Sidewalk and Trail Centerline Features of Loudoun County, VA (2015)
Metadata also available as
Metadata:
- Identification_Information:
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- Citation:
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- Citation_Information:
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- Originator:
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Loudoun County, VA, Office of Mapping and Geographic Information (OMAGI)
- Publication_Date: 20141222
- Title:
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Sidewalk and Trail Centerline Features of Loudoun County, VA (2015)
- Geospatial_Data_Presentation_Form: vector digital data
- Online_Linkage: <http://www.loudoun.gov/Default.aspx?tabid=325>
- Description:
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- Abstract:
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Sidewalk and Trail Centerlines are a layer derived from the base map data layer Miscarc_line as well as from aerial imagery. Miscarc_line is a base map data layer derived by automated processes and processed for cartographic representation at 1:2400 scale. Typical features captured in Miscarc_lines are sidewalks, trails, shared use paths, and the W&OD trail features as seen from above and are mapped to National Map Accuracy Standards (NMAS). Crosswalks are captured from visual inspection and digitization from the County's digital aerial imagery.
- Purpose:
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Sidewalk, Shared Use Path, and Trail Centerlines are used as cartographic elements indicating features not commonly captured. General Services, Parks & Recreation, or Planning may be primary users of Sidewalk and Trail Centerline features.
- Supplemental_Information:
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Loudoun County has been maintaining Base map data layers since 1980. Ground features are captured and attributed throught the base map maintenance services contract kept by the County. A complete, Countywide remapping project, conducted in two phases, and corresponding updates have yielded the current data set. Phase I, using 2002 Virginia Base Mapping Program (VBMP) digital scanned imagery, and Phase II, using 2004 scanned aerial photography comprise the initial re-map effort. See "Source_Contribution:" for extent of Phase areas. The project was completed in 2005 and now undergoes annual updates, with the next one occurring in Spring 2008. Many annual cycles (2005 to present) of base map update contribute to the development of this layer. OMAGI updates all base map data selectively according to development patterns through stereocompilation and photogrammetry; therefore some feature data may not be current. After years of selective updates based on development, the result was an eastern, suburban part of the County that was updated almost yearly, and a western, rural part of the County that changed little year to year and missed out on the yearly update. As a result, Loudoun County is on a three year update cycle, 1/3rd of the County each year. A generalized map of the update years can be located at OMAGI's documents page under Basemaps. Data are stored in the corporate ArcSDE Geodatabase as a line feature class. The coordinate system is Virginia State Plane (North), Zone 4501, datum NAD83 HARN, Vertical datum, NAVD88 , US Survey foot units.
- Time_Period_of_Content:
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- Time_Period_Information:
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- Range_of_Dates/Times:
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- Beginning_Date: 20080428
- Ending_Date: 20120430
- Currentness_Reference: Layer contains features found on aerial imagery up to 2012
- Status:
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- Progress: Complete
- Maintenance_and_Update_Frequency: As needed
- Spatial_Domain:
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- Bounding_Coordinates:
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- West_Bounding_Coordinate: -77.891085
- East_Bounding_Coordinate: -77.325717
- North_Bounding_Coordinate: 39.322249
- South_Bounding_Coordinate: 38.848914
- Keywords:
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- Theme:
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- Theme_Keyword_Thesaurus: User generated keywords
- Theme_Keyword: golf path
- Theme_Keyword: shared use path
- Theme_Keyword: sidewalk
- Theme_Keyword: crosswalk
- Theme_Keyword: W&OD
- Theme_Keyword: trail
- Theme:
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- Theme_Keyword_Thesaurus: ISO 19115 Topic Categories
- Theme_Keyword: society
- Theme:
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- Theme_Keyword_Thesaurus: ISO 19115 Topic Categories
- Theme_Keyword: society
- Place:
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- Place_Keyword_Thesaurus: User generated keywords
- Place_Keyword: Virginia
- Place_Keyword: County
- Place_Keyword: Loudoun
- Access_Constraints: None
- Use_Constraints:
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These data were generated for use by Loudoun County and are available to the public. These data are intended for use at 1:2400 scale or smaller. Acknowledgement of Loudoun County would be appreciated in products derived from this data.
- Point_of_Contact:
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- Contact_Information:
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- Contact_Organization_Primary:
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- Contact_Organization: Loudoun County, VA, OMAGI
- Contact_Position: Base Map Cartographer
- Contact_Address:
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- Address_Type: mailing and physical
- Address: P.O. Box 7000
- Address: 1 Harrison Street SE, 2nd Floor
- City: Leesburg
- State_or_Province: VA
- Postal_Code: 20177-7000
- Country: US
- Contact_Voice_Telephone: (703)771-5778
- Contact_Facsimile_Telephone: (703)771-5075
- Contact_Electronic_Mail_Address: mapping@loudoun.gov
- Hours_of_Service: 8:00-5:00 EST, M-F
- Native_Data_Set_Environment: Version 6.2 (Build 9200) ; Esri ArcGIS 10.2.2.3552
- Data_Quality_Information:
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- Attribute_Accuracy:
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- Attribute_Accuracy_Report:
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Sidewalk and Trail Centerlines have undergone extensive Quality Assurance procedures to ensure feature attribution is consistent with the data dictionary and adheres to a logical relationship with neighboring features and layers.
- Quantitative_Attribute_Accuracy_Assessment:
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- Attribute_Accuracy_Value: >90% attribute accuracy exists
- Attribute_Accuracy_Explanation:
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27 separate block study areas underwent QA/QC comparison with the source orthophoto and overlaying base map layers. Greater than 90% of all features in each block achieve correct TYPE attribution. OMAGI compiled a separate PGDB for known attribute errors above 90% threshold.
- Logical_Consistency_Report: Topologically clean
- Completeness_Report:
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Base Map features have been updated from different sources and in different years. Although the entire county was originally mapped, users should be cautious and aware that any particular area of interest may not be absolutely current and up to date. A generalized map of update years can be located at the OMAGI's webpage. The next anticipated update shall occur using 2008 imagery.
- Positional_Accuracy:
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- Horizontal_Positional_Accuracy:
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- Horizontal_Positional_Accuracy_Report:
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A random sampling method was utilized to locate thirty points each over the Phase I (2002 data) and Phase II (2004 data) Project areas to be used in the accuracy assessment. Once the random points were visually located on the digital maps a survey crew was dispatched to obtain GPS coordinates of these points. From the thirty points randomly selected, each point was surveyed using Ashtech Z-12 dual frequency GPS receivers in static mode in a geodetic network format as specified in the FGCS Guidelines. GPS Raw data was processed with the Ashtech Office Suite (AOS) data reduction software. This provided the location of the reference data for the accuracy assessment calculations. Utilizing the sketches, Northing , Easting and Elevations of each of the points were measured by a stereocompilation technician. The photogrammetrically determined values are coincident with the final coordinate values in the digital data. To complete the NSSDA (National Standard for Spatial Data Accuracy) accuracy assessment the two measurements are compared and a circular root mean square error (RMSE) is calculated. A spreadsheet was prepared with the measurements and results of these points. In Phase 1 ( 2002 ) 25 points in Western Loudoun were considered for Accuracy Assessment. In Phase II ( 2004) 23 points in Eastern Loudoun were considered for Accuracy Assessment. In Phase III (2005 ) features were compiled to meet ASPRS and NSSDA standards for Class I map at 1:2400 scale, but a rigid accuracy test was not performed. In Phase IV ( 2007 ) 23 points were considered for Accuracy Assessment. These calculations were made according to Chapter 3, National Standard for Spatial Data Accuracy, Geospatial Positioning Accuracy Standards, FGDC-STD-007.3-1998: Washington, D.C., Federal Geographic Data Committee, 1998, 28 p. The report can be downloaded from <http://www.fgdc.gov/standards/projects/FGDC-standards-projects/accuracy/part3/chapter3> Accuracy measures described below are valid for Phase IV ( 2007 ) data (Accuracy Assessment 1) and then Phase 1 and II (Accuracy Assessment 2).
- Quantitative_Horizontal_Positional_Accuracy_Assessment:
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- Horizontal_Positional_Accuracy_Value: Circular RMSE (E, N): 0.7; Tested 1.3 US Survey feet
- Horizontal_Positional_Accuracy_Explanation:
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Measured at a 95% confidence level, any points measured will be within 1.3 US Survey feet in the horizontal domain.
- Vertical_Positional_Accuracy:
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- Vertical_Positional_Accuracy_Report: Not Available
- Lineage:
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- Source_Information:
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- Type_of_Source_Media: None
- Source_Contribution:
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Loudoun County Miscellaneous Arc Data from 2009 & 2012 Basemap Update contracted for by Loudoun County, VA OMAGI and 2012 digitial aerial imagery to fill in "data gap" of 2009-2012 over the entire County
- Source_Information:
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- Source_Citation:
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- Citation_Information:
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- Publication_Date: 20140203
- Title: GPS data collection
- Type_of_Source_Media: None
- Source_Citation_Abbreviation: GPS data collection
- Source_Contribution:
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GPS collection of two Loudoun County park trail systems and 2012 digital aerial imagery
- Source_Information:
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- Source_Citation:
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- Citation_Information:
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- Originator: Loudoun County, VA, OMAGI
- Publication_Date: 20070503
- Title: Base Map Maintenance Services Contract, QQ-00986, Phase IV
- Source_Scale_Denominator: 2400
- Type_of_Source_Media: None
- Source_Citation_Abbreviation: Base Map Maintenance Services Contract, QQ-00986, Phase IV
- Source_Contribution:
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Loudoun County Miscellaneous Arc Data from 2008 Basemap Update contracted for by Loudoun County, VA OMAGI and 2008 digitial aerial imagery
- Process_Step:
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- Process_Description:
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Sidewalks, Trails, & Shared Use Paths collected from two different sources: Miscellaneous Arcs & 2008 Aerial photograph. To collect from Miscellaneous Arcs, both sidewalk and trail/shared use path features were exported from the layer. The sidewalk features were orginally the edge of sidewalk lines and changed to a single centerline process through a GIS process. The next step involved using the 2008 aerial photography to capture all missing sidewalk and trail features on a countywide scale. Centerlines of "missing" trails, sidewalk features, and shared use paths were digitized on-screen. All existing crosswalks as of 2008 were also captured with on-screen digitization
- Process_Date: 20111230
- Process_Contact:
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- Contact_Information:
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- Contact_Organization_Primary:
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- Contact_Organization: Loudoun County, VA, OMAGI
- Contact_Position: Base Map Cartographer
- Process_Step:
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- Process_Description:
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Sidewalks and Trails layer updated to primarily include existing trail features in some Loudoun County public parks and properties; including Banshee Reeks Nature Preserve, Bless Park, Claude Moore Park, Franklin Park, Philip A. Bolen Memorial Park. Other "missing" features existing on both the 2012 and 2013 imagery were also collected at random locations thoughout the County.
- Process_Date: 20140217
- Process_Contact:
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- Contact_Information:
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- Contact_Organization_Primary:
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- Contact_Organization: Loudoun County, VA OMAGI
- Process_Step:
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- Process_Description:
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Sidewalks and Trails layer updated to 2012 currentness level with 2009 and 2012 miscellaneous arc data & features digitized from 2012 aerial imagery. This is to fill in the "missing data gap" of 2009 - 2012 in the data. A few more Loudoun County/State park trail features were added from GPS collection by OMAGI staff during summer of 2014 field collection.
- Process_Date: 20140901
- Process_Step:
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- Process_Description:
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Sidewalks and Trails layer updated to 2013 currentness level with 2013 miscellaneous arc data & features digitized from 2013 aerial imagery. This is to continue to update the layer to the currentness of the existing Basemap data.
The existing trail features at Phil Bolen park were added from GPS collection by OMAGI staff during summer of 2015 field collection.
- Process_Date: 20150701
- Process_Contact:
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- Contact_Information:
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- Contact_Organization_Primary:
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- Contact_Organization: Loudoun County, VA OMAGI
- Spatial_Data_Organization_Information:
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- Indirect_Spatial_Reference: Loudoun County
- Direct_Spatial_Reference_Method: Vector
- Point_and_Vector_Object_Information:
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- SDTS_Terms_Description:
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- SDTS_Point_and_Vector_Object_Type: String
- Point_and_Vector_Object_Count: 55387
- Spatial_Reference_Information:
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- Horizontal_Coordinate_System_Definition:
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- Planar:
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- Map_Projection:
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- Map_Projection_Name: NAD 1983 HARN StatePlane Virginia North FIPS 4501 Feet
- Lambert_Conformal_Conic:
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- Standard_Parallel: 38.03333333333333
- Standard_Parallel: 39.2
- Longitude_of_Central_Meridian: -78.5
- Latitude_of_Projection_Origin: 37.66666666666666
- False_Easting: 11482916.66666666
- False_Northing: 6561666.666666666
- Planar_Coordinate_Information:
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- Planar_Coordinate_Encoding_Method: coordinate pair
- Coordinate_Representation:
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- Abscissa_Resolution: 0.00032808333333333333
- Ordinate_Resolution: 0.00032808333333333333
- Planar_Distance_Units: foot_us
- Geodetic_Model:
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- Horizontal_Datum_Name: D North American 1983 HARN
- Ellipsoid_Name: GRS 1980
- Semi-major_Axis: 6378137.0
- Denominator_of_Flattening_Ratio: 298.257222101
- Entity_and_Attribute_Information:
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- Detailed_Description:
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- Entity_Type:
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- Entity_Type_Label: GISDBB.GISBROW.SIDEWALKS_TRAILS_LINE
- Entity_Type_Definition: line feature class
- Entity_Type_Definition_Source: ESRI
- Attribute:
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- Attribute_Label: OBJECTID_1
- Attribute_Definition: Internal feature number.
- Attribute_Definition_Source: Esri
- Attribute_Domain_Values:
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- Unrepresentable_Domain:
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Sequential unique whole numbers that are automatically generated.
- Attribute:
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- Attribute_Label: ROAD_FROM
- Attribute_Definition: Road the feature comes from
- Attribute_Definition_Source: Loudoun County
- Attribute_Domain_Values:
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- Unrepresentable_Domain: User generated street name (NA = unsure of road)
- Attribute:
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- Attribute_Label: ROAD_NAME
- Attribute_Definition: Name of street feature runs along
- Attribute_Definition_Source: Loudoun County
- Attribute_Domain_Values:
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- Unrepresentable_Domain: User generated text
- Attribute:
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- Attribute_Label: SOURCE
- Attribute_Definition: Source of feature collection
- Attribute_Definition_Source: Loudoun County
- Attribute_Domain_Values:
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- Enumerated_Domain:
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- Enumerated_Domain_Value: 1
- Enumerated_Domain_Value_Definition: Miscellaneous Arcs Data Set
- Enumerated_Domain_Value_Definition_Source: Loudoun County
- Enumerated_Domain:
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- Enumerated_Domain_Value: 4
- Enumerated_Domain_Value_Definition: Any other secondary source
- Enumerated_Domain_Value_Definition_Source: Loudoun County
- Enumerated_Domain:
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- Enumerated_Domain_Value: 3
- Enumerated_Domain_Value_Definition: GPS Collected Feature
- Enumerated_Domain_Value_Definition_Source: Loudoun County
- Enumerated_Domain:
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- Enumerated_Domain_Value: 2
- Enumerated_Domain_Value_Definition: Aerial Image & on-screen digitization
- Enumerated_Domain_Value_Definition_Source: Loudoun County
- Attribute:
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- Attribute_Label: CATEGORY
- Attribute_Definition: Type of feature
- Attribute_Definition_Source: Loudoun County
- Attribute_Domain_Values:
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- Enumerated_Domain:
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- Enumerated_Domain_Value: SHARED USE PATH
- Enumerated_Domain_Value_Definition:
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Visible, paved passageway primarily used for pedestrian or bicycle traffic, are typically separated from the roads by landscaping or grassy patches and are non-linear in appearance.
- Enumerated_Domain_Value_Definition_Source: Loudoun County
- Enumerated_Domain:
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- Enumerated_Domain_Value: GOLF PATH
- Enumerated_Domain_Value_Definition:
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Paved golf cart paths on golf courses that are permanent in nature & intended for golf course use only
- Enumerated_Domain_Value_Definition_Source: Loudoun County
- Enumerated_Domain:
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- Enumerated_Domain_Value: CROSSWALK
- Enumerated_Domain_Value_Definition:
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Visible, paved, and marked passageway primarily used for pedestrian or bicycle traffic to cross a road.
- Enumerated_Domain_Value_Definition_Source: Loudoun County
- Enumerated_Domain:
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- Enumerated_Domain_Value: TRAIL
- Enumerated_Domain_Value_Definition:
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Visible, permanent dirt, or gravel passageway primarily used for pedestrian or bicycle traffic; primarily in public parks thoughout County
- Enumerated_Domain_Value_Definition_Source: Loudoun County
- Enumerated_Domain:
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- Enumerated_Domain_Value: SIDEWALK
- Enumerated_Domain_Value_Definition:
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Concrete or asphalt pedestrian walkways directly adjacent or parallel to roads or network through neighborhoods.
- Enumerated_Domain_Value_Definition_Source: Loudoun County
- Enumerated_Domain:
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- Enumerated_Domain_Value: WOD
- Enumerated_Domain_Value_Definition:
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Polygonal trail feature running from Purcellville to Fairfax County boundary that includes both paved bike and criss-crossing unpaved equestiran trails.
- Enumerated_Domain_Value_Definition_Source: Loudoun County
- Attribute:
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- Attribute_Label: SIDE_OF_RO
- Attribute:
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- Attribute_Label: ROAD_TO
- Attribute_Definition: Road the feature goes to
- Attribute_Definition_Source: Loudoun County
- Attribute_Domain_Values:
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- Unrepresentable_Domain: User generated street name (NA = unsure of road)
- Attribute:
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- Attribute_Label: MATERIAL
- Attribute_Definition: Feature material type
- Attribute_Definition_Source: Loudoun County
- Attribute_Domain_Values:
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- Unrepresentable_Domain: User generated text
- Attribute:
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- Attribute_Label: MIN_LANDSC
- Attribute:
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- Attribute_Label: MAX_LANDSC
- Attribute:
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- Attribute_Label: WIDTH
- Attribute_Definition: Feature width in feet
- Attribute_Definition_Source: Loudoun County
- Attribute_Domain_Values:
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- Unrepresentable_Domain: User generated text
- Attribute:
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- Attribute_Label: SUB_CATEGO
- Attribute:
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- Attribute_Label: UPD_DATE
- Attribute_Definition: Date that feature was updated
- Attribute_Definition_Source: Loudoun County
- Attribute_Domain_Values:
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- Unrepresentable_Domain: User generated text
- Attribute:
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- Attribute_Label: LANDSCAPE_
- Attribute:
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- Attribute_Label: PAINT
- Attribute_Definition: Paint type (crosswalks)
- Attribute_Definition_Source: Loudoun County
- Attribute_Domain_Values:
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- Enumerated_Domain:
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- Enumerated_Domain_Value: STRIPED
- Enumerated_Domain_Value_Definition: Crosswalk painted with series of vertical bars
- Enumerated_Domain_Value_Definition_Source: Loudoun County
- Enumerated_Domain:
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- Enumerated_Domain_Value: OUTLINE
- Enumerated_Domain_Value_Definition: Crosswalk with only outside edges painted (Two stripes)
- Enumerated_Domain_Value_Definition_Source: Loudoun County
- Enumerated_Domain:
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- Enumerated_Domain_Value: FILL
- Enumerated_Domain_Value_Definition: Completely painted-in crosswalk (solid white stripe)
- Enumerated_Domain_Value_Definition_Source: Loudoun County
- Enumerated_Domain:
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- Enumerated_Domain_Value: NA
- Enumerated_Domain_Value_Definition: Not applicable (for all other CATEGORY values)
- Attribute:
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- Attribute_Label: OBJECTID
- Attribute_Definition: Internal feature number.
- Attribute_Definition_Source: ESRI
- Attribute_Domain_Values:
-
- Unrepresentable_Domain:
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Sequential unique whole numbers that are automatically generated.
- Attribute:
-
- Attribute_Label: Shape_STLe
- Attribute:
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- Attribute_Label: SHAPE
- Attribute_Definition: Feature geometry.
- Attribute_Definition_Source: ESRI
- Attribute_Domain_Values:
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- Unrepresentable_Domain: Coordinates defining the features.
- Attribute:
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- Attribute_Label: Shape.STLength()
- Distribution_Information:
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- Distributor:
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- Contact_Information:
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- Contact_Organization_Primary:
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- Contact_Organization: Loudoun County, VA, OMAGI
- Contact_Position: Public Information Counter
- Contact_Address:
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- Address_Type: mailing and physical
- Address: 1 Harrison Street SE, 2nd Floor
- Address: P.O. Box 7000
- City: Leesburg
- State_or_Province: VA
- Postal_Code: 20177-7000
- Country: US
- Contact_Voice_Telephone: (703)771-5778
- Contact_Facsimile_Telephone: (703)771-5075
- Contact_Electronic_Mail_Address: mapping@loudoun.gov
- Hours_of_Service: 8:00-5:00 EST, M-F
- Distribution_Liability:
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Every reasonable effort has been made to assure the accuracy of these data. Loudoun County, Virginia does not assume any liability arising from the use of these data. These data are provided without warranty of any kind, expressed or implied, including, but not limited to, the implied warranties of merchantability and fitness for a particular service. Reliance on these data is at the risk of the user.
- Standard_Order_Process:
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- Digital_Form:
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- Digital_Transfer_Information:
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- Format_Name: DXF
- Format_Specification: AutoCad Digital Exchange File
- Digital_Transfer_Option:
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- Offline_Option:
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- Offline_Media: CD-ROM
- Offline_Option:
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- Offline_Media: CD-ROM
- Offline_Option:
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- Offline_Media: CD-ROM
- Fees:
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Loudoun County distributes spatial data in ArcGIS coverage or shapefile format for the cost of reproduction. Countywide spatial datasets may be purchased for $21 per CD or $22 per DVD for up to 650 MB or 4.5 GB of data, respectively. There is a $10 surcharge to purchase countywide topography, and a $3 charge if the item is to be mailed. If the customer wants the data in DXF format and/or would like OMAGI to custom select specific geographic areas of the County, there is an additional $7 per 15 minute increment labor charge. Select aerial imagery is also available.
- Ordering_Instructions:
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Size limit: 640MB. Visit our website at: <http://www.loudoun.gov/omagi/index.htm>, click on "OMAGI Documents and Information." Our "Products & Services" link will lead you to order forms and lists of available data. Hardcopy maps may also be available; please contact the Mapping Office Public Information Counter for more information regarding all data requests.
- Metadata_Reference_Information:
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- Metadata_Date: 20150727
- Metadata_Contact:
-
- Contact_Information:
-
- Contact_Organization_Primary:
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- Contact_Organization: Loudoun County, VA, OMAGI
- Contact_Person: Metadata Specialist
- Contact_Address:
-
- Address_Type: mailing and physical
- Address: MS 65
- Address: 1 Harrison Street SE, 2nd Floor
- City: Leesburg
- State_or_Province: VA
- Postal_Code: 20175
- Contact_Voice_Telephone: (703)771-5778
- Contact_Facsimile_Telephone: (703)771-5075
- Contact_Electronic_Mail_Address: mapping@loudoun.gov
- Hours_of_Service: 8:00-5:00 EST, M-F
- Metadata_Standard_Name: FGDC Content Standard for Digital Geospatial Metadata
- Metadata_Standard_Version: FGDC-STD-001-1998
- Metadata_Time_Convention: local time
- Metadata_Use_Constraints:
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This metadata reflects the source Geodatabase format and specific elements may not apply if your data is exported to SHP, DXF, or .e00 products. User must be aware that changes to data schema occur during data export that may not be reflected in this metadata, which represents Loudoun County's corporate geodatabase. Acknowledgement of Loudoun County would be appreciated in the use of this metadata.
Generated by mp version 2.9.12 on Tue Aug 04 09:48:29 2015