Map Check

Don't they give you a closure calc sheet?

I do a true map check calc with area in Excel where I key in the bearings and distances from my map. It takes just a few minutes and catches simple errors.

Dave Karoly, post: 453424, member: 94 wrote: Don't they give you a closure calc sheet?

I do a true map check calc with area in Excel where I key in the bearings and distances from my map. It takes just a few minutes and catches simple errors.

i don't get them for what i do. but it doesn't even have to go that far. in carlson at least, you can verify closure to your preferred tolerance (i default to .02) just by selecting lines. takes about a half a half a second.

It's partly the law of unintended consequences. The powers that be require maps to be checked, this actually wasn't always the case.

Then the people sending in the map get so far with it and decide that you may as well be a check, so they put a certain amount of effort into it and let you red line if for them, that way you are doing some of the work for them, less cost to the client.

When I submitted Green Acres Surveys here in NJ to the DEP, a map check or closure calculation sheet is part of final submission. One of my old bosses also had a check list that had to be completed before he reviewed it and a map check was part of his requirements. The new school should learn from the old school.

MightyMoe, post: 453437, member: 700 wrote: It's partly the law of unintended consequences. The powers that be require maps to be checked, this actually wasn't always the case.

Then the people sending in the map get so far with it and decide that you may as well be a check, so they put a certain amount of effort into it and let you red line if for them, that way you are doing some of the work for them, less cost to the client.

These are signed and sealed plats.

Many CADD operators line work does not connect to the actual downloaded coordinates.
When they label things, wrong values appear.
I was told once that it took too long to draw things that accurately.
That man went back to the fieldcrew.

Dave Karoly, post: 453424, member: 94 wrote: Don't they give you a closure calc sheet?

I do a true map check calc with area in Excel where I key in the bearings and distances from my map. It takes just a few minutes and catches simple errors.

When we specify the survey, that is the case. Many times we get an area summary instead. Sadly some Surveyors seems to lack understanding about what constitutes a Map Check even after we explain it to them. We have gotten the reports Solo references and found that sometimes the annotation on the plat did not match the digital file. I can only speculate as to why this was the case.

We check all information on every plan. This includes closures of all lots. It is done totally independently of the original drawing file. We look at it as if another professional has picked up the plan and doesn't have our CAD file.

MightyMoe, post: 453437, member: 700 wrote: It's partly the law of unintended consequences. The powers that be require maps to be checked, this actually wasn't always the case.

Then the people sending in the map get so far with it and decide that you may as well be a check, so they put a certain amount of effort into it and let you red line if for them, that way you are doing some of the work for them, less cost to the client.

That was my experience as a plat reviewer, though some were more blatant about it than others. On the other hand I've worked with a lot of US Surveys that never seemed to close. There was nearly always a significant misclosure of boundary data of anywhere from a foot to three that could not be completely explained by rounding bearings to the nearest minute and distances to the link. I gathered that they were intentionally not adjusted so as not to sweep errors under the rug, but that was just my take.

Williwaw, post: 453451, member: 7066 wrote: That was my experience as a plat reviewer, though some were more blatant about it than others. On the other hand I've worked with a lot of US Surveys that never seemed to close. There was nearly always a significant misclosure of boundary data of anywhere from a foot to three that could not be completely explained by rounding bearings to the nearest minute and distances to the link. I gathered that they were intentionally not adjusted so as not to sweep errors under the rug, but that was just my take.

I'm not sure what you mean by "US Surveys" but if you mean GLO/BLM surveys I believe that they are reports of actual measurements made, not a report of how those measure were "adjusted" to produce a "mathematical closure." If you read the Manual(s) you will find that they had a specified allowable closure per section (or per mile). I don't believe that adjusting measurements to achieve perfect mathematical "closure" was within their purview.

I believe that mathematical closure of survey measurements stems from title companies, who knew enough to be harmful, and started requiring it of us in boundary descriptions. When I get to thinking about it it makes me nervous that I usually report some "adjusted" measurements in lieu of actual measurements. I am all too familiar with Star*Net and with probabilities, but it seems somewhat disingenuous to report massaged numbers as actual distances and directions. I have been amused over the years reading statements by others expaining that some reported measurements are real while others are adjust, all the while without specifying which are which. We even had one local firm that stated that they had never checked the validity of the information produced by their software.

I have contemplated reporting actual measurements throughout my career, but can't quite seem to get over the hurdle of "this is how we've always done it."

Jim in AZ, post: 453455, member: 249 wrote: When I get to thinking about it it makes me nervous that I usually report some "adjusted" measurements in lieu of actual measurements.

Raw measurements, using only the information you got from the tape or instrument, are an estimate of the distances and bearings with some amount of random error. They ignore an additional piece of information that is available for free. Wouldn't you want to use all of the available information?

That piece of information is that it was a closed traverse. A proper adjustment using that fact will statistically give estimates of the distances and bearings that have smaller error.

Bill93, post: 453472, member: 87 wrote: Raw measurements, using only the information you got from the tape or instrument, are an estimate of the distances and bearings with some amount of random error. They ignore an additional piece of information that is available for free. Wouldn't you want to use all of the available information?

That piece of information is that it was a closed traverse. A proper adjustment using that fact will statistically give estimates of the distances and bearings that have smaller error.

No, that's not the standard. The original plats you get are not about statistics.
Statistics have been a part of surveying for a very short time really. I don't think old Abe was too worried about them.
Plats are also true north so you have to calculate them that way if you want the real closure.
Recent plats will close pretty well, I doubt even with GPS they are put under any statistical analysis, although I could be wrong about that.

Jim in AZ, post: 453455, member: 249 wrote: I'm not sure what you mean by "US Surveys" but if you mean GLO/BLM surveys I believe that they are reports of actual measurements made, not a report of how those measure were "adjusted" to produce a "mathematical closure." If you read the Manual(s) you will find that they had a specified allowable closure per section (or per mile). I don't believe that adjusting measurements to achieve perfect mathematical "closure" was within their purview.

I believe that mathematical closure of survey measurements stems from title companies, who knew enough to be harmful, and started requiring it of us in boundary descriptions. When I get to thinking about it it makes me nervous that I usually report some "adjusted" measurements in lieu of actual measurements. I am all too familiar with Star*Net and with probabilities, but it seems somewhat disingenuous to report massaged numbers as actual distances and directions. I have been amused over the years reading statements by others expaining that some reported measurements are real while others are adjust, all the while without specifying which are which. We even had one local firm that stated that they had never checked the validity of the information produced by their software.

I have contemplated reporting actual measurements throughout my career, but can't quite seem to get over the hurdle of "this is how we've always done it."

I'm with you Jim, I just did a job, one of the requirements was a closure, I don't know who might look at it, but I ran an adjustment, printed out a report and threw it into the file. The thing was 8 pages long, beyond looking at it to see if there are any red lines and that it passed at 95% it is totally useless to me. The good thing is that it took almost none of my time.

Reporting actual measurments has a lot of validity, that the figure won't close isn't all that important.

lmbrls, post: 453414, member: 6823 wrote: I review plats from several states and have found that about 25% of the time the plat does not close. I don't mean a small error because of a flipped bearing, rounding or even unadjusted field error. I mean distances of several feet that were inadvertently left off the survey or bearing and distance that are just wrong. Many times the survey will appear professional and very detailed. They just don't close. I am not wanting the survey to have problems, so I can pat myself on the back. I actually want the survey to close. It pains me to see in many cases apparently much effort put into a survey to see it fall short because of the omission of a simple procedure. The error is so apparent that it is rare I can't determine where it is with very little effort. I was taught that a survey never leaves the office or is signed until a map check is performed. This is entering the bearing and distances taken from the hard copy of the survey. An area summary of the graphical file is not a map check. When I was in private practice, I had several technicians tell me that my old school approach was no longer necessary with the new software. The ones who learned the error of their ways had continued employment. Sorry for the rant. This is so basic and unnecessary.

I feel your pain. I have reviewed hundreds of plats (the only survey item in WA or ID that actually receives a closure review by a municipal agency). I can usually tell by the PLS on the plat whether it will close or not before i even start cranking out #s. It all comes down to a proper procedure and understanding on the drafting side of things which i why i never use drafters for survey work, i use survey technicians that understand survey. Its not that the PLS's that are constantly submitting maps with poor closures are bad, they just don't have a process in place to make it right. some of the best, most knowledgeable surveyors i ever worked with couldn't manage their way out of a paper bag. This doesn't mean they are bad surveyors, just bad managers. This relates directly to the survey related map products as well. You could be the best surveyor this side of the Mississippi but it you cannot communicate your survey on paper, it doesn't work too well.

I map check every plat. The Board checks plat in different counties for violation. Also I have seen plat that are out by feet also. I refuse to turn out garbage surveys. My 0.02 cents.

I do not work in a state where surveys get recorded, but all major subdivision and some minor subdivision do get recorded. Almost every time they require a closure to be listed right on the plan. It really doesn't take more than a couple minutes in CAD. You select the line labels and it tells you the colure ratio.

Assuming that the "map check" being mentioned is an inverse around the boundary of the tracts/lots (or the closure DP is describing) ... A map check is just one part of getting it right, Comping the boundary of all lots based on a plotted copy of the plat is another. Map checks don't show you where labeling is wrong, ambiguous, or missing. They don't show you where crows feet are wrong or missing. I'm a fan of Hack's approach.

Regarding the frustration of reviewing that cr@p: When I did that type of work on a regular basis, I had a stamp made that said "NOT Ready For Review" - Then it had some check boxes, I think they were "Please perform internal QC", "Please review the SOS", "Please see prior comments"
When I started reviewing a survey deliverable and it had more than a couple of edits, I quit reviewing and stamped it. Submittals are supposed to be final/near final - they can do their own draft markups.

Williwaw, post: 453451, member: 7066 wrote: I've worked with a lot of US Surveys that never seemed to close. There was nearly always a significant misclosure of boundary data of anywhere from a foot to three that could not be completely explained by rounding bearings to the nearest minute and distances to the link.

How about this one?

Loyal

Loyal, post: 453495, member: 228 wrote: How about this one?

Loyal

What is the date on it?