Description Conventions

[holograph]

I found a station this weekend that needs an updated description, but I hesitate to submit a recovery to NGS unless I'm sure that I won't do more harm than good.

 

In particular, I found LY0427 this weekend. When it was placed in 1942, there were nothing but trees in all directions, so the best they could do was mark them with blazes and use those as ties. Needless to say, they are very hard to find today.

 

Today at this location, there is now a very obvious power transmission line right of way, and diagonally across the road is a power pole:

 

 

The map shows the road, the pole, and the station location. The high-tension line right of way runs east-west across the road.

 

I have considered just saying "at the northern edge of a power transmission line right of way. Handheld GPSR coordinates ..." That description alone would be helpful, since the scaled coordinates put it south of the right of way, where I wasted a lot of time searching for it.

 

I also paced off the distance from the sole nearby power pole, and could attempt to say something like "approximately 35 feet north of power pole BTE2727WM. Is is correct to state the distance as paced along the length of the road from the power pole? Is it necessary to give a direct straight-line distance (diagonally across the road) from the pole to the station?

 

Is any approximate distance useful at all? As a newbie, I have not yet obtained a wheel or tape that could give an accurate distance, so the best I can do is measure paces.

 

Thanks for your advice.

Edited November 22, 2004 by holograph

[Z15]

This is how I would describe it. The xx are the unknowns you need to furnish.

Opps. just noticed you do not have a tape measure, paces would do then as long as you feel confident in your pacing. I have seen some NGS ones that used paces. fyi-I found a cheap 100 ft carpenters tape measure on sale at Menard's for less then $10, it an open wheel nylon tape suitable for this type of work.

 

Start at a well defined intersection and list the miles and directions to get the vicinity of the mark.

 

Such as,

 

To reach from the intersection of US HWY 69 and Holograph Rd, follow Holograph Rd about 1.5 miles SW to the mark on the right, at the northern edge of a power transmission line right of way. About 0.25 miles NE of the bridge over Mud Creek.

 

The mark is xx feet NNW and across the road from utility pole Number ??, xx feet NW of the c/l of the road, xx ft xx (direction) from the c/l of the power-line, xx ft above or below level with the ground, xx ft above or below level with the road and xx ft xx (direction) from a witness post.

 

Q: Is it necessary to give a direct straight-line distance (diagonally across the road) from the pole to the station?

A: YES, this is less confusing

 

note

c/l = Centerline

(direction) insert the compass reading here

Also if you have a compass you can list the directions as, N15W or N-15-W etc The degree symbol ° is not recognized by the NGS program

 

NNW is ><N22°W

NW is ><N45°W

WNW is ><N67°W

 

>< = more or less

Edited November 22, 2004 by elcamino

[evenfall]

Hi Holograph,

 

This is a great question, I an glad you asked.

 

A Compass and 100 foot tape measure would be very helpful but there is a work around.

 

You did not say what kind of GPS you own but there are maybe some tricks you can use, should you have one that has enough features.

 

Ok, To Begin. NGS recoveries are in NAD 83 Datum, ddd.mm.sss format, so it is best to use that format on your GPS when dealing with them. It is especially important if you intend to cite the GPS waypoint you made in your recovery. It is a big help in describing the station especially on vertical control. It is also best for you when working with their datasheet, and it is best to work with their datasheet because the geocaching website conversion of format, rounds off some of the accuracy when they convert to ddd.mm.mmm format. Also when you are standing on location you will see that all the numbers match with no need to convert them.

 

Making a Waypoint for the Station by placing the GPS on the station and waiting for the highest accuracy you can get is best. Then include that coordinate in your filing. This is really only necessary on vertical control points, not for triangulation, or horizontal control, as these are already at a higher accuracy than your consumer grade GPS can reveal. You can determine what kind of Station you are recovering from the NGS datasheet.

 

Next check the settings in your GPS, If it has a compass, the compass heading north reference should be set to true. Not grid or magnetic. Now, stand at the Power Pole and run a go to to the waypoint you made for the survey maker. The GPS should give you a bearing and approximate distance to the survey marker. Then you could say "the the station is approximately X feet or X tenths of a mile N.W. of the power pole bearing 345 degrees". This is better than paces as nobody has the same stride and terrain can mess up paced measurements. Also double check this measurement 31 FEET WEST OF THE CENTERLINE OF THE ROAD. Is it still good? I ask because the centerline of unimproved roads can meander.

 

So your filing could say the tree blazes are no longer good, (do not re blaze the tree!) That it is X feet west of and at a right angle to road centerline at NNN degrees and X feet nnn degrees from a power pole on the opposite side of the road.

 

Feel free to look at other descriptions of stations to get a feel for how the technical writing style seems to go. Then just be as succinct as you can, while describing it as best you can. Most importantly if you have any more questions, ask anytime. Writing recoveries is not that hard once you have a feel for it.

 

Thanks, Rob

[Bill93]

I figured that the old NGS style of starting from a road intersection or "from the post office in Anytown ..." was obsolete. With handheld GPS coordinates. you can get within sight of the position by any route that is convenient, and they do change highway numbers enough to be problematic. What is really important is good ties to get you from the nearby landmarks to within inches of the disk.

 

Glad you mentioned height above or below the road or other feature. That can be really good info if landscaping or deposition hides the mark.

 

If you use trees, give the diameter, both for identification and so someone later can adjust for the growth.

 

Convention seems to specify from the middle of a road, railroad, or as here power line and from the near edge of a pole or tree. Some things aren't as obvious (where on a curb), so be very clear in the description.

 

The general idea seems to be to measure somewhere you can put a tape measure (not the middle of the tree), but the most permanent accessable location about the object (roads more often are widened symmetrically).

 

Which would you use, the edge or center of a sidewalk? Where on a fire hydrant? The edge of the concrete box at a storm drain, the edge of the manhole , or its center? What about a road that has an obvious joint in the concrete but that isn't the middle of the road?

[evenfall]

Bill,

 

These are common practices...

 

Railroad is usually referred from one of the rails, pick one and define it. East rail, west rail?

 

Which would you use, the edge or center of a sidewalk? Edge is best. Defined as front or back of walk, as seen from a street

 

Curbs can be defined as Flowline, Face of Curb, Top of curb, Top Face of Curb, Top Back of Curb... Tell us from where YOU measured. Top Back of Curb is most common, followed by Face of Curb.

 

Where on a fire hydrant? Top Bolt is most common practice.

 

The edge of the concrete box at a storm drain, We commonly use the edge or corner of the grate and define which one by cardinal directions

 

the edge of the manhole , or its center? Center of manhole is the only consistent location on a round object.

 

What about a road that has an obvious joint in the concrete but that isn't the middle of the road?

Centerline of road is always in the same place no matter where the cracks or joints are. Measure edge to edge and divide by 2.

 

Rob

[holograph]

Thanks, everyone, for all the information. I guess I'll have to get a tape and measure off the distance. I'm not sure about stretching a tape across a road, but the road isn't busy so it's possible. With luck winter weather will hold off until I can revisit the site -- we already had an early freezing rain and light snow on the 13th, and the return of winter is going to put a halt to my hunting until next April.

 

Looking at the notes for this line of 1942 benchmarks, it looks like the NGS searched for them in 1979, couldn't find most of them, and resurveyed and placed new stations along the same road. The new ones have nice solid metal witness posts with signs and are a little easier to find, but there are even a couple of the 1979 marks that I haven't found yet. There still aren't any structures along the road, and even many of the 1979 ones use blazed trees as ties. (e.g. LY2242, LY2244, LY2245, LY2246)

[Z15]

You can easily measure with just one person if; you get a tape measure that has an eye at one end and use a chaining pin or large screwdriver to push into ground to hold the dead end. I do that all the time. I have a Kesons 165 ft surveyors nylon tape from Forestry Suppliers. I u deicde to get one of these, get the 150-165 ft length, I find that works the best, 100 ft is oten a little to short...

 

Tip-If you are worried about stretching across a road, measure in stages. Eyeball a straight line by placing some rocks or something else on each side of the road. Measure to the first side and record, if nothing is coming measure across road and record. Then place you tape end at the safe spot and finish the measurement.

 

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Edited November 23, 2004 by elcamino