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