I read many new descriptions from different surveyors regularly. Some surveyors use the phrase "thence on a non-tangent curve to the......." routinely for almost every curve and supply the chord bearing and distance. Other surveyors never include the "non-tangent " qualifier and supply the chord bearing and distance. These descriptions are strictly for boundaries that are not tied to fixed conditions, such as a defined existing road centerline.
Which method prevails in your office? Is one more corrector than the other? 😀 😀
...to a 1/2 iron rod found for the beginning of a (non-tangent/tangent) curve to the (left/right) having a radius of xx.xx feet, a delta angle of xx°xx'xx" and a long chord bearing and distance of Nxx°xx'xx"W, xx.xx feet;
Thence, with said (non-tangent/tangent) curve to the (left/right), an arc distance of xx.xx feet to a (monument)...
Oregon statute calls for curves on subdivision plats to be labelled with radius, delta angle, curve length, chord bearing and chord length. While all that is not required by statute on other types of documents most surveyors include all that on surveys and legal descriptions. Thus:
..... thence 856.76 feet on the arc of a 429.99 foot radius curve to the left through a central angle of 114°09'46" (the chord of said curve bears N33°02'08"E, 721.90 feet); thence ........
or perhaps ...
...thence N89°52'59"W, xxx.xx feet to the point of curve of a 429.99 foot radius curve to the left; thence 856.76 feet on the arc of said curve through a central angle of 114°09'46" (the chord of said curve bears N33°02'08"E, 721.90 feet) to a point of tangency; thence N24°02'45"W, xxx.xx feet......
I would only specify tangency or non-tangency in cases where the curve was non-tangent. I would do that in other states as well. It's assumed to be tangent. Nevertherless, I will always include chord bearings and distances, because that is the local common practice. I might not do that in other states.
in New Zealand an arc is allowed for horizontal, but not vertical, boundary definition.
We have to show chord bearing, arc distance and radius
left/right, Delta, Radius, Arc Length, Chord Bearing, Chord Distance.
It is rare to see the delta included in the verbiage of the description here. Not sure why. It is commonly shown on the drawing, however. Radius, arc length, chord bearing and distance. Tangent or non-tangent is irrelevant in the general case where the chord bearing and distance have been supplied.
Our legal description programs included the delta as a default so I guess we just followed along. Looking back at some pre-computer descriptions I helped write they are different. There didn't seem to be a standard format.
NC requires bearing and distance of the long chord. General practice is to include radius and arc length along with the chord data.
Most surveys I see attempt to define the center lines of rivers, creeks and other water ways in detail, including numerous curves. A recent example was a case of an out of state hunter buying all of the land between the centerline of a river and a large creek that both ran completely across the seller's property. The price per acre more than justified the cost of the survey. Of course, no monuments were set. The curves, of course, are basically a joke and the descriptions as well. They are strictly an exercise carried out to develop a "scientific" area for the sale.
On the other hand, I still see surveys that skip any pretense of descriptions and use the old "thence xxxx feet more or less northwesterly and westerly" approach.
ur legal description programs included the delta as a default so I guess we just followed along. Looking back at some pre-computer descriptions I helped write they are different.
If I were survey emperor I would probably require delta, radius, and arc length be shown on tangent curves. Together with the tangent bearings everything else can be computed, with elements to spare. I'd only require chord information on non-tangent curves.
BTW - if someone wants to routinely specify that a curve is tangent I'd allow it, as a reviewer. Just as I wouldn't reject a description repeating the phrase "to a point" ad nauseum for that reason alone. But certainly I discourage the practice.
If a curve is non-tangent, I will always identify it as such; failing to do so is unsatisfactory IMO. As for items defining the curve, I much prefer using radius and central angle (delta). Chord bearings are not commonly used here though I have seen them before.
Spiral curves are a whole 'nother animal in and of themselves, of course...
The only superior evidence is that which you haven't yet found.
@crashbox The chord bearing and distance have appeared in every survey including curves that I have ever reviewed. One of the great things about RPLS.com is learning the differences in local preferences.
Another example of preferences by location is whether or not the survey drawing shows ownership, record data, etc. for all adjacent properties to the tract surveyed.
I don’t say that a curve is to the left or right in a description, I state its direction of concavity “… to the beginning of a curve concave to the southwest, having a radius of…”Why? Well the port side of the boat is the port side no matter if you are facing the bow or the stern. Does it really matter? No, but that’s what I do.
@david-baalman That is only used by surveyors in areas that border an ocean. 🤣 🤣
So the big question is what elements do you hold when the deed measurements don't fit the monuments on the ground? Do you make it non-tangent? Change the radius to fit? Set a new pin at the calculated point of tangency?
(Time to duck and cover or put on my asbestos underwear as they used to say)
Curves created in new tract descriptions are frequently mythical. One, there may be no monument set at either end. Two, the end points are rough approximations to begin with. These are attempting to describe the center line of some water flow circumstance. Some, in rare cases, might be attempting to define where an underground line runs without digging it up. Others are the center line of an abandoned railroad where all ties and rails are missing and monuments will be set at both ends and possibly intermediate points for new fence construction purposes.
I do generally hold the monuments when they exist, and I try to hold whatever element appears to be the defining element of the curve, which per Wattles is the one that’s a round number. Usually that’s the radius ( or perhaps degree of curve which is ultimately the radius as well). When you have found monuments at each end and hold one element, the rest have to give. Delta, arc length, tangency all yield the way I do it. Tangency is the least important element in my mind. I can easily explain to the layman that the monument we are looking at is the beginning of the curve. How do I explain that it only controls for direction and the actual start of the curve is over here so that we wind up with a perfect 90 degree angle from the back or ahead tangent to the fictitious radius point? And more importantly why would anyone care if it’s slightly non tangent in the real world?
My question is Why would anyone create a non-tangent curve when software these days nearly does all the work for you? I still have teeth marks on my backside from the time I created a non-tangent curve and Dad did the mapcheck... Most young folks in the profession these days don't know the basic elements of a curve nor how they work.
Me. "What's the difference?"
T.C. Carroll "It's the difference between right and wrong!"
Exactly. Picture a four-wheeler trail through a somewhat dense pasture full of half-grown trees and briar bushes. The task is to create a description for an ingress/egress easement 20-feet wide by defining the "existing" center line. Two of the resulting segments were defined by non-tangent curves.
In a significant number of cases where the surveyor took a large number of shots to locate a creek because the center line would be the boundary line of a new tract, they will draw a neat looking center line based on those shots. Then the description reads, "thence southeasterly along the center line of Mud Creek 3037.04 feet, more or less" Talk about unneeded digits. If another surveyor had been there later the same day and used a similar method of having the means to draw a nice looking center line on the survey plat, his resulting number might be 50 feet different from the above number.
@holy-cow I don't compute curves for creeks, rivers, etc. When the centerline is the property line it's a mute point. Highways, roads, railroads, etc. I compute tangent curves unless there is some crazy reason not to.
Me. "What's the difference?"
T.C. Carroll "It's the difference between right and wrong!"