DATABASE NAME

     MEXICO/HWY:  Mexican Highway Network

DATABASE DESCRIPTION

     Mexican highway network, 1:1,000,000 base-map scale.

ORIGINATING AGENCY

     Volpe National Transportation Systems Center

AGENCY RESPONSIBLE FOR MAINTAINING DATA

     Bureau of Transportation Statistics

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

     1:1,000,000 Digital Chart of the World supplemented by
     editing performed by the Volpe National Transportation
     Systems Center

ACCURACY

     700 m (2,200 ft) root-mean square positional accuracy

TYPE OF GIS DATABASE

     Line database with nodes and links

FILES/SIZE/NUMBER OF RECORDS

     Two files

     1)   mex_hwy.pnt    node file contains node attributes and
                         locations
     2)   mex_hwy.lin    link file contains link attributes and
                         shapes for links

     Approximate size of files:    3,090,000 bytes
     Approximate number of nodes:  8,900
     Approximate number of links:  11,900

FILE STRUCTURE

     The files are ASCII-comma delimited.  Character fields are
     enclosed in quotation marks.

     The Node File

   FIELD  ITEM                TYPE      REMARK

     1    ID                  Num       Unique Identification
                                        number
     2    Longitude           Float     Longitude of node
                                        (decimal degrees with
                                        explicit decimal)
     3    Latitude            Float     Latitude of node (decimal
                                        degrees with explicit
                                        decimal)
     4    Node Type           Char      Future use
     5    Node Description    Char      Future use
     6    Node Description 2  Char      Future use
     7    Long1               Num       Future use
     8    Long2               Num       Future use
     9    Char1_Key           Char      Future use
     10   Char2               Char      Future use
     11   Real1               Float     Future use
     12   Real2               Float     Future use

The Link File

   FIELD  ITEM                TYPE      REMARK

     1    "From" node number  Num       Node ID in mex_hwy.pnt
     2    "To" node number    Num       Node ID in mex_hwy.pnt
     3    ID                  Num       Unique Identification
                                        number
     4    Length              Float     Calculated length of link
                                        (miles)
     5    Direction           Num       Defines link's direction
     6    Type                Char      Type of roadway:
                                        Data from the Digital
                                        Chart of the World
                                        1    Dual-lane highways
                                        2    Primary or secondary
                                             roads or highways
                                        3    Tracks, trails, or
                                             footpaths
                                        8    Connectors
     7    Status              Char      Status of roadway:
                                        Data from the Digital
                                        Chart of the World
                                        1    Functional
                                        2    Under construction
                                        3    Existence doubtful
                                             or reported
                                        4    Compiled road
                                             connector
                                        5    Compiled from
                                             adjacent, more
                                             recent sheet
                                        6    Compiled, under
                                             construction
                                        7    Null or unknown
     8    Long1               Num       Future use
     9    Long2               Num       Future use
     10   Char1_Key           Char      Future use
     11   Char2               Char      Future use
     12   Real1               Float     Future use
     13   Real2               Float     Future use
     14   Real3               Float     Future use
     15   N                   Num       Number of following
                                        longitude-latitude pairs
                                        in decimal degrees
     16   Longitude of "From" Float     Explicit decimal} First
     17   Latitude of "From"  Float     Explicit decimal} pair 
     
          Long.-Lat. pairs    Float     Shape points of the link
          repeat N-2 times    Float     in pairs of long.-lat.

          Longitude of "To"   Float     Explicit decimal}  Final
          Latitude of "To"    Float     Explicit decimal}  pair

DISCUSSION

No additional discussion.