DATABASE NAME

     WTRPOLY:  National Highway System Hydrographic Database

DATABASE DESCRIPTION

     1:100,000 Major water bodies within the United States and
     selected territories.  Hydrographical features represented
     in the database include major rivers, lakes, islands, bays,
     sounds, and a 3-mi offshore limit for coastal states. 
     Navigable channels in rivers and lakes are identified, as
     well as the Gulf and Atlantic Intracoastal Waterways.

ORIGINATING AGENCY

     Federal Highway Administration, Office of Environment and
     Planning

AGENCY RESPONSIBLE FOR MAINTAINING DATA

     Federal Highway Administration, Office of Environment and
     Planning

CONTACT

     National Transportation Atlas Databases
     Bureau of Transportation Statistics
     U.S. Department of Transportation
     Washington, DC  20590
     (202) 366-DATA
     Internet:  info@bts.gov

SOURCE

     1:100,000 Census TIGER/Line records (1991) supplemented by
     editing performed by the University of Tennessee for the
     Federal Highway Administration

ACCURACY

     80 m (260 ft) root-mean square positional accuracy

TYPE OF GIS DATABASE

     Area database with polygons and lines

FILES/SIZE/NUMBER OF RECORDS

     Two ASCII files for each state, Washington DC and Puerto
     Rico:  104 files total

          1)  polygon files contain polygon attributes
          2)  link files contain link attributes and shapes

     File naming convention is as follows:
          polygon file:       sxxhydro.ply
          link file:          sxxhydro.lin
     where xx is the State FIPS code  (see DISCUSSION for list of
     FIPS codes.

     Approximate size of all files:     104,195,000 bytes
     Approximate number of polygons:    
     Approximate number of links:       

FILE STRUCTURE

     The files are ASCII-fixed format.  Character fields are not
     enclosed in quotation marks.

     The Polygon File

     The Polygon Record File contains a single 99 byte record for
     each polygon in the state delimited by a CR/LF.  Each
     Polygon Record contains the following structure:

          COLUMN    TYPE      WIDTH

          RECTYPE   char           1
          VERSION   short int      2
          SOURCE    char           1
          RECID     long int       8
          FEATURE   char           1
          AREA      float          10
          NAME      char           30
          NAVCHAN   char           20
          STFIPS    short int      2
          CENTER_X  float          12
          CENTER_Y  float          12

     Each column is described below.

     RECTYPE
          Data Type:          Character
          Width:              1
          Starting Position:  1
          Domain:             'P'
          Description:        Identifies Polygon Records

     VERSION
          Data Type:          short int
          Width:              2
          Starting Position:  2
          Domain:             positive integers
          Description:        This field describes the release
                              version of the database.  The
                              VERSION code consists of a leading
                              Version Number and a trailing
                              Revision Number; thus, 10 denotes
                              Version 1 Revision 0.  Similarly, a
                              VERSION value of 21 would denote
                              Version 2 Revision 1.

     SOURCE
          Data Type:          Character
          Width:              1
          Starting Position:  4
          Domain:             'U'
          Description:        The SOURCE flag is used to describe
                              the original source of the
                              attribute data in the Polygon
                              Record.  The following flags will
                              be present:
                                   'U'  University of Tennessee
                                        source

     RECID
          Data Type:          long int
          Width:              8
          Starting Position:  5
          Domain:             positive integers
          Description:        The RECID is a unique numeric
                              identifier associated with each
                              Polygon Record.  RECIDs are
                              permanent are not reused.

     FEATURE
          Data Type:          Character
          Width:              1
          Starting Position:  13
          Domain:             'B','C','I','L','O','R','S','W'
          Description:        The FEATURE field describes the
                              feature type of the polygon.
                              The following FEATURE codes are
                              present:
                                   'B'  Bay
                                   'C'  Canal
                                   'I'  Island
                                   'L'  Lake
                                   'O'  Ocean/Offshore
                                   'R'  River
                                   'S'  Sound
                                   'W'  Intracoastal Waterway

     AREA
          Data Type:          float
          Width:              10
          Starting Position:  14
          Domain:             positive real numbers
          Description:        The AREA field is an approximation
                              of the area of the polygon in
                              square decimal degrees.  The area
                              is calculated to 6 decimal places
                              and in many cases is close to or
                              zero.

     NAME
          Data Type:          Character string
          Width:              30
          Starting Position:  24
          Domain:             printable ASCII characters
          Description:        The NAME filed consists of a
                              descriptive name for the polygon
                              feature.  The description is right
                              justified in the field.  Only
                              capital letters are used.  The NAME
                              field may contain embedded blanks.

     NAVCHAN
          Data Type:          Character string
          Width:              20
          Starting Position:  54
          Domain:             printable ASCII characters
          Description:        The NAVCHAN field contains the name
                              of the navigable channel, if any,
                              that runs through the
                              hydrographical feature.  The
                              NAVCHAN field may contain embedded
                              blanks.

     STFIPS
          Data Type:          short int
          Width:              2
          Starting Position:  74
          Domain:             positive integers
          Description:        The FIPS code for the state that
                              the polygon is contained within.

     CENTER_X
          Data Type:          float
          Width:              12
          Starting Position:  76
          Domain:             real numbers
          Description:        The longitude location in decimal
                              degrees (6 decimal places) for the
                              calculated centroid of the polygon.

     CENTER_Y
          Data Type:          float
          Width:              12
          Starting Position:  88
          Domain:             real numbers
          Description:        The latitude location in decimal
                              degrees (6 decimal places) for the
                              calculated centroid of the polygon.

     The Link File

     The Line Record File contains a single 36 byte header record
     for each shoreline in the state database, followed by a list
     of shape points stored in multiple 96 byte records.  The
     maximum number of shape points for any line is set to 500. 
     All records are delimited with a CR/LF.  Line Records are
     either shorelines or closure lines which are used to
     artificially delineate polygon boundaries when no physical
     boundary exists.  For example State borders are modeled as
     closure lines.  Each Line Record contains the following
     structure.

               COLUMN         TYPE      WIDTH

               RECTYPE        char           1
               VERSION        short int      2
               SOURCE         char           1
               RECID          long int       8
               FEATURE        char           1
               STFIPSL        short int      2
               STFIPSR        short int      2
               POLYL          long int       8
               POLYR          long int       8
               NPOINTS        short int      3

     The line record is followed by NPOINTS coordinates tuples
     stored in FORTRAN(8F12.6) format.  Each tuple is stored as
     X,Y (longitude, latitude) in decimal degrees.  Each field in
     the Line File is described more fully below.

     RECTYPE
          Data Type:          Character
          Width:              1
          Starting Position:  1
          Domain:             'L'
          Description:        Identifies Line Records

     VERSION
          Data Type:          short int
          Width:              2
          Starting Position:  2
          Domain:             positive integers
          Description:        This field describes the release
                              version of the database.  The
                              VERSION code consists of a leading
                              Version Number and a trailing
                              Revision Number; thus, 10 denotes
                              Version 1 Revision 0.  Similarly, a
                              VERSION value of 21 would denote
                              Version 2 Revision 1.

     SOURCE
          Data Type:          Character
          Width:              1
          Starting Position:  4
          Domain:             'N', 'T', 'U'
          Description:        The SOURCE flag is used to describe
                              the original source of the
                              topographic data in the Line
                              Record.  The following flags will
                              be present:
                                   'N'  National Oceanic and
                                        Atmospheric
                                        Administration (NOAA)
                                        (1:250,000)
                                   'T'  Census TIGER/Line Records
                                        (1:100,000)
                                   'U'  University of Tennessee
                                        source

     RECID
          Data Type:          long int
          Width:              8
          Starting Position:  5
          Domain:             positive integers
          Description:        The RECID is a unique numeric
                              identifier associated with each
                              Polygon Record.  RECIDs are
                              permanent are not reused.

     FEATURE
          Data Type:          Character
          Width:              1
          Starting Position:  13
          Domain:             'C', 'S'
          Description:        The FEATURE field describes the
                              feature type of the line.  The
                              following FEATURE codes are
                              present:
                                   'C'  Closure line
                                   'S'  Shoreline (perennial)

     STFIPSL
          Data Type:          short int
          Width:              2
          Starting Position:  14
          Domain:             positive integers
          Description:        The FIPS code for the state, to the
                              left, within which the polygon is
                              contained.

     STFIPSR
          Data Type:          short int
          Width:              2
          Starting Position:  16
          Domain:             positive integers
          Description:        The FIPS code for the state, to the
                              right, within which the polygon is
                              contained.

     POLYL
          Data Type:          long int
          Width:              8
          Starting Position:  18
          Domain:             positive integers
          Description:        RECID for the polygon to the left
                              side of the line.

     POLYR
          Data Type:          long int
          Width:              8
          Starting Position:  26
          Domain:             positive integers
          Description:        RECID for the polygon to the right
                              side of the line.

     NPOINTS
          Data Type:          short int
          Width:              3
          Starting Position:  34
          Domain:             positive integers
          Description:        The number of shape points to
                              follow in the Line Record.

DISCUSSION

     November 1993 (Revised September 1994)

     Introduction

     The National Database of Principal Hydrographic Features
     (NDPHF) is a geographic database of major hydrographical
     features in the United States and selected territories. 
     Hydrographical features represent in the database include
     major rivers, lakes, islands, bays, sounds, and a 3 mile
     offshore limit for coastal states.  Navigable channels in
     rivers and lakes are identified, as well as the Gulf and
     Atlantic Intracoastal Waterways.  The NDPHF was developed by
     members of the Geographic Information Systems Laboratory at
     the University of Tennessee, Transportation Center in
     Knoxville, TN for the Federal Highway Administration, Office
     of Planning, Hpp-11.  The database has been developed
     primarily as a mapping database for use within Geographic
     Information Systems and other computer-aided mapping
     software.  It consists of large waterbeds, represented as
     polygon records, and perennial shorelines, represents as
     line records.

     Overview

     The NDPHF contains polygon and line records for the 48
     contiguous states, Washington DC, Alaska, Hawaii, and Puerto
     Rico.  The database is organized by state (or territory) and
     is distributed in two files: a Polygon Record File and a
     Line Record File.  Each file contains fixed length ASCII
     records and is organized such that each state builds as a
     complete set of polygons.  Closure is achieved by adding
     lines (closure lines) to artificially bound polygons where
     not physical boundary exists such as at a state boundary. 
     The database is constructed using a DIME-like file
     structure.  The DIME structure encodes polygon topology onto
     line segments by defining left and right side polygon
     attributes and attributing each line in the database with
     unique direction.  The DIME structure enables polygons
     sharing common boundaries to be modeled simply, without
     redundant lines being present in the database.  A centroid
     is associated with each polygon in the database.  A single
     infinitely large unbounded polygon, termed the external or
     universal polygon, is defined to ensure complete closure of
     all polygons in the database.  Every polygon in the database
     lies within the universe polygon.  The database contains
     1,392 Lake polygons, 12,649 Island polygons, 1,044 River
     polygons, 188 Bay polygons, 109 Offshore polygons, 83
     Intercoastal Waterway polygons, and 19 Sounds polygons.

     Each feature in the database has a unique permanent record
     identifier, and each record contains a descriptive section
     which references the version and source of the original
     data.  The external polygon is always referenced with a
     polygon of 0 (zero).  Note that the universe polygon has no
     polygon record or centroid associated with it.  Appendix A
     details the number of polygon and line records for each
     state database.

     Data Sources

     The NDPHF has been developed by combining CENSUS TIGER/Line
     records (CENSUS 1991) with coastline vectors from the
     National Oceanic and Atmospheric Administration National
     Ocean Service (NOS) D Scale Digital Shoreline files (Release
     1.0, Feb. 1992).  The NOS D Scale shoreline files are
     1:250,000 nominal scale vector databases covering the
     Atlantic, Gulf of Mexico, and the Pacific coast (files
     NOSD01, NOSD02, and NOSD03 respectively).  The D-scale
     shorelines files were created by NOS by generalizing a more
     detailed (1:40,000) C-scale shoreline database.

     Attribute information for the polygon records was obtained
     primarily from various map sources.  Area attributes for he
     polygons were calculated using Arc/Info V6.1.1 GIS Software
     (ESRI 1991).  Navigable waterway attributes were transcribed
     from a map titled "Major Waterways and Ports of the United
     States and Selected Territories (Eng. Map 4d)," published by
     the Permanent International Association of Navigation
     Congress, 20 Massachusetts Avenue NW, Washington DC 20314-
     1000.  This map was created by data from the US Army Corps
     of Engineers (1989).  A complete listing of the Navigable
     Waterways is given in Appendix B.  Other map features and
     attributes such as closure lines and FIPS codes were added
     by members of the development staff.

     APPENDIX A
          State               FIPS      Polygons       Lines
          Alabama             01         169            650
          Alaska              02        2012           2497
          Arizona             04          29            143
          Arkansas            05         197            726
          California          06         361            582
          Colorado            08          29             80
          Connecticut         09         134            174
          Delaware            10          31             73
          Washington DC       11           4             21
          Florida             12        2625           3016
          Georgia             13         184            574
          Hawaii              15          77            197
          Idaho               16          27            173
          Illinois            17          83            309
          Indiana             18          53            157
          Iowa                19
          Kansas              20          33            174
          Kentucky            21          43            323
          Louisiana           22        1333           1849
          Maine               23        1589           1860
          Maryland            24         261            558
          Massachusetts       25         225            268
          Michigan            26         144            426
          Minnesota           27         128            433
          Mississippi         28         142            426
          Missouri            29          66            401
          Montana             30          25            294
          Nebraska            31          41            157
          Nevada              32          14             76
          New Hampshire       33          51            127
          New Jersey          34         259            368
          New Mexico          35          13             80
          New York            36         243            430
          North Carolina      37         641           1030
          North Dakota        38          29            165
          Ohio                39          67            175
          Oklahoma            40          96            579
          Oregon              41         460            608
          Pennsylvania        42          47            165
          Rhode Island        44          49             63
          South Carolina      45         320            662
          South Dakota        46          37            265
          Tennessee           47          76            615
          Texas               48        1801           2518
          Utah                49          14            189
          Vermont             50          29             74
          Virginia            51         463            730
          Washington          53         447            628
          West Virginia       54          16             81
          Wisconsin           55          92            345
          Wyoming             56          43            193
          Puerto Rico         72         104            220

     APPENDIX B  Navigable Waterways

     ALABAMA             KENTUCKY            SAN PABLO
     ALLEGHENY           KILL VAN KULL       SAVANNAH
     APALACHICOLA        LAKE WASHINGTON     SENECA
     ARCTIC              SHIP                SHIP CHANNEL
     ARKANSAS            LAKE WASHINTON      SNAKE
     ARTHUR KILL         MERMENTAU           SUISON
     ATCHAFALAYA         MICHIGAN            SUPERIOR
     ATLANTIC ICW        MINNESOTA           TECHE
     ATLANTIC            MISSISSIPPI         TENNESSEE
     BEAUFORT            MISSOURI            TENNESSEE-
     BERING              MOBILE              TOMBIGBEE
     BLACK WARRIOR       MOHAWK              TRINITY
     BRAZOS              MONONGAHELA         VERDIGRIS
     CALCASIEU           NANTICOKE           WHITE
     CALMUNET            NAPA                WICOMICO
     CAPE FEAR           NEUSE               WILLAMETTE
     CARRIBEAN           NEWARK              YAZOO
     CHAMPLAIN           OHIO                YORK
     CHATTAHOOCHEE       OKEECHOBEE WW       YUKON
     CHICAGO             ONTARIO
     CHOPTANK            OSWEGO
     CHOWAN              OUACHITA
     CLINCH              PACIFIC
     COLUMBIA            PAMLICO
     CONNECTICUT         PASCAGOULA
     CUMBERLAND          PASSAIC
     DELAWARE            PATAPSCO
     DETROIT             PEARL
     DISMAL SWAMP        PENOBSCOTT
     EAST                POCOMOKE
     ERIE CANAL          POTOMAC
     ERIE                RAPPAHANNOCK
     FLINT               RARITAN
     GREEN               RED
     GULFICW             ROANOKE
     GULF OF MEXICO      SABINE
     HACKENSACK          SACRAMENTO
     HARLEM              SAGINAW
     HOUSTON             SAINT CLAIR
     HUDSON              SAINT CROIX
     HURON               SAINT JOHNS WW
     ILLINOIS            SAINT JOHNS
     JAMES               SAINT LAWRENCE
     KANAWHA             SAN FRANCISCO
     KASKASKIA           SAN JOAQUIN
     