Really bad plat

on the assumption it's a tangent curve it would seem like you could easily calc the curves on either side of it and go from there.

Preliminary plat that was recorded before draftsman completed drawing.

In Block 7 the lots are not numbered.

Once some developers get their hands on a drawing they head straight to the recorder and file it as is and then fire the Surveyor.

As fit it to the rest of the Block and make the measurements work.

good luck

well, i still can't figure out what bugs there are that keep my main account (flyin solo) from working like 98% of the time anymore, but here's what i came up with for that curve, holding the stated bearing on the south line of Lot 5:

R=68.43' D=125°35'20" ARC=150.00' CB=N41°05'23"W CHORD=121.72'

looks like it is either non-tangent or there is a +/- 2.5' bust in there somewhere.  that's by building all the lot lines per B&D and constructing the resulting curves.  (i got radii of 671.85 and 376.64- guessing they are supposed to be 670 and 375)

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I donƒ??t believe itƒ??s a preliminary map, I think you have mentioned your from the Asheville area, we have three subdivisions here that look identical to the map you attached. My previous employer told me that someone from Asheville designed all three of ours in the seventies. If it was ƒ??Scottƒ? then Iƒ??m relieved we are not the only ones who have to deal with his crappy maps.

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The maps we have scale reasonably well so we bring in pdf and find a radius that works with the arc length, and existing monuments if there are any. None of the curves appear to be tangential so I wouldnƒ??t worry about trying to make them.

taking that, if you push a tangent reverse curve out from the northeast corner of Lot 5, holding a radius of 69.75 feet, that gets you within a couple tenths of the end of a 28' arc shown on the north line of Lot 4.

another consideration being that, on your lot, you're dealing with zero decimal places for record.?ÿ so if i had nothing else and got to between .51-.49 i'd be satisfied...

Jones

Unfortunately this plat was recorded in 1925. I run into these quiet often here in Asheville as nobody has updated the plats or deeds in a while.?ÿ

A Harris the section you are talking about is actually off of the map and is part of another plat.?ÿ

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Thanks everyone. I am still trying to learn some things in CAD and fortunately these kind of problems don't happen that often.

I zoomed in and printed that portion of the map, which came out to be 1"=60'±.

Holding a 70' radius (based on three equal distances from the ends and middle of the arc) and measuring the delta with a small protractor, I got 123.5°± which gives an arc length of 150.9'.

I would need more information for that 28' arc on the northerly side to calculate a closure.

I will go with chimeric's answer.

How many corners have you found?

I have found all three corners so this is just a matter of making the arcs work, which I am finding is an area my education may be lacking a little bit. 

Posted by: Dave Lindell

I would need more information for that 28' arc on the northerly side to calculate a closure.

I tried to fit a curve to lots 1,2, 3, and part of 4 in order to learn more about that part of lot4.  I find the radius to be a bit more than 400 ft maybe 408, but it doesn't fit both the corners of lot 2, with one long and one short, different by 1.6 ft.

Crossing the street and working out the radius on the opposite row might give you a clue as to what was intended. With the distances penciled in to the nearest foot though it might only be guide. At least it would be a thorough boundary examination.

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We have plenty of old recorded plats similar to the example shown.?ÿ Although one can (at times) calculate circular curves on these plats that fit the dimensional criteria given, I'm not so sure some of them were ever actually meant to be circular curves.?ÿ I have seen a few plats that were most likely drawn with a French curve (an antique drafting tool).?ÿ

Surveying within these plats can teach a surveyor a lot about understanding what was actually being shown on the document or implied by the document and what wasn't.?ÿ Assuming there is mathematical harmony and logic within some plats may just be wishful thinking.?ÿ

That is a bad plat.?ÿ Reminds me of a local subdivision that was created by an engineer that worked heavily on railroad projects a long time ago.?ÿ As you can guess, all of the curves were railroad curves.?ÿ Total pain assured for anyone who didn't know the engineer's history.

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Paden, I agree wholeheartedly. This is part of the reason why I have the philosophy that curves are where the error lies 

In the late 80's I worked for an Engineer/Surveyor that had done many subdivisions just like that in the late 60's and early 70's. The party chief/old timer that did the fieldwork was still there and still the party chief. Those subdivisions were designed on the ground and surveyed enough to make a plat in the office. There was no design and go stake it out. Any distance that was not measured on the ground was scaled between the dots on paper.

That 150 foot is the length of the arc and may have been measured with a cloth tape sorta draped around the arc where they wanted the line. Forget math, there was none.

James

Remember stories of an old timer that staked the strait lines, then turned a deflection angle to the end of the other straight line.  Once that was done cloth taped a distance and used curve table in field book to determine arc distance. Everything fit within a foot or so and nobody could measure the arc distance anyway.

Check the deeds. There are plats of this type recorded in the Portland area. Sometimes the lots are described by M&B in the deeds, thus filling in missing information.?ÿ

Norman believe me I looked. The deeds all call for being all of lots from PB PG etc etc. except for the lot to the south, however the M&B is out so bad it was useless. 

Any solution that does not take the field evidence into account is likely wrong.

It's nice when records are neat and tidy, but they are only part of the picture.