The Geo-Validation process

This topic outlines the criteria and logic used by the Geo Validation process to validate address or location information against the geofile. Understanding how the process works will help you to best use the process to ensure the quality of your data. The geo-validation process analyzes the address or location information that has been provided and attempts to determine the best possible means to cross check the geofile. The geofile consists of two basic files that can be used to validate locations. These two files are defined as follows;

Street Segment File

The street segment file is a table that holds information on street segments and their associated attributes. A street segment is a section of a street with two defined end points. The end points are most often other streets. For example; Main Street between 1st Street and 2nd Street would be a street segment. Likewise Main Street between 2nd Street and 3rd Street would be another segment. Each segment has an associated Odd and Even address range and the associated Beat, District and Sector for both the Odd and Even sides of the street segment. By defining multiple segments you pre-define the proper geographic references for all locations within a defined area.

Premise File

The premise file is actually a discrete address file. This file hold information about actual pre-defined addresses and locations. One or more premise records can be linked to Segment record, as a premise address can fall within the boundaries of a segment.

The Validation Algorithm

The geo-validation process first examines and address or common place name to see how much information it has to work with. The more information provided the more exact the geofile match or ‘hit’ will be, likewise the more information provided the greater the possibility that no match will be found due to a discrepancy in the data provided compared to the pre-defined geofile. Example: You jurisdiction my have a ‘Main Avenue’ and the street segment file reflects ‘Main Avenue’ as it should. However, often this is referred to as ‘Main Street’. The geo-validation process attempts to resolve these issues whenever possible.

The validation process first checks to see if it has a street name. If not, it looks for a common place name. If a street name is found it then looks to see if it has other street location identifiers, such as street type, street prefix, street suffix and street digits.

If it has street digits it will check the premise file for an exact match on the location. If no exact match can be made it then checks the street segment file and attempts to locate a street segment that encompasses the street location specified.