Sidewalk and Trail Centerline Features of Loudoun County, VA (2015)

Metadata also available as

Metadata:

Identification_Information:
Citation:
Citation_Information:
Originator:
Loudoun County, VA, Office of Mapping and Geographic Information (OMAGI)
Publication_Date: 20141222
Title:
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:
Abstract:
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:
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:
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:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date: 20080428
Ending_Date: 20120430
Currentness_Reference: Layer contains features found on aerial imagery up to 2012
Status:
Progress: Complete
Maintenance_and_Update_Frequency: As needed
Spatial_Domain:
Bounding_Coordinates:
West_Bounding_Coordinate: -77.891085
East_Bounding_Coordinate: -77.325717
North_Bounding_Coordinate: 39.322249
South_Bounding_Coordinate: 38.848914
Keywords:
Theme:
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:
Theme_Keyword_Thesaurus: ISO 19115 Topic Categories
Theme_Keyword: society
Theme:
Theme_Keyword_Thesaurus: ISO 19115 Topic Categories
Theme_Keyword: society
Place:
Place_Keyword_Thesaurus: User generated keywords
Place_Keyword: Virginia
Place_Keyword: County
Place_Keyword: Loudoun
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 Cartographer
Contact_Address:
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:
Attribute_Accuracy:
Attribute_Accuracy_Report:
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:
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 2008 imagery.
Positional_Accuracy:
Horizontal_Positional_Accuracy:
Horizontal_Positional_Accuracy_Report:
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:
Horizontal_Positional_Accuracy_Value: Circular RMSE (E, N): 0.7; Tested 1.3 US Survey feet
Horizontal_Positional_Accuracy_Explanation:
Measured at a 95% confidence level, any points measured will be within 1.3 US Survey feet in the horizontal domain.
Vertical_Positional_Accuracy:
Vertical_Positional_Accuracy_Report: Not Available
Lineage:
Source_Information:
Type_of_Source_Media: None
Source_Contribution:
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:
Source_Citation:
Citation_Information:
Publication_Date: 20140203
Title: GPS data collection
Type_of_Source_Media: None
Source_Citation_Abbreviation: GPS data collection
Source_Contribution:
GPS collection of two Loudoun County park trail systems and 2012 digital aerial imagery
Source_Information:
Source_Citation:
Citation_Information:
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:
Loudoun County Miscellaneous Arc Data from 2008 Basemap Update contracted for by Loudoun County, VA OMAGI and 2008 digitial aerial imagery
Process_Step:
Process_Description:
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:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: Loudoun County, VA, OMAGI
Contact_Position: Base Map Cartographer
Process_Step:
Process_Description:
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:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: Loudoun County, VA OMAGI
Process_Step:
Process_Description:
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:
Process_Description:
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:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: Loudoun County, VA OMAGI
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: 55387
Spatial_Reference_Information:
Horizontal_Coordinate_System_Definition:
Planar:
Map_Projection:
Map_Projection_Name: NAD 1983 HARN StatePlane Virginia North FIPS 4501 Feet
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: 0.00032808333333333333
Ordinate_Resolution: 0.00032808333333333333
Planar_Distance_Units: foot_us
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.SIDEWALKS_TRAILS_LINE
Entity_Type_Definition: line feature class
Entity_Type_Definition_Source: ESRI
Attribute:
Attribute_Label: OBJECTID_1
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: ROAD_FROM
Attribute_Definition: Road the feature comes from
Attribute_Definition_Source: Loudoun County
Attribute_Domain_Values:
Unrepresentable_Domain: User generated street name (NA = unsure of road)
Attribute:
Attribute_Label: ROAD_NAME
Attribute_Definition: Name of street feature runs along
Attribute_Definition_Source: Loudoun County
Attribute_Domain_Values:
Unrepresentable_Domain: User generated text
Attribute:
Attribute_Label: SOURCE
Attribute_Definition: Source of feature collection
Attribute_Definition_Source: Loudoun County
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: 1
Enumerated_Domain_Value_Definition: Miscellaneous Arcs Data Set
Enumerated_Domain_Value_Definition_Source: Loudoun County
Enumerated_Domain:
Enumerated_Domain_Value: 4
Enumerated_Domain_Value_Definition: Any other secondary source
Enumerated_Domain_Value_Definition_Source: Loudoun County
Enumerated_Domain:
Enumerated_Domain_Value: 3
Enumerated_Domain_Value_Definition: GPS Collected Feature
Enumerated_Domain_Value_Definition_Source: Loudoun County
Enumerated_Domain:
Enumerated_Domain_Value: 2
Enumerated_Domain_Value_Definition: Aerial Image & on-screen digitization
Enumerated_Domain_Value_Definition_Source: Loudoun County
Attribute:
Attribute_Label: CATEGORY
Attribute_Definition: Type of feature
Attribute_Definition_Source: Loudoun County
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: SHARED USE PATH
Enumerated_Domain_Value_Definition:
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:
Enumerated_Domain_Value: GOLF PATH
Enumerated_Domain_Value_Definition:
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:
Enumerated_Domain_Value: CROSSWALK
Enumerated_Domain_Value_Definition:
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:
Enumerated_Domain_Value: TRAIL
Enumerated_Domain_Value_Definition:
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:
Enumerated_Domain_Value: SIDEWALK
Enumerated_Domain_Value_Definition:
Concrete or asphalt pedestrian walkways directly adjacent or parallel to roads or network through neighborhoods.
Enumerated_Domain_Value_Definition_Source: Loudoun County
Enumerated_Domain:
Enumerated_Domain_Value: WOD
Enumerated_Domain_Value_Definition:
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:
Attribute_Label: SIDE_OF_RO
Attribute:
Attribute_Label: ROAD_TO
Attribute_Definition: Road the feature goes to
Attribute_Definition_Source: Loudoun County
Attribute_Domain_Values:
Unrepresentable_Domain: User generated street name (NA = unsure of road)
Attribute:
Attribute_Label: MATERIAL
Attribute_Definition: Feature material type
Attribute_Definition_Source: Loudoun County
Attribute_Domain_Values:
Unrepresentable_Domain: User generated text
Attribute:
Attribute_Label: MIN_LANDSC
Attribute:
Attribute_Label: MAX_LANDSC
Attribute:
Attribute_Label: WIDTH
Attribute_Definition: Feature width in feet
Attribute_Definition_Source: Loudoun County
Attribute_Domain_Values:
Unrepresentable_Domain: User generated text
Attribute:
Attribute_Label: SUB_CATEGO
Attribute:
Attribute_Label: UPD_DATE
Attribute_Definition: Date that feature was updated
Attribute_Definition_Source: Loudoun County
Attribute_Domain_Values:
Unrepresentable_Domain: User generated text
Attribute:
Attribute_Label: LANDSCAPE_
Attribute:
Attribute_Label: PAINT
Attribute_Definition: Paint type (crosswalks)
Attribute_Definition_Source: Loudoun County
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: STRIPED
Enumerated_Domain_Value_Definition: Crosswalk painted with series of vertical bars
Enumerated_Domain_Value_Definition_Source: Loudoun County
Enumerated_Domain:
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:
Enumerated_Domain_Value: FILL
Enumerated_Domain_Value_Definition: Completely painted-in crosswalk (solid white stripe)
Enumerated_Domain_Value_Definition_Source: Loudoun County
Enumerated_Domain:
Enumerated_Domain_Value: NA
Enumerated_Domain_Value_Definition: Not applicable (for all other CATEGORY values)
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: Shape_STLe
Attribute:
Attribute_Label: SHAPE
Attribute_Definition: Feature geometry.
Attribute_Definition_Source: ESRI
Attribute_Domain_Values:
Unrepresentable_Domain: Coordinates defining the features.
Attribute:
Attribute_Label: Shape.STLength()
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: 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:
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:
Digital_Form:
Digital_Transfer_Information:
Format_Name: DXF
Format_Specification: AutoCad Digital Exchange File
Digital_Transfer_Option:
Offline_Option:
Offline_Media: CD-ROM
Offline_Option:
Offline_Media: CD-ROM
Offline_Option:
Offline_Media: CD-ROM
Fees:
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:
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:
Metadata_Date: 20150727
Metadata_Contact:
Contact_Information:
Contact_Organization_Primary:
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:
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