

[+wolf452]

The cryptic is known as a bearing. N15°E is not 15° north of east, it is 15° east of north. same with N62°W, 62° west of north. Now the bearing can be two directions. It can be (but isn't) from the pole it is from the benchmark.

From which a pole is 29' bearing North 15° East. From which a manhole is 35' bearing North 62° West. You will need to reverse these bearings. Oh boy, here we go........ from the pole SOUTH 15° WEST, from the manhole SOUTH 62° EAST, from the centerline of the road SOUTH 77° EAST. This means you should be east of the road, east of the manhole and west of the pole. Better?

[+WVDan]

Confusing, but Wolf452 is correct. I deal with this all the time when I have to draw property plots. Just be happy you don't have to convert the distance from rails, poles, chains or rods. It's not hard to do, but time consuming.

[VT ARL 784]

Ah, yes WOLF452. That does put me on the correct side of things. So they use this combo of 3 factors when they could just say "on a bearing of 62° from BM"? Clarification, I suppose. "Eschew Obfuscation."

 

WVDan: have I got a site for you! (It prints out at about 7 pages, if I recall correctly.) It's from the Vermont Center for Geographic Information, (vcgi.org), and it lists the formulas to convert everything to and from anything (except grains-of-sand, which was the one thing my friend wanted to convert her road mileage to...).

Go directly to the list (no pop-ups/programs to install/etc) at Measurement Unit Conversion Table

 

Or VCGI Home; select Technical Resources Tab, then Tools Options.

 

BTW: The Data Warehouse Tab: Theme Index provides VT downloadable GIS data; and links to Agency of Transportation will lead to VOLGIS, where NGS and VT Benchmarks are retrievable.

 

Thanks to each who contributed to expanding me knowledge in regards to those cryptic crosshares.

 

Keep countin'

[+wvcoalcat]

Bearing circle is 360 degrees broken down into four quadrants with 90 degrees in each quadrant (NE, SE,SW,NW) Azimuth circle is 360 degrees

Simple conversion bearings to azimuths

NE = azimuth

SE = bearing subtracted from 180 (S60E = 180-60= 120 az)

SW = bearing + 180 (S60W= 180+60= 240 az)

NW = bearing subracted from 360 (N60W = 360-60= 300 az)

Hope this helps