Resolve Crossing Breaklines in Civil 3D

Bryant Quinney | Senior Applications Expert

During surface creation and modeling within Autodesk Civil 3D, breaklines can sometimes cross each other, possibly preventing the correct surface representation. This may also occur in the data acquisition step in the field. To correct this issue, navigate to the surface contextual ribbon and click Resolve Crossing Breaklines.

You are prompted to choose from 3 options (like other command options, the underlined letter corresponds to typing the letter rather than clicking to choose):

• Survey Database: Assesses crossing breaklines found within the survey database
• Figure: Resolves (only) figures that are present within the surface definition
• Surface: Looks within the surface for any crossing breakline issues

There are some things to consider as to which choice you will make. Think of how the order of data flows:

• The survey database contains the original data that builds the figures (breaklines and point data)
• Figures are queried from the database into the drawing, then used to build a surface
• The surface may contain figures or manual breakline geometry that is not included in the survey database

So, with that in mind, if a user modifies breaklines in the surface (current drawing), other users will only be able to make use of those changes if they receive a data shortcut to that surface. If any figures are later queried from the database, the original issue will still be there. This is the same for figures that are queried into the drawing and used to make the surface. If the resolution of crossing breaklines is done with the Survey Database option, then anyone querying the figures will receive the corrected/modified figures as breakline data. However, if a user has defined breakline data at the surface level, those changes do not populate the database at all, unless specifically added to it.

• If the Survey Database option is chosen, the survey database must first be open for editing. The figures contained are analyzed for crossing issues and reported in the breakline vista.
• With the Figures option selected, the figures that appear in the current drawing are assessed as to any crossing breakline instances.
• When the Surface option is used, the entire surface is assessed for any conflicts with breaklines, no matter the object type (figures, polylines, etc.). If any instances are found, the breakline vista will show in the panorama.

The vista reports information such as the breakline set that each breakline belongs to, the coordinates of the conflict and the elevation difference between the two at that location. To get a visual idea of the issue, click ‘Zoom To’ on the right side and the drawing will center the view on the coordinate location. If AutoZoom is enabled, highlighting the issue in the list will automatically zoom to the location. Once there, you will be shown the pair of breaklines highlighted in color: blue for the higher elevation and red for the breakline with the lower elevation at the conflict point.

To resolve an issue that is related to an elevation conflict, choose an option from the Crossing Resolution pull-down that you would like to use. The first 3 options (use higher elevation, use lower elevation, use average elevation) report the value to be applied, grayed out on the next line. Otherwise, you can specify an elevation to use at this location, in which the entry box will enable you to type in a value to be applied. Click Resolve to apply your decision to the conflict.

To resolve issues that relate to the object length, use the Trim option. This allows the removal of overlapping breaklines. Click Trim and follow the prompts for the choice of trimming an edge to the higher or lower value. A vertex is added to the object that serves as the cutting plane (as shown).

Note: If a 2D line served as the breakline, modifications may not be applied, only reported as conflicts.

Another object modification may be applied by pressing the Gap button. What that means is a segment of your breakline will be removed completely by creating a ‘gap’ back to the last vertex. So, for a single segment that has only the two endpoints, the object is deleted completely if it is ‘gapped’. For a breakline that has more than one segment, the segment that crosses the conflict point is removed from the object, fully removing the issue.

Once you click on the Gap button, you are prompted to select which object to ‘gap’, the higher- or lower-value breakline. There is nothing further to click on as the object is automatically modified.