Metadata: Identification_Information: Citation: Citation_Information: Originator: Roger Tankersley, Jr. Publication_Date: 1998 Title: roads Edition: 1 Geospatial_Data_Presentation_Form: Map Publication_Information: Publication_Place: Norris TN Publisher: Tennessee Valley Authority Description: Abstract: This map is an ARC/INFO coverage of all roads in the mid-Atlantic region. Class 1-4 roads (the ones included here) include major highways to unimproved roads. Purpose: These data were created as part of a regional assessment of landscape conditions in the mid-Atlantic region (SFR 3) (Jones et al., 1997). Time_Period_of_Content:1995 Time_Period_Information: Range_of_Dates/Times: Beginning_Date: Ending_Date: Currentness_Reference: None Status: Progress: Complete Maintenance_and_Update_Frequency: None planned Spatial_Domain: Bounding_Coordinates: West_Bounding_Coordinate: -84 degrees West East_Bounding_Coordinate: -74 degrees West North_Bounding_Coordinate: 43 degrees North South_Bounding_Coordinate: 36 degrees North Keywords: Theme: Theme_Keyword_Thesaurus: None Theme_Keyword:Roads Theme_Keyword: Theme_Keyword: Theme_Keyword: Theme_Keyword: Theme_Keyword: Place: Place_Keyword_Thesaurus: None Place_Keyword: United States Place_Keyword: Standard Federal Region III Access_Constraints: None Use_Constraints: None Point_of_Contact: Contact_Information: Contact_Person_Primary: Bruce Jones Contact_Person: Contact_Organization: EPA Landscape Ecology Division Contact_Address: Address_Type: mailing and physical address Address: U.S. Environmental Protection Agency, Box 93478 City: Las Vegas State_or_Province: Nevada Postal_Code: 89193-3478 Contact_Electronic_Mail_Address: jones.bruce@epamail.epa.gov Data_Set_Credit: USGS RF3 data. Native_Data_Set_Environment: These data are presently stored in ARC/INFO format. Data_Quality_Information: Attribute_Accuracy: Attribute_Accuracy_Report: none Logical_Consistency_Report: none Completeness_Report: Complete Positional_Accuracy: Horizontal_Positional_Accuracy: Horizontal_Positional_Accuracy_Report: None Source_Information: Source_Citation: Citation_Information: Other_Citation_Details: Jones, K.B., Riitters, K.H., Wickham, J.D., Tankersley, R.D., O'Neill, R.V., Chaloud, D.J., Smith, E.R., and Neale, A.C. 1997. An Ecological Assessment of the United States Mid-Atlantic Region: A Landscape Atlas. EPA/600/R97/130, U.S. Environmental Protection Agency, Office of Research and Development, Washington, DC. Source_Information: Source_Citation: Citation_Information: Other_Citation_Details: Process_Step: Process Description: The RF3 file is based upon the USGS 1:100,000 scale hydrography DLGs. The data were acquired by EPA-OW on 240 tapes which contained 54,000 files. The first processing performed was to convert from UTM to latitude/longitude. This conversion was accomplished preserving the nearest 1/10,000 of a degree, which is well within the stated resolution of these data. The data were then collapsed into line records (trace files) without nodes, and the line records were concatenated. There were then 4 million line elements and 93 million latitude/longitude coordinates. Each line, or trace, retained a key record that can be directed back to the original DLG data tape if necessary. Traces were then assigned to USGS Cataloging Units (CU). Traces that crossed CU boundaries were assigned to both CUs. A CU is a geographic area representing all or part of a surface drainage basin, a combination of basins, or a distinct hydrologic feature. There are approximately 2150 CUs in the Nation. The USGS CU boundaries were developed at a scale of 1:2,000,000 (see Figure 1). They represent the "smallest element in the hierarchy of hydrologic units" (U.S. Geological Survey, 1982). CUs are not accurately correlated to topography and do not always correspond directly to true watersheds as they are more administrative in function. Horizon Systems Corporation, the prime contractor to EPA-OW, developed a software tool called PC Reach File (PCRF). PCRF is the program that performs the RF3 file construction. Production development of RF3 proceeds in discrete units corresponding to the CU. Because of the ability to run many of the steps in batch, a given analyst running PCRF may be working on as many as 25 CUs at a time. Building The RF3 Network. In order to update the RF2 file to RF3, the RF2 data, the DLG data and the CU boundaries are all downloaded to a PC running PCRF. There, an analyst identifies a starting point for the automated construction of the network topology. The starting point designated was the furthest reach downstream and the network was built up in the reverse direction of flow. Between reaches there may be gaps, usually along map sheet boundaries. Therefore, a search tolerance of 3/10,0000 of a degree or approximately 100 feet was specified in order to "bridge" these gaps. Edgematching takes place by the addition of segments in these gaps. Once this has been completed, the analyst will "replay" and supervise the network that was created. There may be some network discrepancies that are not able to be resolved by PCRF and that may cause a break in the processing. These are resolved by the analyst. Once the network is built, segment and milepoint numbers must be assigned along the network. The analyst begins this session by viewing both the RF2 and the processed DLG data together, color coded for differentiation. The analyst then will "tag" the RF2 segment endpoints to the corresponding DLG points. PCRF will then work upstream from the downstream end of the segment and allocate milepoints. The RF2 milepoints are retained in RF3, despite the actual length of the new segments. In other words, the milepoint figures will not reflect the true length of the RF3 reaches. For example, if an RF2 segment had ten reaches (differentiated by milepoints), the more detailed RF3 segment will also have ten milepoints, but the trace of these reaches will be entirely different. New milepoints are not being created because this would disrupt databases that index to the earlier Reach Files. The actual length of reaches as derived from the DLG trace is recorded in a field called SEGL. New segments and reaches are not an uncommon outcome of this conversion to the more highly resolved hydrography network. In this step, PCRF will assign new SEG/MI numbers to traces that appear in the 1:100,000 DLG that did not exist in the previous 1:500,000 Trace File. Source_Used_Citation_Abbreviation: Source_Produced_Citation_Abbreviation: Process_Date: Spatial_Data_Organization_Information: Direct_Spatial_Reference_Method: vector Raster_Object_Information: Raster_Object_Type: Row_Count: Column_Count: Spatial_Reference_Information: Horizontal_Coordinate_System_Definition: Planar: Map_Projection: Map_Projection_Name: Lambert_Azimuthal Lambert_Azimuthal: Radius of Sphere of Reference: 6370997 Longitude_of_Central_Meridian: -100 0 0 Latitude_of_Projection_Origin: 45 0 0 False_Easting: 0.0 False_Northing: 0.0 Planar_Coordinate_Information: Planar_Coordinate_Encoding_Method: Row and column Coordinate_Representation: Abscissa_Resolution: Ordinate_Resolution: Planar_Distance_Units: meters Entity_and_Attribute_Information: Detailed_Description: Entity_Type: Entity_Type_Label: Entity_Type_Definition: Entity_Type_Definition_Source: ARC/INFO Attribute: Attribute_Label: ORDER Attribute_Definition: Stream order, ranging from 1st-7th. Attribute_Definition_Source: ARC/INFO Attribute_Domain_Values: Range_Domain: Range_Domain_Maximum: Range_Domain_Minimum: Attribute_Measurement_Frequency: None planned Attribute: Attribute_Label: CODE Attribute_Definition: RF3 Reach Type Code. Attribute_Definition_Source: ARC/INFO Attribute_Domain_Values: Range_Domain: Range_Domain_Maximum: Range_Domain_Minimum: Attribute_Measurement_Frequency: None planned Overview_Description: Entity_and_Attribute_Overview: Entity_and_Attribute_Detail_Citation: Not available Distribution_Information: Distributor: Contact_Information: Contact_Person_Primary: Contact_Person: Bruce Jones Contact_Organization: EPA Landscape Ecology Division Contact_Address: Address_Type: Address: U.S. Environmental Protection Agency, Box 93478 City: Las Vegas State_or_Province: Nevada Postal_Code: 89193-3478 Contact_Electronic_Mail_Address: jones.bruce@epamail.epa.gov Metadata_Reference_Information: Metadata_Date: 19980901 Metadata_Contact: Contact_Information: Contact_Person_Primary: Contact_Person: Roger Tankersley, Jr. Contact_Organization: University of Tennessee, Department of Geography Contact_Address: Address_Type: Address: 428 G&G Building Address: City: Knoxville State_or_Province: TN Postal_Code: 37996 Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata Metadata_Standard_Version: 19940608 Metadata_Security_Information: Metadata_Security_Classification_System: None Metadata_Security_Classification: Unclassified Metadata_Security_Handling_Description: None