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How To: Create a parcel arc greater than 180 degrees

Summary

When digitizing a parcel from a legal description, sometimes a curve greater than 180 degrees is described, such as at the end of a cul-de-sac. In a parcel traverse, a curve can be defined in terms of a Bearing, Radius, and Chord. For instance:

  • Radius: 100.00'
  • Chord: 146.40'
  • Bearing: S00-59-26W
However, entering the values as given in the legal description results in an arc smaller than 180 degrees. With a positive chord value, the arc will be less than 180 degrees.
Arc less than 180 degrees

Procedure

When viewing the parcel drawing, note the position of the center point of the arc; it is to the left of the curve. The desired center point is on on the other side of the curve, with the arc drawn in the opposite direction (and not showing). The solution is to use the negative of the chord value. This produces an arc greater than 180 degrees.
Arc greater than 180 degrees