About the parcel fabric traverse tool

This topic applies to ArcGIS for Desktop Standard and ArcGIS for Desktop Advanced only.

The parcel traverse is the primary method for entering parcel data in the parcel fabric. For a single parcel on a survey plan or record of survey, dimensions for each parcel boundary are entered in sequence such that a closed polygon is formed.

The parcel traverse tool in the parcel editor facilitates data entry of parcels using information from plans and records of survey. Recorded dimensions are entered directly from the plan as well as other parcel information, such as the PIN, stated area, and parcel accuracy. When entering a parcel traverse, no set of coordinates or knowledge of a spatial reference is needed. All that is required are the parcel dimensions, which are on the plat or record of survey.

Parcel traverse units

The parcel traverse environment supports most of the common units used for representing recorded information on a plat or record of survey. Units are set in the plan in which the parcel is being created. To open the parcels' plan, click Plan on the Parcel Details dialog box. On the Plan Directory dialog box, right-click the parcels plan and click Properties to open the Plan Properties dialog box to set plan units. Each unique plan can have a different set of units.

Line categories and feature templates

When entering lines in the parcel traverse grid, you can specify both a line feature template under the Template field and a line category under the Category field. The line feature template is often used to set the line category. For example, you can define a subdivision line template that automatically sets the line category to Boundary and line Accuracy to 3.

Line categories are defined internally and are used to represent parcel structure. For example, if a series of boundary category lines form a closed loop, a parcel is created. A closed loop of connection category lines does not create a parcel. Line categories are also interpreted by the parcel fabric adjustment, for example, Road Frontages can be constrained to be collinear.

The following line categories are available in the parcel traverse grid:

• Boundary (line category 0)

  Used for the boundary of any closed loop parcel or unclosed parcel in the parcel fabric.

  In a fabric least-squares adjustment, the accuracy category of a Boundary is the same as the parcel accuracy category, unless otherwise specified. If no parcel accuracy category is specified, a default accuracy level of 4 is used.

• Dependent (line category 1)

  Used for lines that are dependent on parcel boundary lines, for example, easement lines. Dependent lines are part of the parcel, but do not define the boundaries of parcels; that is, a closed loop of dependent lines will not create a parcel.

  Dependent lines can optionally participate in a fabric least-squares adjustment, in which case they are treated in the same way as Boundary lines.

• Precise Connection (line category 2)

  Used for lines that connect a parcel point to a control point. Precise connections should start at the parcel point and end at the control point and should never start at the control point, that is, be oriented in the reverse direction.

• In a fabric least-squares adjustment, precise connections automatically have an accuracy category that is one level higher than the parcel accuracy category. For example, if the parcel accuracy category is 3, precise connections will have an accuracy category of 2.
  Caution:

  Precise connection lines should not exceed 50 meters (or 164 feet). In a fabric least-squares adjustment, long precise connection lines can effectively constrain the entire adjustment area along the line, making the least-squares adjustment solution unstable. If a precise connection line exceeds 50 meters, it is best to use a standard connection line.

• Connection (line category 3)

  Used for lines that connect parcel points. Connection lines are used to add connectivity to the parcel fabric to form a network that can be adjusted in a fabric least-squares adjustment. For example, connection lines are used to connect isolated blocks of parcels. Connection lines are part of the parcels sharing the points to which the connection line connects. Connection lines do not define the boundaries of parcels; that is, a closed loop of connection lines will not create a parcel.

  In a fabric least-squares adjustment the accuracy category of connection lines is the same as the parcel accuracy category unless otherwise specified.

• Radial (Line category 4)

  Used for lines that radiate out from the end points of curves to the center points of curves. Radial lines are automatically generated and maintained for curved boundaries. Radial lines are only displayed when a parcel is opened.

  In a fabric least-squares adjustment the accuracy category of radial lines is the same as the parcel accuracy category unless otherwise specified. For very long radial lines, an accuracy category of 7 (excluded) is recommended. This is because adjustments to long, flat curved boundaries can result in larger shifts in the curve's center points, causing the radial lines to become outliers in an adjustment.

• Road Frontage (Line category 5)

  Used for the boundaries of parcels that lie adjacent to roads or right-of-ways. When creating a new parcel, you could use the Road Frontage category instead of using the Boundary category for parcel lines that lie along roads.

  Note:

  Road frontage lines should not be used in unclosed parcels.

  In a parcel fabric adjustment, the accuracy category of road frontages is the same as the parcel accuracy category unless otherwise specified. Road frontages can also be constrained to be collinear in the adjustment.

• Origin Connection (Line category 6)

  Used for lines that connect a point of beginning to the starting point of a parcel. When creating a new parcel, an origin connection line is always entered first, then the remaining traverse lines of the parcel are entered.

  In a fabric least-squares adjustment the accuracy category of origin connection lines is the same as the parcel accuracy category unless otherwise specified.

• Part Connector (Category 7)

  Used lines that connect the parts and/or rings of a multipart or donut parcel. Part connection lines are automatically generated when multipart or donut parcels are migrated to a parcel fabric. When creating a multipart or donut parcel, part connection lines are used to connect parts and/or rings.

  In a fabric least-squares adjustment the accuracy category of part connection lines is the same as the parcel accuracy category unless otherwise specified.

Parcel traverse closure

When creating a new parcel using the parcel traverse, the end or final traverse point might not exactly match the starting point. The parcel then has a misclose or a parcel traverse closure. Large parcel closures indicate incorrect dimensions in the parcel traverse. When entering parcels using the parcel fabric traverse, parcel closure is displayed at the bottom of the Lines tab of the Parcel Details dialog box.

A parcel traverse in the parcel fabric can be adjusted to eliminate a closure. You can specify which adjustment method to use under the Closure tab on the Parcel Details dialog box. There are three adjustment closure methods that you can choose from:

• The compass adjustment
• The Transit adjustment
• The Crandall adjustment

The compass correction technique specifies that the misclosure, or difference in x and y between the resulting endpoint and the desired endpoint, are equally distributed among the individual two-point arcs and curves that make up the traverse. This is done by adjusting the location and distance of each arc proportional to the difference in closure. The compass correction technique is the technique most often used to resolve errors in misclosure. It assumes that the errors are related to both errors in the direction measurements as well as the distance measurements. Thus, the corrections are reflected in each distance and direction value. This technique is also known as the Bowditch rule.

Much like the compass correction technique, the transit correction method specifies that the misclosure is equally distributed among the individual two-point arcs and curves that make up the traverse. However, this technique favors the direction measurements over the distance measurements. In determining the location change required of each arc, the proportion assigned to each arc is proportional to the total x or y values of all the arcs. This results in changes that will affect both the direction and the distance of each arc but will alter the distance to a greater extent.

The Crandall correction technique is used when the direction values are assumed to be precise and accurate, and any misclosure is due solely to errors in distance measurements. This adjustment will preserve all the direction measurements and will alter only the distance measurements to eliminate the closure error. Since directions are fixed, the Crandall adjustment can result in unexpected results, such as flipped directions, very long distance adjustments, or no adjustment at all. Use an alternative method in these cases.

Tip:

You can also set the adjustment method that will always be used by default under the Adjustments tab on the Parcel Editor Options dialog box.

Once you have completed a closed loop parcel traverse, you can click the View closure button on the Parcel Details dialog box to view the parcel closure graphically in the edit sketch of the parcel.

Assigning start and end coordinates

Under the Closure tab you can assign a start coordinate to your parcel traverse. If you are creating an unclosed parcel, you can assign an end coordinate to your traverse. Coordinates can be assigned by snapping to existing features on the map or by manually typing in x,y values. To obtain coordinates by snapping to an existing feature, click the button with the mouse cursor and crosshairs and snap to the point or vertex of the feature on the map. To manually type x,y values, click the Edit button.

If you are working with a closed loop parcel traverse, the end coordinates text box and Compute button are not available. The end coordinate is the same as the specified start coordinate. Once the start coordinate is assigned, click the Lines tab to enter your traverse dimensions. The traverse is closed onto the start coordinates based on a tolerance or using an *.

To assign start and end coordinates to an unclosed parcel traverse, set the value of the Unclosed attribute on the Properties tab of the Parcel Details dialog box to True. Once this attribute is set to true, the end coordinates text box and Compute button becomes available. Once the start and end coordinates are assigned, click the Lines tab to enter your traverse dimensions. To close the traverse onto the end coordinate, click Compute. Any misclose between the traverse end point and the assigned end coordinate will be adjusted through the traverse using the specified closure method.