Linear Reference System (LRS)
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      Linear Reference System (LRS) Specification

      A summary of Urban SDK's Linear Reference System (LRS) and the associated metadata specification.

      LRS_Graphic

      1.0 Introduction

      A Linear Reference System (LRS) is a method of spatial referencing that describes the location of roadways from a fixed global point. Urban SDK uses the LRS to tag all data to a common network.

      💡Tip: If you are working with many different types of Urban SDK data, each road segment's unique ID can be used to cross-reference or join information between different datasets.

      2.0 Data Specification

      The following fields are metadata referenced through the LRS, and which are included as fields in all of Urban SDK's data:

      Field Type Description
      road_segment_id integer Unique ID for each segment of road.
      road_name string The name of the roadway. It will be null if the data is not provided in the LRS.
      county string The name of the county the segment resides within. It will be null if the link does not reside within a county.
      state string The State or Province that the segment resides within.
      funclass_id integer

      The road function class of the segment:

      1. Class 1 - Interstate
      2. Class 2 - Highway
      3. Class 3 - State Road
      4. Class 4 - Arterial
      5. Class 5 - Local
      road_segment_length numeric The road segment length, in miles.
      geometry string The line string geometry for the segment, provided in well-known text (WKT) format.
      speed_category integer Estimated based on road functional class and observed average speeds (in mph); it is intended to provide an estimate of what a reasonable speed limit would be on a road, within +/- 5mph.

      💡Tip - The WKT is for importing into GIS software: Well-Known Text (WKT) is a text markup language used for representing vector geometry objects, spatial reference systems of spatial objects, and transformations between spatial reference systems.  This is how the Linear Reference System (LRS) geometry is able to be interpreted by most GIS software. Every file provided by Urban SDK has a geometry field with the WKT data necessary to visualize and convert to other spatial formats in GIS software.

      💡Tip - Metadata can be used for filtering: The metadata provided within the LRS makes it's easy to filter, disaggregate, or aggregate data. For instance, if data is obtained across a region, customers can filter data based on County, or alternatively, filter data based on road name, or functional class.  Segment length also makes it possible to quantify centerline miles of roadway.