Availability: All plans. Role: edit access on the project.
What you are seeing
A curve in the description will not take. Either the line carries an error marker in the manual plotting editor, or the document came back from the AI with a Complex Curves warning saying it is not expected to plot correctly.
Two quite different things produce this, and only one of them has a fix.
Compound and reverse curves written as one course
A single course carrying two arcs: a compound curve with a first and a second radius, or a reverse curve turning the other way, described without a break between them. Trace rejects the line on the word joining the two arcs:
Unrecognized curve parameter "then"
The whole line is then left out, while a simple curve after it plots normally, so the description quietly loses one arc and keeps the other.
The fix is real, and the geometry was never the problem. Only the single-line notation is unsupported. Split the course into one curve line per arc, each with its own hand and its own parameters, and it plots with no error. A reverse curve is simply two ordinary curves of opposite hand.
| Instead of | Write |
|---|---|
| One course carrying a compound curve, two radii, joined by a word | Two curve lines, one per arc, each with its own R and one more parameter |
| One course carrying a reverse curve | Two curve lines, the first L and the second R, or the other way round |
Each arc needs a hand and enough to fix it: a radius plus an arc length, a central angle, or a chord. A curve with no hand returns Curve requires direction (L or R), and too few parameters returns curve data insufficient. The first curve of a tract also needs a chord bearing or a tangent, because a tangent curve takes its direction from the course before it and there is none. Deed syntax reference lists every parameter, and Lines curves and calls has the form that writes these lines for you.
Spiral curves
A curve described with a spiral length and two radii, one at the start and one at the end, or named a spiral, a transition or an easement curve.
Spiral curves are not handled. Trace has no spiral form at all, so the line is not a curve written wrongly, it is not a curve. In the editor it returns:
Unrecognized direction "spiral"
The line is then left out and the courses around it report a closure error roughly the size of the missing run. On the AI document path the same language raises the Complex Curves warning.
There is no workaround and no setting for this. Where an alignment carries spirals, that part of it is survey work.
Curves that do plot, and are worth not fearing
- A tangent curve along a road margin. It takes its direction from the course above it, which is the usual way a deed writes one.
- A curve given as a degree of curve, or with the radius left to be solved from the other figures.
- A major arc. A central angle over 180 degrees draws as the long way round, as described.
- A curve with a monument on it. Monuments label the point and never change a computed value.
A chord that cannot exist is caught rather than drawn wrong: Chord 500 ft is longer than the diameter of 200 ft, or Chord 500 ft is longer than the arc of 100 ft.
If that did not work
- The curve line is rejected but reads like a valid curve. Free text on a curve line is read as a mistyped parameter, and a
MON:among the parameters returnsUnclosed string literal. Put monuments after the parameters. - The curve plots but bulges the wrong way. Check the hand.
LandRare read as written, and reversing one turns the whole arc. - The document warned about curves but the plot looks right. Check the course count against the description. A dropped arc does not always show up in the closure figures. See When a call will not plot.
Related
- Lines curves and calls, for building a curve with the form
- Deed syntax reference, for every curve parameter and message
- What Trace can and cannot plot, for the four outcomes
- When a call will not plot, for a course that was left out
- The document queue, for the Complex Curves warning