I have been reviewing and QAQC'ing several land descriptions from another company, somewhere around 45 thus far. I have frequently found usually minor, but sometimes more than minor discrepancies in the reported areas (most of these descriptions contain less than 2 acres, so typically we are talking square feet). One such check today was a centerline strip description that was approximately 4700 feet in length and 10 feet in width, being 5 feet on either side of said centerline. So I offset the centerline and created a closed polyline boundary, and then I create a parcel from this in CAD. This gives me one area calculation. I then just add the total CL distances and multiply the sum by the width as a check, pretty simple stuff. My calculations check within a square foot of one another, but the author's area is 20 square feet more. When I contacted the author, he stated that he uses a separate non-AutoCAD software to perform his closure reports and area calc's. His idea is that running the closure reports within CAD is not an independent check. At this point I am calling him off. With today's software and CAD generated closed figures, I do not find a 20 foot square foot descrpeancy reasonable in this size of an area. I do have his closure report and I have verified that all perimeter courses and distances check with the report I ran, but the areas do not match within what I expect to be reasonable? What say you?
Howdy CVNevada, welcome to the site.
Try using a COGO program to insert the deed calls and create new coordinates and check closure and acreage.
Most expense for easements are computed by length or acreage.
Until 20 sqft makes a significant difference.....not gonna worry about.
The math should support itself, in that when done correctly, it should yield consistent results.
The evidence in the record document with distances and calls in a metes and bounds can vary from the plan or cadd file.
20 sqft does appear too much.
Assuming that this is not a four sided tract. Comparing entered distances into a map check program to the nearest 0.01' and a closed CAD polyline on a long narrow tract will often be affected by rounding error. A distance of 10.000426 * 4700 will yield an increase of 20 Square Feet.
"...5 feet on either side of said centerline"
So it is a 5' wide strip...
20 square feet is 0.0004 acres or 4 ten-thousanths of an acre. I don't know any surveyors or any quality that would report acreage to 4 decimal places. Also, over that length, his side distances could have been 10.004 feet, which would round to 10.00 feet, and still generated the extra 20 square feet.
I wouldn't worry about this. I was going to say it could be in that the side lines are lengthened or shortened due to the opposite lines not being square, but I see that is not an issue but will not allow someone to use L*W to check the acreage/square footage.
lmbrls, post: 455638, member: 6823 wrote: Assuming that this is not a four sided tract. Comparing entered distances into a map check program to the nearest 0.01' and a closed CAD polyline on a long narrow tract will often be affected by rounding error. A distance of 10.000426 * 4700 will yield an increase of 20 Square Feet.
I see your point, however back in the office this morning, I now have one that is off 6.3 s.f. in only 1,069.18' linear feet, so that would mean he's off .03' on both sides? I still have another 40 to 50 of these to review, and I believe there is a systematic error issue with his mapchecks. Thank you for giving me another perspective! 🙂
10.005892 * 1069.18 increases by 6.3 s.f.
lmbrls, post: 455713, member: 6823 wrote: 10.005892 * 1069.18 increases by 6.3 s.f.
Yep. Less than a hundreth.
Kris Morgan, post: 455677, member: 29 wrote: I wouldn't worry about this. I was going to say it could be in that the side lines are lengthened or shortened due to the opposite lines not being square, but I see that is not an issue but will not allow someone to use L*W to check the acreage/square footage.
:gammon:
How could you go wrong with width times length?
Dave Lindell, post: 455849, member: 55 wrote: How could you go wrong with width times length?
If it is a 4 sided figure, you should have the same answer. On a multi-sided tract, rounding will be a factor. I was taught in school to give greater care to the measurements of the short sides of long narrow tracts for the affect on area. Performing area comps by hand gives us a better understanding of how the software is computing area. Multiplying by 0.00 or by 0.00000000000 will give a different result that will be apparent when the results are summed. Computers are great but they are limited by the same mathematical principles that have always existed.
Dave Lindell, post: 455849, member: 55 wrote: How could you go wrong with width times length?
I think you missed your emoticon for sarcasm Dave. 🙂 Surely you can see where someone would go wrong with L*W when they are quibbling over square feet in a route survey 3/4 of a mile long, especially if the ending lines are not 90?ø to the route lines. 🙂
Kris Morgan, post: 455876, member: 29 wrote: I think you missed your emoticon for sarcasm Dave. 🙂 Surely you can see where someone would go wrong with L*W when they are quibbling over square feet in a route survey 3/4 of a mile long, especially if the ending lines are not 90?ø to the route lines. 🙂
OOPs, new here, I didn't intend to hit the unlike, but oh-well. ?¨You don't think non-90?ø end lines can be accounted for? I will have more to come on this, but for now, let me point out that I am not talking some sort of retracement, but original creation of easements. Why not get it correct the first time, instead of beginning with slop?
This is why area is at or near the bottom of the pile when weighing conflicting evidence.
Larry Best, post: 455974, member: 763 wrote: This is why area is at or near the bottom of the pile when weighing conflicting evidence.
That's exactly what I was thinking. Had this talk with many a client.
CV Nevada, post: 455965, member: 13195 wrote: OOPs, new here, I didn't intend to hit the unlike, but oh-well. ?¨You don't think non-90?ø end lines can be accounted for? I will have more to come on this, but for now, let me point out that I am not talking some sort of retracement, but original creation of easements. Why not get it correct the first time, instead of beginning with slop?
First, it's not beginning with slop. Rounding off a hundreth or so of a foot is not what I would consider slop and I would encourage you not to accuse the subject surveyor of this when you are making independent calculations using centerline data and getting a number that is within 20 square feet over 3/4 of a mile. Second, if you use two different packages, you will get two SLIGHTLY different answers.
If you don't believe me, try this. Take the metes and bounds and pick a different corner to begin at. IT will give you a different answer. I was made to, and have made others when trying to teach precision, to take a traverse and compute it's closure. Then, once you do that, pick a different point of beginning and redo it. The difference in precision is amazing AND it's the same numbers you used to compute the first traverse with.
Obviously we can account for side lines that are not 90?ø when computing acreage, BUT you cannot do it with L*W, especially if you're worried over 20 square feet. Really, it's a strip of land, less than 1/8" wide, for the route length. I agree with wanting precision amazingly close, but it's important to keep an idea of the differences in number.
Your conundrum is exactly why I hate being forced to report quantities in square feet rather than acreage because I can use two different CAD packages with the same coordinate values and get different numbers and they're both correct.
de minimis non curat lex
The trick is figuring out what that threshold IS.
:bomb:
Loyal
Kris Morgan, post: 455677, member: 29 wrote: I don't know any surveyors or any quality that would report acreage to 4 decimal places.
You obviously don't work around here. 4 places is common, and I've seen 6 places on a large farm survey. Clueless, just frickin' clueless.....
wow... I almost posted a reply 4 different times. I am biting my tongue. I must be getting older. Hopefully a little wiser.
Larry Best, post: 455974, member: 763 wrote: This is why area is at or near the bottom of the pile when weighing conflicting evidence.
There should be nothing "conflicting" when creating a simple easement. My client pays by the area, and it should not be difficult for two surveyors to calculate very near the same area in a simple newly created easement. The author of these easements is using a secondary program to check his closures, and these closure areas are not as consistent as they should be. Some of these are centerline strips that have secondary strips forking from them. I will typically make a closed figure of the entire area (looks like an amputated centipede), and then check the sum of the parts against the whole. Again this is in the process of being created, NOT retraced, I think some principals are being confused here. If you subdivide land, do you ensure sum of the area of the subdivided lots equal the original area? I do!