How Thin Road Network works

About Thin Road Network

The Thin Road Network tool compiles a simplified collection of roads by identifying segments that can be removed from the display without affecting the general character, density, and overall connectivity of the roads. Features that do not participate in the resulting road collection are identified by an attribute on the input layers that can be used in a definition query or in a selection to create a new layer.

Features are not actually deleted by Thin Road Network. To actually remove features, consider using the Trim Line tool.

The degree of road collection thinning is controlled by the Minimum Length parameter. The morphology and character of the road network should be considered. Typically, regular road patterns that include gridded areas, such as those common in North American cities, require a larger minimum length than more organically shaped road collections.

Use the following table as a guideline for values in map units to use with this parameter with different output scales. Refine these values as necessary to achieve desired results.

Organic, nongridded road patterns

Regular, gridded road patterns

Final scale

Map units

Page units

Map units

Page units

1:25,000

250 m

825 ft.

1 cm

500 m

1,650 ft.

2 cm

1:50,000

500 m

1,650 ft.

1 cm

1,000 m

3,300 ft.

2 cm

1:100,000

1,000 m

3,300 ft.

1 cm

2,000 m

6,600 ft.

2 cm

1:250,000

2,500 m

8,250 ft.

1 cm

5,000 m

16,500 ft.

2 cm

1:500,000

5,000 m

16,500 ft.

1 cm

10,000 m

33,000 ft.

2 cm

Data preparation considerations

Multiple road layers can be assessed simultaneously to ensure that all classes of roads are considered in the final display. This tool is optimized for the spatial relationships typically found in a road network. Unexpected results may be produced if the tool is used to process other themes. It is very important that the geometry of the input features is correctly established for the tool to maintain the relationship of the features as they coexist in a road collection. Take note of the following input data requirements and suggestions:

CautionCaution:

A warning is raised if the input features are not in a projected coordinate system. This tool relies on linear distance units, which will create unexpected results in an unprojected coordinate system. It is strongly suggested that you run this tool on data in a projected coordinate system to ensure valid results. An error is raised and the tool will not process if the coordinate system is missing or unknown.

Workflow considerations

This tool is generally most effective when used in conjunction with other generalization and graphic conflict resolution tools. Here are some tips to help you use these tools together with other layers and other tools in a workflow:

Partitioning large datasets

This tool acts contextually such that adjacent and connecting features are considered when determining the final state of each individual feature. Multiple datasets can be input at once, which means they are all considered simultaneously. Using a large amount of input data (or many separate input layers) can exceed memory limitations. To avoid this limitation, consider enabling partitioning when running this tool by specifying a partition feature class in the Cartographic Partitions geoprocessing environment variable. Partitioning allows the tool to sequentially process the data in logical and manageable chunks. The input features delineated by each partition polygon is loaded into the tool, along with additional data from a buffer zone surrounding the partition. The additional data is considered as processing proceeds. This ensures that the resulting feature classes are seamless and the states of features spanning across partition boundaries are consistent.

When processing by partition, it is possible that roads that cross partition boundaries may be flagged by two adjacent partitions with conflicting results in the Invisibility Field. In order to identify areas of conflict like this, add a field called TRN_DIFF to the input feature classes prior to processing. When defining the Invisibility Field for each partition, the tool will determine if the field is not empty and the new proposed value does not equal the populated value. In this case, a conflict has occurred, and the TRN_DIFF field will be populated with a 1.

Related Topics

3/3/2014