Data Description and Creation

To support this effort, the GIS Unit of the North Carolina Department of Information Technology–Transportation (NCDIT-T) developed a process to convert the original DGN/CAD files into GIS format. The MergedROWMSUtilities_WFL1 service is sourced directly from the data created through this process.

Within the original data structure, utilities were classified as either “existing” or “proposed.”

• Existing utilities represented conditions at the time the design file was submitted.
• Proposed utilities reflected potential modifications or new infrastructure related to planned DOT roadway projects at the time the design file was submitted.

Existing utilities and proposed utilities were combined into one dataset with the distinction preserved in the dataset’s ROWMSStatus field.

It is important to note that these layers should not be considered authoritative or fully accurate. They are provided as a reference to help identify potential utility conflicts that may require further investigation. Users should confirm the data by consulting other reliable sources (such as utility provider datasets) and through field verification.

Utilities included in this service consist of gas, power, sewer, stormwater, phone, television, and water infrastructure.

To improve usability, additional cleanup and restructuring were applied to the ROWMS data; the next section outlines the step-by-step process used to create the finished utilities feature classes that are part of this service.

Layer Cleanup Steps

Polylines

1. Data copied from source gdb to new database.
2. Fields added for LetDate, AssoCADAnno, and LocationAccuracy.
3. ProjectID and LetDate table joined to feature class on ProjectID field.
4. LetDate value calculated.
5. Join removed.
6. Spatial join used to calculate TextString values from annotation layers to AssoCADAnno field.
7. LocationAccuracy field calculated to “Unknown”. Field is designed to capture confidence in the location of the feature.
8. Lines dissolved, retaining all attributes. 
9. Features split using the Feature to Line tool. The dissolve followed by the split standardized feature geometries so that duplicate features could be identified.
10. Duplicate features identified. Where duplicates existed, the feature with the most recent LetDate was retained.
11. Structure features split from Pipe/Line features based on the LevelName field. (See “Additional cleanup” section below for the geoprocessing steps for the structures layers created from the linear utility layers.)
12. Used the shape length field to identify potential arrow shapes that were incorrectly captured in the utility layers. Manually reviewed and deleted in both existing and proposed utility layers. 
13. AssoCADAnno field values reviewed and invalid values deleted. “Invalid” features defined as annotations not related to pipes (e.g. “Manhole”), text and symbols that are not words or otherwise decipherable (e.g. “Ž•­mC¾Ý?”), and numbers that do not have an apparent relationship to the data, that is, they are too large to represent pipe diameters and have no other information that suggests they are slopes, pipe diameters, or elevations (e.g. “9090”.)
14. CAD-related field removed:
    1. IgdsClass  
    2. IgdsStyle  
    3. IgdsWeight
    4. IgdsColor
    5. IgdsGraphicGroup
    6. IgdsLevel
15. Features outside North Carolina deleted.
16. A new field was added to each feature class for ROWMSStatus and the values “Existing” or “Proposed” were calculated into each field respective to the source feature class. The feature classes were then merged to create the final feature class for each type of utility. 

Additional cleanup done on the “Structure” layers derived from the polyline feature classes

1. Used the feature to polygon tool to create polygons from lines
2. Deleted identical
3. For water features did the following:
   1. Used Select by Attribute “Shape_Area > 16 And Shape_Area < 17.3” to identify potential meters. 
   2. Used Select by Attribute “Shape_Length > 13.3 And Shape_Length < 13.4” to identify potential valves.
4. For sewer features did the following:
   1. Used the ratio of the area of a circle to its circumference (which is r/2) to identify features that are circles and coded them as Type “manhole”.
5. Converted polygons to points.
6. AssoCADAnno field values reviewed and invalid values deleted. “Invalid” features defined as annotations not related to structures (e.g. “6 inch PVC”), text and symbols that are not words or otherwise decipherable (e.g. “Ž•­mC¾Ý?”), and numbers that do not have an apparent relationship to the data, that is, they are too large to represent structure diameters and have no other information that suggests they are elevations, depths, etc. (e.g. “9090”.)
7. CAD-related field removed:
   1. IgdsClass  
   2. IgdsStyle  
   3. IgdsWeight
   4. IgdsColor
   5. IgdsGraphicGroup
   6. IgdsLevel
8. Features outside North Carolina deleted.

Polygons

1. Data copied from source gdb to new database.
2. Fields added for LetDate, AssoCADAnno, and LocationAccuracy.
3. ProjectID and LetDate table joined to feature class on ProjectID field.
4. LetDate value calculated.
5. Join removed.
6. Spatial join used to calculate TextString values from annotation layers to AssoCADAnno field.
7. LocationAccuracy field calculated to “Unknown”. Field is designed to capture confidence in the location of the feature.
8. Duplicate features identified. Where duplicates existed, feature with the most recent LetDate was retained.
9. For sewer features used the ratio of the area of a circle to its circumference (which is r/2) to identify features that are circles and coded them as Type “manhole”.
10. Select by Location used to identify polygons not already captured in the structures feature classes created from the polylines. 
11. Converted selected features to points.
12. AssoCADAnno field values reviewed and invalid values deleted. “Invalid” features defined as annotations not related to structures (e.g. “6 inch PVC”), text and symbols that are not words or otherwise decipherable (e.g. “Ž•­mC¾Ý?”), and numbers that do not have an apparent relationship to the data, that is, they are too large to represent structure diameters and have no other information that suggests they are elevations, depths, etc. (e.g. “9090”.)
13. CAD-related field removed:

14. IgdsClass

15. IgdsStyle

16. IgdsWeight

17. IgdsColor

18. IgdsGraphicGroup

19. IgdsLevel

20. Features outside North Carolina deleted.
21. Appended new features into the appropriate structure layers.
22. A new field was added to each feature class for ROWMSStatus and the values “Existing” or “Proposed” were calculated into each field respective to the source feature class. The feature classes were then merged to create the final feature class for each type of utility.