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Thread: How property lines are located on actual site to centimetre precision.

  1. #1
    Cyburbian
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    How property lines are located on actual site to centimetre precision.

    I am studying a case where A sued B for encroachment because B built a retaining wall along their property line that went 0.07m over onto A's land. (Of course B's wall actually benefited A as it prevented any possible landslides under heavy rain conditions. A just hated B and sought a mandatory injunction.)

    But my question is how do property lines get translated from maps on to the ground with such precision? Does B have a case to saying that he built the wall EXACTLY within his land, the measurement is simply inaccurate.

    ps. Sadly, A actually won.

  2. #2
    Cyburbian Raf's avatar
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    Quote Originally posted by vxw View post
    But my question is how do property lines get translated from maps on to the ground with such precision? Does B have a case to saying that he built the wall EXACTLY within his land, the measurement is simply inaccurate.
    Legal description followed by survey completed using GPS technology. Said GPS technology will give an accurate legal description, hence to the tee of .07m Legal description are required as a part of plat/subdivision maps and are recorded at the assessors office of a local jurisdiction for real property.
    Men do dumb $hit... it is what they do to correct the problem that counts.

  3. #3
    Cyburbian
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    Thanks for the quick reply.
    I can imagine someone going to measure with both parties looking over shoulder. Much like the first down chain in football... 4th down and inches, sorry pay up.

  4. #4
    Cyburbian
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    Most communities, if not all, have one or more basis or bearings, a point that is known where survey measurements are taken from. Once other areas are surveyed additional known markers are left that other surveyors can work from. Using a known point that is detailed on the subdivision plat, a surveyor using his equipment -- generally GPS these days --, can start to layout points on the plat that are then established in the ground with markers. The surveyors using computer guided equipment work from point to point. You can often see a nail in the top of the curb for the location of the property line at the street. Sometimes a marker of some point is left at the corresponding rear property line.

    Its painstaking work, but when it comes to property, ownership and construction, hundredeths of a foot can somtimes make a difference.

  5. #5
    Cyburbian Otis's avatar
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    Does GPS give that much precision? I guess if you capture enough satellites and a ground beacon or two. What I see is surveyors starting ata benchmark of known location, then using laser surveying instruments to establish lot lines. The laser equipment gives precision to at least 0.01 foot.

  6. #6
    Cyburbian
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    With the number of satellites available today, GPS has become pretty accurate, not like a laser scope but accurate enough for a lot of surveyor work today. Its value is in its speed.

  7. #7
    Cyburbian Emeritus Chet's avatar
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    Centimeter precision is NOT accurate enough! Most survey tolerances around here are within 0.001.

  8. #8
    Cyburbian
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    Survey quality GPS in static mode is accurate to 3mm (+.5 ppm) That is about 0.01 feet or 1/8 inch. In RTK mode is accurate to 10mm (+1 ppm).

    Positional tolerance on an ALTA survey is 20mm (+50ppm)

    I would never even pretend to measure anything closer than 0.01 feet. The 0.07m in question equals .23 feet or almost 3 inches.

  9. #9
    Cyburbian
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    Interesting, I've never seen the nail-in-curb before but it's a good idea. I mostly do measurements after construction, to make 3d building models. But as mentioned above, I'm also often skeptical of my leica giving me millimetre precision the surface finish sometimes throws it off. Then it's time to break out the tapemeasure-tug-of-war method.

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