1. (a) ACF feature type.

   1. (1) Vector lines shall be used to represent centerlines.
   2. (2) The ACF shall seamlessly match across jurisdiction boundaries, i.e., cities, counties, etc.
   3. (3) Address ranges shall be organized along the linear feature to support address geocoding.
   4. (4) The address ranges shall be stored within the centerline attribute table of the geospatial dataset.

2. (b) Topology.

   1. (1) The centerline file shall be processed using appropriate GIS procedures to create and maintain accurate topology, if intended for incorporation into the ACF program.
   2. (2) In order to eliminate common dangle and intersect topological errors, care should be taken while digitizing to snap the endpoints of line centerline segments to endpoints of other line segments.
   3. (3) At a minimum, the following topology rules should be adhered to:

      Topology rule	Rule description	Examples
      Must Not Overlap	Requires that lines not overlap with lines in the same feature class (or subtype). This rule is used where line segments should not be duplicated, for example, in a stream feature class. Lines can cross or intersect but cannot share segments.
      Must Not Intersect	Requires that line features from the same feature class (or subtype) not cross or overlap each other. Lines can share endpoints. This rule is used in cases where the intersection of lines should only occur at endpoints, such as street segments and intersections. Exception would be a grade separated intersection of two streets at an overpass or underpass.
      Must Not Have Dangles	Requires that a line feature must touch lines from the same feature class (or subtype) at both endpoints. An endpoint that is not connected to another line is called a dangle. This rule is used when line features must form closed loops, such as when they are defining the boundaries of polygon features. It may also be used in cases where lines typically connect to other lines, as with streets. In this case, exceptions can be used where the rule is occasionally violated, as with cul-de-sac ordead-end street segments.
      Must Not Intersect Or Touch Interior	Requires that a line in one feature class (or subtype) must only touch other lines of the same feature class (or subtype) at endpoints. Any line segment in which features overlap or any intersection not at an endpoint is an error. This rule is useful where lines must only be connected at endpoints, such as in the case of lot lines, which must split (only connect to the endpoints of) back lot lines and cannotoverlap each other.
      Must Not Self Overlap	Requires that line features not overlap themselves. They can cross or touch themselves but must not have coincident segments. This rule is useful for features, such as streets, where segments might touch in a loop but where the same street should not follow the same course twice.	The individual line feature overlaps itself, with the error indicated by the coral line.
      Must Not Self Intersect	Requires that line features not cross or overlap themselves. This rule is useful for lines, such as contour lines, that cannot cross themselves.
      Must Be Single Part	Requires that lines have only one part. This rule is useful where line features, such as highways, may not have multiple parts.	Multipart lines are created from a single sketch.

      *Topology rules excerpted from http://resources.esri.com.

3. (c) Inclusion of specific geometric elements.

   1. (1) In order to support the development and ongoing maintenance of the public roads linear referencing system, otherwise known as the All Roads Network of Linear Referenced Data (ARNOLD), see http://www.fhwa.dot.gov/policyinformation/hpms/arnold.cfm, geometric elements representing particular road design types should be digitized in the ACF vector layer.

   2. (2) Practices for digitizing these elements can be found in subsection (d) of this section:

      1. (A) Dual carriageway routes;
      2. (B) Single carriageway;
      3. (C) Connector segments;
      4. (D) Traffic circles;
      5. (E) Grade separated access ramps;
      6. (F) At-grade access ramps;
      7. (G) Frontage roads; and
      8. (H) Highway facilities.

4. (d) Digitizing.

   1. (1) Centerline files intended for incorporation into the ACF program may be produced utilizing heads-up digitizing techniques.

   2. (2) Heads-up digitizing methodologies used may include, but are not limited to:

      1. (A) Point mode;
      2. (B) Stream mode;
      3. (C) Spaghetti mode; or
      4. (D) Increment mode.

   3. (3) Heads-up digitizing should be performed utilizing the following standards:

      1. (A) Capture scale should be one to one thousand two hundred (1:1,200);
      2. (B) Projection – UTM Zone 15;
      3. (C) Datum – North American Datum 1983 (NAD83);
      4. (D) Units – Meters; and
      5. (E)
5. (i)
6. (a) (a) Source.

7. (b) (b) At a minimum, the second Generation Digital Ortho Quarter Quadrangles (DOQQs) that have verified horizontal accuracies should be used.

   1. (ii) However, the best available imagery should always be used given that many jurisdictions have acquired their own aerial imagery since the acquisition of the state DOQQs mentioned above.

   2. (4)

      1. (A) Best practices should always be adhered to when digitizing features in the ACF vector layer.

      2. (B) These shall include, but may not be limited to the following:

         1. (i)
8. (a) (a) All linear road features representing public or private roads that have been given a name and left/right range values for addressing purposes should be properly segmented into individual features at intersections representing traffic transportation decision points and snapped to endpoints to ensure proper topology.

9. (b) (b) If an existing road feature is split to create proper segmentation, the left and right addresses ranges should be recalculated to reflect the change in geometry.

   1. (c) (c) The exceptions to this would be but are not limited to:
   2. (1) (1) Where the local jurisdiction digitizes driveways for location purposes and does not name or range them for addressing; and

   3. (2)

      1. (A) (2)(A) Where two (2) road centerline features intersect and do not represent a transportation decision point, e.g., an overpass or underpass where direct travel between the roads is not possible.

      2. (B) (B) Centerlines should not split (segmented) at these locations;

         1. (ii)
10. (a) (a) When digitizing curves, utilize the minimum number of vertices that will accurately represent the true shape of the road.

11. (b) (b) However, use of arc/node, Bezier curve, or tangent curve tools is not recommended due to the excessive number of vertices the tools create;

    1. (iii)
12. (a) (a) For single carriageway roads, the actual centerline of the traversable lanes should be digitized.

13. (b) (b) This also applies to:

    1. (1) (1) Connector segments;
    2. (2) (2) Grade separated access ramps;
    3. (3) (3) At-grade access ramps;
    4. (4) (4) Traffic circles;
    5. (5) (5) Frontage roads; and

    6. (6) (6) Highway facilities.

       1. (c) (c) Single carriageway roads should be digitized in the direction of increasing address range values as prescribed by the local addressing authority.

          1. (d) (d) All one-way access ramps should be digitized in the direction of vehicular travel; and
          2. (iv)
14. (a) (a) For dual carriageway roads, separate linear features should be digitized along the actual centerline of each set of traversable lanes separated by the positive barrier or median.

15. (b) (b) All access ramps should be included.

    1. (c) (c) Centerlines should be digitized in the direction of travel and left/right range values created in such a way to enable proper geocoding in the antilog direction.

16. (e) Edge matching.

    1. (1) Where roads cross political boundaries, e.g., city, county, or state boundary, the linear centerline feature shall be snapped to the edge of the applicable boundary and properly segmented.
    2. (2) The city, county, and state boundaries maintained by the Arkansas Department of Transportation and the Arkansas Geographic Information Systems Office and available via gis.arkansas.gov should be used as the geometric features to which the road segments are snapped.
    3. (3) Where a road centerline is coincident with a political boundary and different jurisdictions are on each side, e.g., a city and a county, a single centerline feature should be used and differences in naming and addressing practices attributable to the different jurisdictions should be accounted for by using the alternate fields.
17. (f) Global Navigation Satellite System (GNSS). Centerline files intended for incorporation into the ACF program may be produced utilizing current accepted standards for GNSS data collection.

Codification Notes: "ACF" means Arkansas Centerline File.