Sidewalk and Trails of Loudoun County, VA (2023)

Metadata:

• Identification_Information
• Data_Quality_Information
• Spatial_Data_Organization_Information
• Spatial_Reference_Information
• Entity_and_Attribute_Information
• Distribution_Information
• Metadata_Reference_Information

Identification_Information:

Citation:

Citation_Information:

Originator:

Loudoun County, VA, Office of Mapping and Geographic Information (OMAGI)

Publication_Date: 20240824

Title: Sidewalk and Trails of Loudoun County, VA (2023)

Geospatial_Data_Presentation_Form: vector digital data

Online_Linkage: see distribution information

Description:

Abstract:

Sidewalks and trails are a base map data layer derived by automated and manual processes and processed for cartographic representation at 1:2400 scale. These line features represent the centerline of sidewalks and trails as seen from above and are mapped to National Map Accuracy Standards (NMAS).

Purpose:

Sidewalk Centerlines are used as cartographic elements indicating the centerline of sidewalks. General Services, Parks & Recreation, or Planning may be primary users of miscellaneous arc features.

Supplemental_Information:

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.
OMAGI updates all base map data via photogrammetric process, using aerial imagery that is flown yearly. A different portion of the county is updated each year with the base map maintenance services contract, depending upon development patterns and update funding. The field “UPD_DATE” indicates the date a feature was last re-mapped. For a map of the most recent reviews and updates within the county, please click on https://arcg.is/0Tm9PW0

Status:

Progress: Complete

Maintenance_and_Update_Frequency: Annually

Spatial_Domain:

Bounding_Coordinates:

West_Bounding_Coordinate: -77.963879

East_Bounding_Coordinate: -77.314088

North_Bounding_Coordinate: 39.322606

South_Bounding_Coordinate: 38.836941

Keywords:

Theme:

Theme_Keyword_Thesaurus: none;employee generated

Theme_Keyword: Sidewalk

Theme_Keyword: Centerline

Theme:

Theme_Keyword_Thesaurus: ISO 19115 Topic Categories

Theme_Keyword: structure

Place:

Place_Keyword_Thesaurus: none;employee generated

Place_Keyword: County

Place_Keyword: Loudoun

Place_Keyword: Virginia

Access_Constraints: None

Use_Constraints:

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:

Contact_Information:

Contact_Organization_Primary:

Contact_Organization: Loudoun County, VA, OMAGI

Contact_Position: Base Map Coordinator

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

Country: US

Contact_Voice_Telephone: (703)771-5778

Contact_Facsimile_Telephone: (703)771-5075

Contact_Electronic_Mail_Address: mapping@loudoun.gov

Hours_of_Service: 8:00-4:30 EST, M-F

Native_Data_Set_Environment:

Microsoft Windows Server 2008 Version 6.0 (Build 6002) Service Pack 2; ESRI ArcGIS 10.0.5.4400

Data_Quality_Information:

Attribute_Accuracy:

Attribute_Accuracy_Report:

Miscellaneous Arcs 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:

Attribute_Accuracy_Value: >90% attribute accuracy exists

Attribute_Accuracy_Explanation:

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:

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 2024 imagery.

Positional_Accuracy:

Horizontal_Positional_Accuracy:

Horizontal_Positional_Accuracy_Report:

Accuracy Assessments have been computed according to The National Standard for Spatial Data Accuracy (NSSDA). NSSDA implements a statistical and testing methodology for estimating the positional accuracy of points on maps and in digital geospatial data with respect to georeferenced ground positions of higher accuracy. Accuracy is reported in ground distances at the 95% confidence level. Accuracy reported at the 95% confidence level means that 95% of the positions in the dataset will have an error with respect to true ground position that is equal to or smaller than the reported accuracy value. Data has been tested and meets NSSDA and ASPRS accuracy requirements for 1:2400 scale maps.

Vertical_Positional_Accuracy:

Vertical_Positional_Accuracy_Report: Not Available

Lineage:

Source_Information:

Source_Citation:

Citation_Information:

Publication_Date: 20210427

Title:

RFQ 108783, Agreement for Service for Base Map Maintenance Services, 2020

Source_Scale_Denominator: 2400

Type_of_Source_Media: none

Source_Citation_Abbreviation:

RFQ 108783, Agreement for Service for Base Map Maintenance Services, 2020

Source_Contribution:

Captured and updated photogrammetric stereo models covering selected areas in the Southeast region of Loudoun County.

Process_Step:

Process_Contact:

Contact_Information:

Contact_Organization_Primary:

Contact_Organization: Loudoun County, VA, OMAGI

Process_Description:

1. Legacy PGDB converted to DWG file. 2. DWG file imported to micro station V8 and overlaid with the area to be updated. 3. New features were collected as per the data dictionary and the features that do not exist on 2020 imagery were deleted. 4. Modifications were done if there was a change in the shape and size of the features. 5. All the new and updated features were modified and coded as Update_Date= '2020. 6. Updated data was checked for edge matching. 7. DTM was modified in the update area. 8. Contours were generated, coded and edge matched with the legacy contour data. 9. Spot Elevation Points were placed. 10. All clean up tools were run. 11. Data was exported to PGDB. 12. QA/ QC Program was run and reported errors were corrected. 13. Updated data was checked against 2020 Orthos for completeness. 14. All the delivery blocks were merged into a single PGDB. 15. Updated Data was merged with the Legacy data. 16. Countywide complete dataset (11 layers) was loaded to enterprise SDE

Process_Date: 20210427

Source_Information:

Source_Citation:

Citation_Information:

Publication_Date: 20211206

Title:

RFQ 108783, Agreement for Service for Base Map Maintenance Services, 2020

Source_Scale_Denominator: 2400

Type_of_Source_Media: none

Source_Citation_Abbreviation:

RFQ 108783, Agreement for Service for Base Map Maintenance Services, 2020

Source_Contribution:

Captured and updated photogrammetric stereo models covering selected areas in the South/Central region of Loudoun County.

Process_Step:

Process_Description:

1. Legacy PGDB converted to DWG file. 2. DWG file imported to micro station V8 and overlaid with the area to be updated. 3. New features were collected as per the data dictionary and the features that do not exist on 2020 imagery were deleted. 4. Modifications were done if there was a change in the shape and size of the features. 5. All the new and updated features were modified and coded as Update_Date= '2020. 6. Updated data was checked for edge matching. 7. DTM was modified in the update area. 8. Contours were generated, coded and edge matched with the legacy contour data. 9. Spot Elevation Points were placed. 10. All clean up tools were run. 11. Data was exported to PGDB. 12. QA/ QC Program was run and reported errors were corrected. 13. Updated data was checked against 2020 Orthos for completeness. 14. All the delivery blocks were merged into a single PGDB. 15. Updated Data was merged with the Legacy data. 16. Countywide complete dataset (11 layers) was loaded to enterprise SDE

Process_Date: 20211206

Process_Step:

Process_Contact:

Contact_Information:

Contact_Person_Primary:

Contact_Organization: Loudoun County, VA, OMAGI

Process_Description:

1. Legacy PGDB converted to DWG file. 2. DWG file imported to micro station V8 and overlaid with the area to be updated. 3. New features were collected as per the data dictionary and the features that do not exist on 2022 imagery were deleted. 4. Modifications were done if there was a change in the shape and size of the features. 5. All the new and updated features were modified and coded as Update_Date= '2022. 6. Updated data was checked for edge matching. 7. DTM was modified in the update area. 8. Contours were generated, coded and edge matched with the legacy contour data. 9. Spot Elevation Points were placed. 10. All clean up tools were run. 11. Data was exported to PGDB. 12. QA/ QC Program was run and reported errors were corrected. 13. Updated data was checked against 2022 Orthos for completeness. 14. All the delivery blocks were merged into a single PGDB. 15. Updated Data was merged with the Legacy data. 16. Countywide complete dataset (11 layers) was loaded to enterprise SDE

Process_Date: 20230724

Source_Information:

Source_Scale_Denominator: 2400

Type_of_Source_Media: None

Source_Citation_Abbreviation:

RFQ 108783, Agreement for Service for Base Map Maintenance Services, 2022

Source_Contribution:

Captured and updated photogrammetric stereo models covering selected areas in the Central region of Loudoun County.

Source_Citation:

Citation_Information:

Publication_Date: 20230724

Title:

RFQ 108783, Agreement for Service for Base Map Maintenance Services, 2022

Source_Information:

Source_Citation:

Citation_Information:

Title:

RFQ 108783, Agreement for Service for Base Map Maintenance Services, 2023

Publication_Date: 20240824

Source_Scale_Denominator: 2400

Type_of_Source_Media: None

Source_Citation_Abbreviation:

RFQ 108783, Agreement for Service for Base Map Maintenance Services, 2023

Source_Contribution:

Captured and updated photogrammetric stereo models covering selected areas in the Northern region of Loudoun County.

Process_Step:

Process_Description:

1. Legacy PGDB converted to DWG file. 2. DWG file imported to micro station V8 and overlaid with the area to be updated. 3. New features were collected as per the data dictionary and the features that do not exist on 2023 imagery were deleted. 4. Modifications were done if there was a change in the shape and size of the features. 5. All the new and updated features were modified and coded as Update_Date= '2023. 6. Updated data was checked for edge matching. 7. DTM was modified in the update area. 8. Contours were generated, coded and edge matched with the legacy contour data. 9. Spot Elevation Points were placed. 10. All clean up tools were run. 11. Data was exported to PGDB. 12. QA/ QC Program was run and reported errors were corrected. 13. Updated data was checked against 2023 Orthos for completeness. 14. All the delivery blocks were merged into a single PGDB. 15. Updated Data was merged with the Legacy data. 16. Countywide complete dataset (11 layers) was loaded to enter

Process_Date: 20240824

Spatial_Data_Organization_Information:

Indirect_Spatial_Reference: Loudoun County

Direct_Spatial_Reference_Method: Vector

Point_and_Vector_Object_Information:

SDTS_Terms_Description:

SDTS_Point_and_Vector_Object_Type: String

Point_and_Vector_Object_Count: 396455

Spatial_Reference_Information:

Horizontal_Coordinate_System_Definition:

Planar:

Map_Projection:

Map_Projection_Name: Lambert Conformal Conic

Lambert_Conformal_Conic:

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:

Planar_Coordinate_Encoding_Method: coordinate pair

Coordinate_Representation:

Abscissa_Resolution: 0.00020833333333333297

Ordinate_Resolution: 0.00020833333333333297

Geodetic_Model:

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:

Detailed_Description:

Entity_Type:

Entity_Type_Label: GISDBB.GISBROW.SIDEWALK_TRAIL

Attribute:

Attribute_Label: OBJECTID

Attribute_Definition: Internal feature number.

Attribute_Definition_Source: ESRI

Attribute_Domain_Values:

Unrepresentable_Domain:

Sequential unique whole numbers that are automatically generated.

Attribute:

Attribute_Label: MI_SOURCE

Attribute_Definition: Source that created or modified feature class

Attribute_Definition_Source: Loudyoun Count

Attribute_Domain_Values:

Enumerated_Domain:

Enumerated_Domain_Value: See Entity and Attribute Detail Citation for Data Dictionary

Attribute:

Attribute_Label: MI_UPD_DATE

Attribute_Definition:

The date a feature was last re-mapped, although it may have been reviewed for changes more recently.

Attribute_Definition_Source: Loudoun County

Attribute_Domain_Values:

Unrepresentable_Domain: User generated text

Attribute:

Attribute_Label: MI_UPD_USER

Attribute_Definition:

Not for public distribution. Internal User ID of editor creating or modifying a feature. Intended to track and audit features internally by County.

Attribute_Definition_Source: Loudoun County

Attribute:

Attribute_Label: MI_TYPE

Attribute_Definition: Classification of Miscellaneous Arc Type

Attribute_Definition_Source: Loudoun County

Attribute_Domain_Values:

Enumerated_Domain:

Enumerated_Domain_Value: See Entity and Attribute Detail Citation for Data Dictionary

Attribute:

Attribute_Label: SHAPE

Attribute_Definition: Feature geometry.

Attribute_Definition_Source: ESRI

Attribute_Domain_Values:

Unrepresentable_Domain: Coordinates defining the features.

Attribute:

Attribute_Label: DB2GSE.SdeLength(SHAPE)

Attribute_Definition: Length of feature in internal SDE units

Attribute_Definition_Source: Loudoun County

Overview_Description:

Entity_and_Attribute_Overview:

SI_TYPE: Designation of SIDEWALK_TRAIL line type code description 1 SIDEWALK 2 CONNECTOR 3 CROSSWALK 4 TRAILS 5 FOOTBRIDGE 6 Washington & Old Dominion Railroad Regional Park 7 GOLF CART PATHS (Is this even feasible?)

Entity_and_Attribute_Detail_Citation:

Feature Depiction Descriptions developed according to Loudoun County Data Dictionary.
Sidewalks [Type = 1] Concrete pedestrian walkways directly adjacent or parallel to roads or network through neighborhoods. Sidewalks are different from asphalt-paved fitness paths (see "Trails") that are typically separated from the roads by landscaping or grassy patches and are non-linear in appearance. Impervious road polygons adjacent to sidewalks take precedence over sidewalks. Not included are private walkways leading from residence to driveway or to sidewalk adjacent to road, however, walkways of this same nature (from building to sidewalk or parking lots) in cemeteries and commercial or industrial complexes are to be captured as sidewalks.
Connector [Type = 2] A connector is a segment connecting a sidewalk on one side of a street to a sidewalk on the other side or when a sidewalk crosses over a driveway or entrance to a parking lot. It provides the connectivity to the network where the physical sidewalk ends.
Crosswalk [Type = 3] A marked part of a road where pedestrians have right of way to cross.
Trails [Type = 4] Visible, permanent dirt, gravel or paved passageway greater than 200 ft long primarily used for pedestrian or bicycle traffic. Digitize center line of trail. Different than concrete sidewalks adjacent to roads (see "Sidewalks"). Includes gravel or asphalt-paved fitness paths that are typically separated from the roads by landscaping or grassy patches and are non-linear in appearance. Also includes visible dirt trails through woods that may convey foot, bike, equestrian or 4X4 vehicle traffic. Do not include "farm trails" created by farm equipment or private paths from field to field.
Footbridge [Type = 5] Smaller bridge, typically conveying a sidewalk or trail over a creek or depression. Does not convey cars. Digitize centerline of structure, if trail is present, connect footbridge to sidewalk or trail node to node.
Washington & Old Dominion Railroad Regional Park [Type = 6] Digitize center of regional trail park, see notes under Transportation (RDCASING) polygon Type = 8 for more information.
Golf Cart Paths [Type = 7] Paved cart paths on golf courses that are permanent in nature, and generally adjacent or connecting Golf Course Features (Traps, Tees & Greens), captured in Miscellaneous Cultural Polygons Type = 9.
SI_WIDTH:
2 less than 2 feet 4 2-4 feet 6 4-6 feet 8 6-8 feet 10 8 feet or greater 99 Undetermined
SI_SURFACE:
1 CONCRETE 2 ASPHALT 3 BRICK 4 DIRT OR GRAVEL 5 OTHER

Overview_Description:

Entity_and_Attribute_Overview: MI_SOURCE: Source that created or modified feature class

Entity_and_Attribute_Detail_Citation:

Code Description ---- ------------------ 1 Contract

Distribution_Information:

Distributor:

Contact_Information:

Contact_Organization_Primary:

Contact_Organization: Loudoun County, VA, OMAGI

Contact_Position: Public Information Counter

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

Country: US

Contact_Voice_Telephone: (703)771-5778

Contact_Facsimile_Telephone: (703)771-5075

Contact_Electronic_Mail_Address: mapping@loudoun.gov

Hours_of_Service: 8:00-4:30 EST, M-F

Distribution_Liability:

Chapter 54.1-402 of the Code of Virginia. "Any determination of topography or contours, or any depiction of physical improvements, property lines or boundaries is for general information only and shall not be used for the design, modification, or construction of improvements to real property or for flood plain determination."

Standard_Order_Process:

Digital_Form:

Digital_Transfer_Information:

Format_Name: DXF

Format_Specification: AutoCAD Digital Exchange File

Digital_Transfer_Option:

Offline_Option:

Offline_Media: dvd

Offline_Option:

Offline_Media: dvd

Offline_Option:

Offline_Media: dvd

Fees:

Loudoun County distributes spatial data in ArcGIS database or shapefile or DXF format. Selected aerial imagery is also available.

Ordering_Instructions:

Visit our website at: <http://www.loudoun.gov/omagi> and click on "Maps and 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:

Metadata_Date: 20240824

Metadata_Contact:

Contact_Information:

Contact_Organization_Primary:

Contact_Organization: Loudoun County, VA, OMAGI

Contact_Position: Base Map Coordinator

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: 8:00-4:30 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:

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.