Collapse Dual Lines To Centerline (Data Management) (ArcInfo only)

Usage tips

• This tool is designed to work with fairly regular, near parallel pairs of lines, such as large-scale road casings. Centerlines will be created only between open-ended lines, not inside closed lines which are likely street blocks.

• Centerlines will be derived based on the specified width parameters. A dual-line feature wider than the Maximum Width or narrower than the Minimum Width will not be centerlined. Use known road widths if available. However, since casings usually become wider at intersections, set the Maximum Width slightly greater than the known maximum width. You may need to experiment to find suitable parameters.

• The output feature class will not carry the geographic attributes from the input lines, but contain the following three new fields:

  • LnType — Contains the following line type values:
  • value of 1 for derived centerlines
  • value of 2 for outlines around relatively complicated intersections where centerlines are not generated, lines representing roads with a width beyond the specified range, and other broken or unpaired lines.
  • value of 3 for lines with unclear source casings (they usually connect two closely located intersections which may belong to one large intersection in reality.)
  
  
  • LeftLn_FID — Carries the object ID of the input line to the left of a derived centerline. This field value will be zero for lines of LnType 2 and 3.
  • RightLn_FID — Carries the object ID of the input line to the right of a derived centerline. This field value will be zero for lines of LnType 2 and 3.

  You can use the LnType values to further inspect the unresolved intersections and wider roads; and you can use the LeftLn_FID and RightLn_FID fields and other geoprocessing tools to transfer the attributes as needed.

• Since the tool is not designed for natural features, such as irregularly shaped double-line rivers, you may get unexpected results if you apply it to such features. The tool may also produce unexpected results if you apply it to relatively smaller-scale road data, such as multiple-lane highways with interchanges, ramps, overpasses and underpasses, or railways with multiple, merging tracks.

• Learn more about spatial reference and geoprocessing

• The following environment settings affect this tool: XY tolerance, Extent, M domain, Coordinate system, Output has M values, Output has Z values, Default Z value, Output XY domain, workspace, and scratch workspace.

Command line syntax
An overview of the Command Line window
CollapseDualLinesToCenterline_management <in_features> <out_feature_class> <maximum_width> {minimum_width}

Command line example

collapseduallinestocenterline_management c:\mapData.mdb\roads c:\mapDataNew\centerlines 100 0

Scripting syntax
About getting started with writing geoprocessing scripts
CollapseDualLinesToCenterline_management (in_features, out_feature_class, maximum_width, minimum_width)

Script example

import arcgisscripting
gp = arcgisscripting.create()

gp.workspace = "h:\\workspace"
gp.toolbox = "management"
gp.collapseduallinestocenterline ("roads", "centerlines", "100")