I am fine with most comments, but I am not sure why one comment was necessary on the parcel map which I am working on. It is a two lot split of a 105.33' wide parcel, so I put each parcel as being 52.665' wide just because of the obvious rounding error makes it look odd to me without the .005' to correct it.
The comment was that the boundary lines must be resolved to the hundredths of a foot, and one parcel needs to get the extra hundredth, and then the closure calculation needs to reflect the new numbers.
I dont really get the need for this at all. It is not something I am going to make an issue on, but it just seems strange to make a comment about it.
And emailing the person to inquire seems too weird, since we are talking such small numbers. I suppose I will just do it, but it seems silly.
I am spending a lot of energy on a half hundredth!
> I suppose I will just do it, but it seems silly.
After repeatedly running into this and related rounding issues in my city about 20 years ago, I realized that if I kept complying with the map checker demands the matter would never get resolved in a reasonable manner. So we sat down with the Public Works director and came up with a note that now appears on all Final and Parcel Maps:
The sum of the individual parts of a given line or curve may not equal the overall quantity due to rounding.
Problem solved, and everyone's happy.
> > I suppose I will just do it, but it seems silly.
>
> After repeatedly running into this and related rounding issues in my city about 20 years ago, I realized that if I kept complying with the map checker demands the matter would never get resolved in a reasonable manner. So we sat down with the Public Works director and came up with a note that now appears on all Final and Parcel Maps:
>
> The sum of the individual parts of a given line or curve may not equal the overall quantity due to rounding.
>
> Problem solved, and everyone's happy.
But why do they care? What is the point they make about this when it has come up?
(Also the issue of the closure calculation implies I have to edit the closure to make it appear to work.)
Bryan,
They don't understand. That is what makes it so frustrating. Jim, that is an excellent solution.
Ed
Call me crazy but I would most likely just list the overall distances 105.34' and resolve the matter with the knowledge that my accuracy of measurement is not compromised for .005'.
CV
First Off Is The Parcel A Perfect Rectangle ?
Very few are, so I would divide by equal area, to the nearest 0.01' measurement.
Paul in PA
i actually agree w/ the map checker. displaying distance measure to the thousandth is awkward when it can so easily be avoided. If the parent lot was 105.33 wide on both front and back lines, I probably would have balanced it w/ one lot getting the extra 0.01 on its back line, and the other lot getting 0.01 on its front line, just to avoid that very thing.
> The comment was that the boundary lines must be resolved to the hundredths of a foot, and one parcel needs to get the extra hundredth, and then the closure calculation needs to reflect the new numbers.
This is good to know that Western Civilization is being defended against the Visigoths of surveying by a few stalwart map checkers stationed at some lonely outpost of the Empire.
I wonder if the original specification was intended to eliminate distances expressed to the nearest 0.1 ft., but that it has morphed in enforcement efforts to protect the landowning public against the ravages of the nearest 0.001 ft.
First Off Is The Parcel A Perfect Rectangle ?
I thought of CV's solution, but if the existing parcel is an odd number, it is what it is. You've got a 50/50 chance every time you try to equally divide a parcel that it will be even or odd so it's a minor issue that should have a standard way of resolving it. They have to "draw the line" somewhere. What if you had a 200.05' parcel that you want to divide into four equal lots? I've seen Jim's note before and that seems to be the most logical solution. This comes into play with proration all the time too. Generally, an equal proration will not result in a perfect hundredth lot width. Either stagger the lot dimensions like the map checker suggests or talk them into a note like Jim did. It really doesn't matter to anybody but surveyors, but it's one of those things we have to think about.
Side note: Is this some kind of ordinance that the boundary resolution has to be to the hundredth? I often wonder how much more authority the local jurisdiction has about the form and content of Parcel Maps versus Records of Survey. On ROS's you can pretty much thank them for them for their opinion and ask that they file the map as-is.
Round the sucker off
it makes life a lot easier!
Round the sucker off
I might agree to round the sucker off if I was determining the width of the existing parcel that's being divided independently of any previous recorded width. If Bryan is coming up with the record width that happens to be an odd number, changing it to an even number for convenience's sake presents its own problems. The whole significant figure issue is one that we deal with every day. A surveyor goes out and locates a dirt road center line and describes it with bearings to the second and chords to the hundredths, that's laziness to me, but that's what the computer says when you pick the nodes so that's the way the description gets written. Our equipment and our conventional ways of reporting directions and distances are not really that compatible.
First Off Is The Parcel A Perfect Rectangle ?
It seems to me on proration it is SOP to give the extra hundredth to your client except for some it is SOP to throw it into the adjoiner's lot. For example, 1320.01, one lot gets 660.01 and the other gets 660.00. This seems pretty typical.
Round the sucker off
We are using 21st century equipment and reporting our results in a 19th century system.
They used bearings and distances because that is what they measured. Often 19th century maps don't close mathematically because they weren't doing plane surveying.
Now we are measuring mostly from random traverses or GPS vectors yet we report as if we actually measured the bearing and distance of the line which we did in a secondary way.
Round the sucker off
The lot dimensions are all prorated in, so I would have to get creative with it if I started playing with the original lot dimensions.
I did not pay attention to this when posting, but ironically, the original subdivision map, dated February, 1920, shows the original lots as being to the thousandth, which gave me a good chuckle just now. I show the lots as now being 105.33 feet and record as 105.304' as per the map.
How dare that original surveyor. Bastard.
1920 to 2010: A Spatial Measurement Odyssey
> I did not pay attention to this when posting, but ironically, the original subdivision map, dated February, 1920, shows the original lots as being to the thousandth, which gave me a good chuckle just now. I show the lots as now being 105.33 feet and record as 105.304' as per the map.
>
> How dare that original surveyor. Bastard.
Damn good thing there are now map checkers to keep all those confusin' thousandths locked up. No telling what sort of chaos has ensued in that subdivision for the last 90 years as surveyors fretted over which landowner to give the extra couple of thousandths to.
okay here is the secret
The new lots are 53.67 and 53.66. done my invoice is in the mail.
okay here is the secret
> The new lots are 53.67 and 53.66. done my invoice is in the mail.
That is what I will do, and I like Jim Frame's note just to cover things.
BTW it is not you
It is not you, it is the checker. I have had at least one licensed surveyor map checker insist that I do something with the 0.01'. The city of Livermore requires dimensions to three places. I am glad for the post tho cuz Jim's note is a good one.
You know well the mon maps of San Francisco, that show distances to 3 places.
BTW it is not you
> It is not you, it is the checker. I have had at least one licensed surveyor map checker insist that I do something with the 0.01'. The city of Livermore requires dimensions to three places. I am glad for the post tho cuz Jim's note is a good one.
> You know well the mon maps of San Francisco, that show distances to 3 places.
Yes San Francisco is another good example of that for old surveys.
Interesting about the City of Livermore. I have not dealt with them before.
Round the sucker off
Just think: if that 1920 map had only shown 105.303 and you accepted it-then you could have split the distance and shown 52.6515-which would have really sent him into a spin.
And it's not just the distances. What to do with that .01 Acre, and when the local board was rewriting subdivision reg. someone put in a preliminary draft that areas were to be expressed on smaller lots to .01 square foot. Of course that would be really useful.
I have to admit that I've had the same situation and I made the 105.33 105.32 because the inverse was 105.326. Of course if you have a string of lots you can chase that .01 endlessly