National Transportation Atlas Database (NTAD)

Overview

Data Dictionary

Examples of Uses of Data

Potential Uses of Data

Overview

The National Transportation Atlas Database (NTAD) is a collection of geo-spatial databases developed by the U.S. Department of Transportation and other federal agencies depicting transportation facilities, networks, and services of national significance (http://www.bts.gov/gis/ntatlas/index.html). It contains a compilation of geographic databases that provide the infrastructure for national planning and policy initiatives for the U.S. Department of Transportation. These data sets include geospatial information for transportation modal networks and intermodal terminals, and related attribute information. (http://www.bts.gov/gis).

These databases are designed to be used with Geographic Information System (GIS) software packages to locate transportation features and provide a framework for transportation network analysis. The databases are most useful at the national level, but have major applications at the regional, state, and local scale throughout the transportation community.

The NTAD is a cooperative effort throughout the US Department of Transportation and other Federal agencies. The Federal Highway Administration (FHWA), the Federal Railroad Administration (FRA), the US Army Corps of Engineers (USACE), the US Bureau of the Census, the National Park Service (NPS), the Federal Aviation Administration (FAA), the Federal Transit Administration (FTA), and the Bureau of Economic Analysis (BEA) supplied data for this project.

The NTAD database is updated annually, incorporating updates of attribute fields as well as all corrections and enhancements made to the geography and/or topology since the previous release.

Between each version release, the BTS will post interim updates on its internet site, incorporating corrections identified by users and enhancement work in progress. Interim updates will include both a transaction database, containing only those records which have been updated since the last major release, and a transaction log file, identifying what specific changes were made to each updated record.

The NTAD was started in 1995, but it was produced by contractors before there was a GIS staff at BTS. There was no quality control, there was no standard data format, and there were many mistakes on the CD. The first "usable" NTAD was NTAD 1996. NTAD 1997 is updated based on NTAD1996. NORTAD is a special release of NTAD for 1998, which includes border crossings (US-Canada and US-Mexico), Canada, Mexico, and the United States. The updates to NTAD 1997 are the US part of NORTAD. NTAD will return in 1999, with a projected release date of April 1999.

Overview of database categories

NTAD 1997 includes geospatial information for national transportation modal networks and intermodal terminals, and related attributes developed by U.S Department of Transportation and other Federal agencies annually. It can be obtained for no charge by downloading from the Bureau of Transportation Statistics web site or requesting CDs from the Bureau of Transportation Statistics. There are three broad categories of information in this database. They are transportation facilities databases, transportation network databases, and background databases of geographic entities. These are outlined briefly below.

Transportation facilities databases

Transportation facilities databases depict the locations of transportation terminals, intermodal transfer facilities, and key transportation structures such as bridges, tunnels, and navigation aids. These are typically represented as point features.

Attributes associated with transportation facilities include information on facility capacity and special features, current traffic through the facility, and common facility classifications.

These transportation facilities are included in the database:

• Public Use Airports:

• Runway:

• Trailer on Flatcar/Container on Flatcar:

• Amtrak Station:

• Water Port Facilities:

• Autoramp:

Transportation network databases contain topologically connected lines depicting the locations and centerline alignments of nationally significant roads, railroads, waterways, airways, and transitways. Nodes associated with these transportation networks may represent transportation terminals or interchange facilities, junctions, or intersections with other geographic features.

Attributes associated with transportation networks include route names or numbers, capacity measures, various network classifications, and traffic volumes. All U.S. transportation networks in the NTA have been constructed to a geographic accuracy consistent with that of a 1:100,000-scale map.

These transportation network databases are included:

• National Highway Planning Network Version 2.1

• National Railway Network -- 1:100,000

• National Railway Network -- 1:2,000,000

• National Waterway Network

• National Transit Network

• Commercial Air Network

Background databases (geographic entities) are typically area databases depicting administrative or statistical boundaries such as states and counties, congressional districts or military bases. These area databases are used in conjunction with transportation networks and other facilities to provide a locational frame of reference or a base for demographic or environmental information. They are represented by polygon features.

Attributes associated with background databases include feature or place name, area measures, and census data aggregated to the area level. Most background database boundaries in the National Transportation Atlas (NTA) have been digitized to a geographic accuracy consistent with that of 1:100,000-scale map.

These background databases are included:

• Place Names:

• United States:

• U.S. Counties [updated November 13, 1997]:

• Urbanized Areas:

• Federally Adjusted Urbanized Areas:

• Congressional Districts:

• Metropolitan Statistical Areas:

• Bureau of Economic Analysis Regions:

• National Transportation Analysis Regions:

• National Parks:

• Military Bases (Not yet available):

The Bureau of Transportation Statistics (BTS) has created a standard set of file formats for geospatial databases included in the National Transportation Atlas (NTA). These formats were developed to make it easier to view and extract NTA data by establishing a common structure for each of the three geospatial feature types depicted in the NTA: points, networks, and areas. These formats are also being provided to GIS software vendors so that they can develop translation software to import the databases directly into their own internal formats. The BTS will distribute all of its geospatial data using these formats as an interim standard until a formal Transportation Network Profile (TNP) is adopted as part of the Spatial Data Transfer Standard (SDTS). The file format descriptions and database metadata are prescribed by the Federal Geographic Data Committee (FGDC).

The BTS geospatial file formats are based on a set of standard record types. Six distinct record types are currently defined: Link, Node, Point, Area, Geography, and Attribute (a seventh record type, Linear Reference, is still under development, but will eventually be added to this set). Each of the three spatial feature types included in the NTA consists of an interrelated combination of these record types defining the geometry, topology, and attributes associated with a specific transportation or background feature. Feature types and their composite record types are described below:

Transportation Networks are composed of four related record types: Link, Node, Geography, and Attribute. Examples of transportation networks are highways, railroads, and waterways.

Transportation Point Facilities such as airports, water ports, and truck terminals require only two related record types: Point and Attribute.

Areas are made up of three related record types: Area, Geography, and Attribute. Features such as Congressional Districts, States, and National Parks are examples of areas.

Each geospatial database distributed by the BTS will consist of a set of files sharing a common file name and file extensions identifying the corresponding record type. File names will be consistent with DOS file naming conventions (e.g., eight characters or less, no spaces, etc.). The file extensions for each record type are given below:

• .lnk: link record type
• .nod: node record type
• .pnt: point record type
• .are: area record type
• .geo: geography record type
• .tXX (t01, t02, etc.): attribute record type (a geospatial database may have more than one attribute or table file)

TABLE 1 – Fields Contained in All Files
 

Field	Description
RECTYPE	The RECTYPE identifies the record type associated with the file, where:  L Link N Node P Point A Area G Geography T Attribute This field will have the same value for each record in the file.
VERSION	The version number is a 2-digit number that will be incremented for all records in the database whenever a new release is distributed.
REVISION	The revision number is a 2-digit number that will be incremented individually for each record whenever a change is made to one of its fields. Revision numbers are also included in the transaction log file so that database users can identify what specific change was made to the record. Revision numbers will not be reset with each new release
MODDATE	The modification date indicates when each record in the database was last changed. For release 0100 this field is blank. As changes are made to a record, the modification date is entered in the format 'mmddyyyy'.

 

In addition, the link, node, point, area, geography, and attribute files contain several identification and location fields. These fields vary by type of file, as outlined in Table 2.
 
 

TABLE 2 – Standard Fields in Link, Node, Point, Area, Geography, and Attribute Files
 

Field	Link File	Node File	Point  File	Area File	Geography File	Attribute File	Description
LINKID	X						A unique sequential number assigned to each record in the link file. It is used internally by most GIS software to index records and to establish topological relationships between spatial objects. It is not permanent and may change between different versions of the file.
NODEID		X					A unique sequential number assigned to each record in the node file. It is used internally by most GIS software to index records and to establish topological relationships between spatial objects. It is not permanent and may change between different versions of the file.
POINTID			X				A unique sequential number assigned to each record in the point feature file. It is used internally by most GIS software to index records. It is not permanent and may change between different versions of the file.
POLYID				X			A unique sequential number assigned to each record in the area file. It is used internally by most GIS software to index records and to establish topological relationships between spatial objects. It is not permanent and may change between different versions of the file.
LINEID					X		A unique sequential number assigned to each record in the geography file. It is used internally by most GIS software to index records and to establish topological relationships between spatial objects. In transportation networks the field name is LINKID, and matches the LINKID field in the Link File. It is not permanent and may change between different versions of the file.
FEATURID	X	X	X	X		X	A unique character string or numeric value associated with the spatial feature. The metadata associated with each network database describes the significance of and method for assigning this identifier. Any changes made in the FEATURID will be recorded in a transaction file maintained by the BTS and distributed with each new version of the database.
ANODE	X						Identifies a record (NODEID) in the node file that corresponds to the starting position of the link.
BNODE	X						Identifies a record (NODEID) in the node file that corresponds to the ending position of the link.
DESCRIPT	X	X	X	X			Can contain any character string describing a feature, such as a river name, route id name, or number. These descriptions need not be unique for each record.
STFIPS		X	X	X			Contains the FIPS code for the State in which the feature is located. If the feature is located on the border of two or more States, this field contains 00. If the node is located outside the borders of the United States, the field contains 99.
STFIPS1	X						Contains the FIPS code for the State in which the link is located. If the link borders two States, STFIPS1 contains the lower numeric value FIPS code.
STFIPS2	X						Contains the higher numeric value FIPS code for a second State in those cases where the link borders two States. If the link is located completely within a State, this field contains 00. In no case should a link border three or more States because a node should exist at the point where the States intersect.
LONGITUDE		X	X				The longitude of the node expressed as a signed integer with six (6) implied decimal places.
LATITUDE		X	X				The latitude of the node expressed as a signed integer with six (6) implied decimal places.
CNTRLONG				X			The longitude of the area feature record centroid expressed as a signed integer with six (6) implied decimal places.
CNTRLAT				X			The latitude of the area feature record centroid expressed as a signed integer with six (6) implied decimal places.
POLYINL					X		The polygon identification number (POLYID) from the area file for the polygon record located on the left side of the line. For transportation networks, this field is blank.
POLYINR					X		The polygon identification number (POLYID) from the area file for the polygon record located on the right side of the line. For transportation networks, this field is blank.
NPOINT					X		The number of coordinate pairs (longitude and latitude) that define the shape of the linear feature and follow the header record. For transportation networks, the geography file includes the coordinates of both the start and end nodes of the link as well as all intermediate shape points. Therefore every linear feature will have at least two coordinate pairs.

 

Link File

The link file contains basic information related to transportation network links. Each record contains the four standard fields (RECTYPE, VERSION, REVISION, MODDATE, defined above) plus seven additional fields.

Node File

The node file contains basic information related to transportation network nodes. Each record contains the four standard fields (RECTYPE, VERSION, REVISION, MODDATE, defined above) plus six additional fields.

Point File

The point file contains basic information related to transportation point features and is similar to the network node file. Each record contains the four standard fields (RECTYPE, VERSION, REVISION, MODDATE, defined above) plus six additional fields.

Area File

The area file contains basic information related to area features. Each record contains the four standard fields (RECTYPE, VERSION, REVISION, MODDATE, defined above) plus six additional fields.

Geography File

The geography file contains the shape information for network links or area boundaries. The file structure includes a header record followed by a variable number of shape point records. The header record contains the four standard fields (RECTYPE, VERSION, REVISION, MODDATE, defined above) plus four additional fields.

Attribute Files

The attribute file(s) contains additional information about network links or nodes, or point or area features. There may be multiple attribute files associated with any geospatial feature database, and each attribute file may have a different number of attributes and different attribute formats. However, each specific attribute file is characterized by a fixed format and fixed record lengths.

Each record in an attribute file contains the four standard fields (RECTYPE, VERSION, REVISION, MODDATE, defined above), one feature identification field, and a variable number of attribute fields.

The FEATURID is a unique character string or numeric value associated with the geospatial feature, and matches the FEATURID field in the corresponding Link, Node, Point, or Area files. This field provides the relational link between the spatial object which is used to represent a feature and the various attributes associated with it.

The FEATURID field is followed by a variable number of attribute fields pertaining to the feature. Data descriptions and formats for each attribute field are defined in the metadata for the geospatial database.

In addition to fixed format, fixed record length ASCII files, the BTS plans to distribute attribute files in dBase format. Many existing GIS software package can read dBase files directly, and this will obviate the need for users of those packages to build import templates for each attribute file.

Above descriptions are general file format for NTAD 1997. The detailed descriptions of file format for facilities (point), networks (line), and area (polygon) follow.

Point Features

TOFC/COFC Facilities

TOFC/COFC facilities originated and published by the Bureau of Transportation Statistics. The TOFC/COFC facilities database is a geographic database of trailer-on-flatcar (TOFC) and container-on-flatcar (COFC) highway-rail and/or rail-water transfer facilities in the United States. Attribute data specify the intermodal connections at each facility; i.e., the reporting marks of the railroad serving the facility, the type of cargo (always containers/trailers), and the direction of transfer. The purpose of this database is to provide location and attribute information for use in national and regional cartographic and network analysis applications.

Attribute Accuracy: Attribute data were extracted from the IANA 1997 Rail Intermodal Terminal Directory, the Official Railway Guide; the TTX Company Intermodal Directory; World Wide Web home pages of Burlington Northern Santa Fe, Conrail, CSX Transportation, Kansas City Southern, and Norfolk Southern; U.S. Army Corps of Engineers Port Series Reports; Containerization International Yearbook; 1996 AAPA Directory; and various transportation news sources both in print and on the Internet. Attribute data reflect conditions at TOFC/COFC facilities during 1995-96 and are subject to frequent change. Some facilities may be dormant or permanently closed.

Logical Consistency: All point records are represented by a single coordinate pair and a unique feature identifier of the form SSCCC-NNNN, where SS is the 2-digit State FIPS code, CCC is the 3-digit county FIPS code, and NNNN is a sequence number within the state/county. Attribute data are matched to specific point records using this identifier.

Horizontal Positional Accuracy: The locations of TOFC/COFC facilities were determined using available facility address information and MapExpert, a commercial nationwide digital map database and software package, and recording the longitude/latitude of the approximate center of the facility. Facility locations are not bound to any current or previous highway, railway, or waterway network models.

Process Description: TOFC/COFC facilities identified from various sources were located using MapExpert, a commercial nationwide digital map database and software package, supplemented with other available spatial reference aids, including paper maps, aerial photographs, and published railroad atlases. The computer pointing device cursor was placed over the approximate location of the terminal and the displayed longitude/latitude was recorded. Attribute data were appended to each point.

There are three files describing TOFC/COFC facilities: TOFCCOFC.PNT, TOFCCOFC.T01 and TOFCCOFC.DBF. TOFCCOFC.PNT describes the point features. The file format is the same as that listed in Tables 1 and 2. Attribute tables are provided in two formats, fixed-format text (TOFCCOFC.T01) and dBase (TOFCCOFC.DBF). The file structure is listed in Table 3 (the four common fields are described in Table 1).

TABLE 3 TOFCCOFC.T01/TOFCCOFC.DBF
 

Field	Field Type	Field Width	Description
MODE1	C	1	First connecting mode H Highway R Rail W Water
MODE2	C	1	Second connecting mode H Highway R Rail W Water
RRID	C	4	Railroad name abbreviation
CARGO	I	3	Type of cargo transferred from Oak Ridge National Laboratory
DIRECTN	I	1	Direction of transfer: 1-way or 2-way

Public-Use Airports

The Public-Use Airports database is a geographic point database of aircraft landing facilities in the United States and U.S. Territories. Attribute data is provided on the physical and operational characteristics of the landing facility, current usage including enplanements and aircraft operations, congestion levels and usage categories. The database provides locational and attribute information for use in national and regional cartographic and spatial analysis applications.

Attribute Accuracy: Airport attributes were obtained from four different Federal Aviation Administration (FAA) sources: the National Flight Data Center Airport Master Record (NFDC 5010) database; the National Plan of Integrated Airport Systems (NPIAS) database; the Air Carrier Activity Information System (ACAIS) database, and the Terminal Area Forecast (TAF) file. Each database has its own collection and quality control procedures, and all are maintained by separate offices in FAA. Where two or more of the databases included a similar attribute field, an assessment was made as to which value was more current and/or more accurate based on its data collection procedures. Attributes derived from the same source are grouped together.

For each ASCII attribute file a corresponding dBase format attribute file is supplied. Due to the requirement for the file name extension 'dbf', the attribute file number is included in the file name prefix (AIRPORT.T02 contains the same attributes as AIRPORT2.DBF).

In all attribute files, a number of the attributes contain 'blank' in addition to the values enumerated in the domain.

In attribute file two (AIRPORT.T02), the National Emergency Status field (NAT_EMER_STAT) contains values not enumerated in the domain. It is a composite field that may contain multiple values separated by '/'. The non-enumerated values include: 3, X, N, 8/N, and 'blank'.

Although some records were modified, the data provider supplied no modification date(s), nor any change code in the REVISION field.

Logical Consistency: All point records are represented by a single coordinate pair and a unique feature identifier -- the landing facility's location identifier (LOCID) assigned by the FAA. Attribute data is matched to specific point records using this LOCID.

Horizontal Positional Accuracy: Horizontal positional accuracy is based on coordinate data provided in the NFDC 5010 database. These coordinate data identify the approximate location of the Airport Reference Point (ARP) as reported by the landing facility on the NFDC 5010 form. According to NFDC guidelines, the location of the ARP should be reported to a horizontal accuracy of one arc second of latitude and longitude. However, the accuracy of these reported coordinates are not verified by FAA. The records were loaded into a GIS and checked visually for any unusual or obviously erroneous locations. Grossly incorrect locations were repositioned using Census TIGER/Line files or USGS digital line graphs (DLG) as reference layers. No more than five records required repositioning in this manner. Further accuracy checks using the NTAD states database and the Digital Chart of the World as reference layers revealed no further positioning errors with the 1:100,000 NTAD database, but about five airports on islands appeared to be slightly in the ocean according to the 1:1,000,000 scale Digital Chart of the World. Comparison of the NTAD layout of Puerto Rico with that of the Digital Chart of the World revealed enough of an error in the Digital Chart of the World's location of Puerto Rico to think that Saint Thomas' airport, which appeared to be in the ocean according to the Digital Chart of the World, might really be on land, given the known high accuracy of most of the airport coordinates obtained from the NFDC 5010 database. Therefore, the few airports that appeared to be slightly off of their islands according to the Digital Chart of the World were left at their original coordinates.

When compared with the NTAD STATES database, approximately 120 airports appear to lie off-shore or not within the state boundary based upon the STFIPS Code attribute.

Five facilities are identified as requiring additional review to properly locate the facilities.

The facilities in question are:

POINTID FEATURID STFIPS DESCRIPT

2498 ADW 24 Andrews AFB

3253 DC13 11 Walter Reed Forest Glen

5077 NK29 36 Southampton Village

5170 NY93 36 Charles Poletti

6492 WA65 53 Washington National Guard – Sinclai

For example, the Charles Poletti facility is coded as existing in New York state. The coordinates place it in Pennsylvania. The airport points should carry the same longitude and latitude values as the airway segment endpoints (carrying the LOCID as FEATURID to match the points and nodes). In most cases they do. The longitude and latitude value for Denver International Airport (DEN) does not match the value for the associated node. Airport longitude, latitude point = -104.667002, 39.858408 Airway node longitude, latitude = -104.879755, 39.774292

Process Description: Selected attribute fields from the four FAA databases were merged based on the common LOCID. Documentation for the 1995 Public Use Airports Database, prepared by Robert Waksman, Volpe Center, Cambridge, MA, January 1996.

The airport point feature is stored in file AIRPORT.PNT. Its data dictionary and file formats are the same as those listed in Table 1 and Table 2 . Attribute information is stored in four separate files, one for each of the FAA source databases. A data dictionary and file formats for all attributes included in this database are provided in Table 4.

AIRPORT.T01/AIRPORT1.DBF originated from the Air Carrier Activity Information System (ACAIS) data file. Reformatted into an ASCII format for incorporation into a geographic information system.

TABLE 4 AIRPORT.T01/AIRPORT1.DBF
 

Field	Field Type	Field Width	Description
ACAIS_AP	C	1	Air Carrier Activity Information System Airport Yes
LCAC_ENP	I	8	Large Certified Air Carrie Enplanements
COMM_ENP	I	8	Commuter Enplanements
AT_ENP	I	8	Air Taxi Enplanements
FFAC_ENP	I	8	Foreign Flag Air Carrier Enplanements
IT_ENP	I	8	In-transit Enplanements
TOT_ENP	I	8	Total Enplanements
ENP_SAN	C	1	Sanitized Enplanement Data 0 – no data was sanitized 1 – the foreign enplanement data was sanitized 2 – the in-transit enplanement data was sanitized
HUB_TYPE	C	1	Hub Airport Type (>1% large, 0.25-1% medium, 0.05-0.25% small, <0.05% nonhub, general aviation) L – large M – medium S – small N – non-hub G – general aviation
SVC_LVL	C	2	Facility Service Level PR - Primary commercial service airport CM - Commercial service other than primary airport CR - Commercial service airport that also serves as a reliever airport  GA - General aviation airport RL - General aviation airport that serves as a reliever airport or heliport GP - General aviation airport that meets the criteria for a primary airport (PR), but has been declared ineligible to be a primary airport RP - General aviation airport that meets the criteria for a primary airport(PR), serves as a reliever airport, but has been declared ineligible to be a primary airport GC - General aviation airport that meets the criteria for a commercial service other than a primary airport (CM), but has been declared ineligible to be a commercial airport

Table 5 shows AIRPORT.T02/AIRPORT2.DBF originating from the National Flight Data Center (NFDC) file. It was reformatted into an ASCII format for incorporation into a geographic information system.

TABLE 5 AIRPORT.T02/AIRPORT2.DBF
 

Field	Field Type	Filed Width	Description
SITE_NUM	C	11	Site Number
FAC_TYPE	C	1	Facility Type  A - Airport H - Heliport C - Seaplane Base S - STOLport
FAC_NAME	C	42	Facility Name
CITY	C	26	City location of the facility
COUNTY	C	21	County location of the facility
STATE	C	2	State Postal Code abbreviation for the facility
CTY_FIPS	C	3	County FIPS Code for the facility
FAA_REG	C	3	FAA Region AAL - Alaska ACE - Central AEA - Eastern AGL - Great Lakes ANE - New England ANM - Northwest Mountain ASO - Southern ASW - Southwest AWP - Western-Pacific
FAC_USE	C	2	Facility Use, public or private
OWN_TYPE	C	2	Type of owner PU - Publicly owned PR - Privately owned MA - Air Force owned MN - Navy owned MR - Army owned
OWN_NAME	C	30	Name of owner
ELEVATION	I	6	Elevation in feet
CBD_DIST	I	3	Distance from the central business district
CERT_TYPE	C	3	Codes AS, BS, CS, DS, ES are for landing facilities having a full certificate under FAR Part 139 and receiving scheduled air carrier service from carriers certified by the Civil Aeronautics Board. The A, B, C, D, E identifies the aircraft rescue and fire fighting index for the landing facility, and the 'S' is for scheduled air carrier service.  Codes AU, BU, CU, DU, EU are for landing facilities having a full certificate under FAR Part 139 but not currently receiving scheduled service.  Code 'LS' is for landing facilities having limited certification under FAR Part 139 and receiving scheduled air carrier service.  Code 'LU' is for airports having limited certification under FAR Part 139 and not currently receiving scheduled air carrier service. 'N' or a blank indicates the facility is not certified.
CERT_DATE	C	5	Date of facility certification
CUST_INTL	C	1	Customs International Airport Y – yes N - no
C_LDG_RTS	C	1	Customs Landing Rights Airport Y – yes N - no
JOINT_USE	C	1	Joint Use Y – yes N - no
MIL_RTS	C	1	Military Landing Rights Y – yes N - no
NAT_EMER	C	18	National Emergency Status 1 - Airport certified under FAR Part 139 2 - Civil airport where military use is subject to lease.  3P - Airport is partially released from national emergency use provision 3E - Airport is entirely released from national emergency use provision.  4 - Airport includes surplus real property which has been conveyed for, or converted to, revenue production.  5 - Exclusive military use airport.  6 - The airport is in the process of disposal or reversion.  7P - A letter of intent has been issued to release a part of the airport property.  7E - A letter of intent has been issued to release the entire airport property.  8 - An exclusive right has been granted (whether or not in violation of an agreement).  8P - An exclusive right has been granted (whether or not in violation of an agreement); however, this exclusive right is of the type 8N - An exclusive right exists through a P.L. 80-289 deed providing exemption for fuel and oil sales; however, an exclusive right for fuel oil sales has not been granted.
MIL_EMER	C	6	Military Emergency Interest A - Air Force R - Army N - Navy X - None (applicable only where there is an entry in the National Emergency Status [NAT_EMER] Field)
B_MIL_AC	I	2	Number of operational military aircraft based at the facility
RUN_NUM	I	2	Number of runways at the facility
PAD_NUM	I	2	Number of helicopter pads at the facility

Table 6 shows AIRPORT.T03/AIRPORT3.DBF originating from the National Plan of Integrated Airport Systems (NPIAS) data file. It was reformatted into an ASCII format for incorporation into a geographic information system

TABLE 6 AIRPORT.T03/AIRPORT3.DBF
 

Field	Field Type	Field Width	Description
WPIAS_AP	C	1	National Plan of Integrated Airport System airport Y-yes
VFRHRCAP	I	4	Visual Flight Rule hourly capacity
IFRHRCAP	I	4	Instrument Flight Rule hourly capacity
CONG_LVL	C	1	Congestion Level S - Severe  M - Moderate  U - Uncongested O - Should be in database, but entry missing
LNG_FLT	C	1	Long Flight Category S - Short (less than 500 statute miles) M - Medium (500 to 1,500 statute miles) L - Long (more than 1,500 statute miles) O - Should be in database, but entry missing N - Entry not applicable to the landing facility
AC_TYPE	C	2	Aircraft Type HV - DC-10, B-747, L-1011, A-300, A-310, B-767 CT - Aircraft with 30 seats or less TP - All other transport type aircraft, having more than 30 seats but smaller than 'HV' aircraft, e.g., DC-9, B-727 O - Should be in database, but entry missing N - Entry not applicable to the landing facility
FED_LDG	C	4	Federal Landing Interest  JNT - Military airport with a joint-use agreement MAIL - Civil airport with mail service MLTY - Civil airport with a military tenant For landing facilities in this database that have a blank in this field, it cannot be determined whether an entry is not applicable or entry should be in the database, but the entry is missing.

Table 7 shows AIRPORT.T04/AIRPORT4.DBF originating from the Terminal Area Forecast (TAF) file. It was reformatted into an ASCII format for incorporation into a geographic information system.

TABLE 7 AIRPORT.T04/AIRPORT4.DBF
 

Field	Field Type	Field Width	Description
TAF_AP	C	1	Terminal Area Forecast (TAF) Airport Y - yes
AT_TYPE	C	1	Air Tower Type 0 = No tower  1 = Tracon, Rapcon, Cerap 2 = Radar tower 3 = Limited radar tower 4 = Non-radar tower 5 = VFR tower 6 = Non-FAA facility 7 = Contract tower
AC_IO	I	8	Air Carrier Itinerant Operations
AI_IO	I	8	Air Taxi Itinerant Operations
GA_IO	I	8	General Aviation Itinerant Operations
MIL_IO	I	8	Military Itinerant Operations
TOT_IO	I	8	Total Itinerant Operations
GA_LOC_O	I	8	Total local general aviation operations
MIL_LOC_O	I	8	Total local military operations
TOT_LOC_O	I	8	Total local operations
TOT_LOC_O	I	8	Total operations

 

Places

The National Populated Places database is a geographic database of populated places in the United States containing information on the location and 1990 Census population. The database includes places in all 50 states as well as US territories. The data provide users with information about the locations, names, and 1990 populations of places primarily for national planning applications.

There are two files describing the point feature of the place databases: PLACE90.PNT and PLACE90.T01/PLACE90.DBF. The data dictionary and file format for PLACE90.PNT is the same as that listed in Table 2. The common fields of PLACE90.T01/PLACE90.DBF are also the same as those listed in Table 1. The other fields of PLACE90.T01/PLACE90.DBF are summarized in Table 8.

TABLE 8 PLACE90.T01/PLACE90.DBF
 

Field	Field Type	Field Width	Description
POP	I	9	1990 Population
HU	I	9	1990 Housing Units
FULL_NAME	C	66	Full Place Name
STATE	C	2	State Postal Abbreviation

 

Ports

The US Army Corps of Engineers (USACE) Ports database is an extract from the National Waterway Network database consisting of 184 points coded as US Army Corps of Engineers ports. The Ports database is a geographic database of the US Army Corps of Engineers Ports in and around the United States, for analytical studies of waterway performance, for compiling commodity flow statistics, and for mapping purposes.

Attribute Accuracy: Attribute accuracy is tested by manual comparison of the source with hard copy printouts and/or symbolized display of digital line graphs on an interactive computer graphic system; selected attributes that cannot be visually verified on plots or on screen, are interactively queried and verified on screen.

Horizontal Positional Accuracy: The accuracy of each point element is correlated to the data source used to derive that element. For example, links and nodes derived from 1:100,000 scale Digital Line Graphs are more accurate than links and nodes derived from 1:500,000 scale NOAA Navigational Charts. Elements with an "M" in the source field (indicating an unknown or missing source) are the least accurate.

There are two files describing the point feature of the port database: PORT.PNT and PORT.T01/PORT.DBF. The data dictionary and file format for PORT.PNT is the same as that listed in Table 2. The common fields of PORT.T01/PORT.DBF are also the same as those listed in Table 1. The other fields of PORT.T01/PORT.DBF are summarized in Table 9.

TABLE 9 PORT.T01/PORT.DBF
 

FIELD	FIELD TYPE	FIELD WIDTH	DESCRIPTION
PORT	C	15	Unique port code
STATE	C	2	State Abbreviation XX – non US area
NON_US	C	2	Non U.S. Area Abbreviation AC - Arctic Ocean AT - Atlantic Ocean BS - Bering Sea CB - Caribbean Sea CD - Canada GM - Gulf of Mexico PC - Pacific Ocean PM - Panama XX - Undefined Area
WHO_MOD	C	3	Who modified the link first character: V - Vanderbilt addition R - Oak Ridge addition J - guessed H - screen digitization from DLGs or TIGER Q - digitized from USGS quad maps A - digitized from NOAA charts second character: 0 original 1 94 May 2 94 June 3 94 July blank after July 1994 third character: R attributes modified by ORNL A attributes modified by Vanderbilt
SRC	C	5	Source of the node V1 - Digitized from NOAA Charts V2 - Digitized from 1:100K USGS Quads V3 - Imputed from ORNL port V4 - Imputed from Corps port V5 - Digitized from 1:100K DLGs V6 - Digitized from State or World Boundary V7 - Imputed from Corps Lock location O1 - Oak Ridge estimate C - Corps M - Missing / Unknown

 

Amtrak Stations

The Amtrak Stations database is a geographic database of intercity railroad passenger facilities in the United States. Attribute data includes the railroads providing service at the station and AMTRAK services. The database provides locational and attribute information for use in national and regional cartographic and network analysis applications.

Attribute Accuracy: Attribute data were extracted from the 1994 Amtrak timetables, and reflects conditions as of late 1994 and early 1995.

Logical Consistency: All point records are represented by a single coordinate pair and a unique feature identifier -- the Amtrak Station Code (stored in the FEATURID field). Attribute data is matched to specific point records using this identifier. A number of Amtrak Stations have no value assigned to the FEATURID. Use the POINTID field as the linking field.

Completeness: The database includes all Amtrak Stations listed in the 1994 Amtrak timetables. It does not include regional commuter railroad stations which are not also served by Amtrak; these stations are currently included in the Fixed-Guideway Transit and Ferry Network. The database also does not include information on passenger boardings; this information is considered to be proprietary by Amtrak.

Horizontal Positional Accuracy: Stations were located by matching station names to places identified in the Standard Point Location Code (SPLC) database and/or other reference maps, and then adjusting the coordinates to coincide with the corresponding railway centerline in the FRA 1:2 million National Railroad Network. Absolute positional accuracy is therefore no better than that of the rail network itself.

Process Description: Each Amtrak passenger station identified in the Amtrak timetable was manually located on the 1:2 million National Railroad Network using a variety of spatial reference aids, including paper maps, the USGS Geographic Names Information System, and the Standard Point Location Code database. Attribute data was appended to each point record using information contained in the Amtrak timetable.

Each Amtrak passenger station was compared to the NTAD STATES database to determine whether the point exists inside the boundary of the state of the assigned State FIPS Code. A few Amtrak Stations were repositioned using published Amtrak schedules to identify addresses. Using address matching, the "correct" station locations were determined. The "correct" station location information for these six stations is based on the TIGER/Line file database.

There are three files describing the point feature of the Amtrk station database: AMTK_STA.PNT and AMTK_STA.T01/AMTKSTA1.DBF. The data dictionary and file format for AMTK_STA.PNT is the same as point file listed in Table 2. The common fields of AMTK_STA.T01/AMTKSTA1.DBF and AMTK_STA.T02/AMTKSTA2.DBF are also the same as attribute file listed in Table 1. The other fields of AMTK_STA.T01/AMTKSTA1.DBF and AMTK_STA.T02/AMTKSTA2.DBF are summarized in Table 10 and Table 11.
 
 

TABLE 10 AMTK_STA.T01/AMTKSTA1.DBF
 

Field	Field Type	Field Width	Description
TICKOFF	C	1	Station includes ticket office Y - yes
HPACCESS	C	1	Station Handicap access Y - yes
CUSTOMS	C	1	Station customs office Y - yes
THRUWYPT	C	1	Station is a through way location Y -yes
AMTRKEXP	C	1	Station includes Amtrak Express Y – yes
CREATVAC	C	1	Station includes Great Vacations Y – yes
SELFTIC	C	1	Station has self ticketing Y – yes
CHECKBAG	C	1	Station has bag checking Y - yes
STATE	C	2	State Postal Abbreviation

 

TABLE 11 AMTK_STA.T02/AMTKSTA2.DBF
 

Field	Field Type	Field Width	Description
SEQ_NUM	I	2	Sequence Number  1 through 5 as assigned
RR	C	5	Railroad Name abbreviation

 

Autoramps

The Auto Ramp Facilities database is a geographic database of terminals where motor vehicles are transferred between rail and highway modes and/or between rail and water modes in the continental United States. Attribute data specify the intermodal connections at each facility; i.e., the modes involved in the intermodal transfer, the AAR reporting marks of the railroad serving the facility, the type of cargo (in this case, motor vehicles), and the direction of the transfer. The database provides location and attribute information for use in national and regional cartographic and network analysis applications.

Attribute Accuracy: Attribute data were extracted from the Association of American Railroads' Motor Vehicle Loading and Unloading Terminals directory, U.S. Army Corps of Engineers Port Series Reports, and various transportation news sources both in print and on the Internet. Attribute data reflect conditions at auto ramp facilities during mid-1995 and are subject to frequent change. Some facilities included in the database may now be dormant or permanently closed.

Logical Consistency: All point records are represented by a single coordinate pair and a unique feature identifier of the form SSCCC-NNNN, where SS is the 2-digit State FIPS code, CCC is the 3-digit county FIPS code, and NNNN is a sequence number within the state/county. Attribute data are matched to specific point records using this identifier.

Completeness: The database includes auto ramp facilities and marine automobile terminals with rail connections which were listed or cited in one or more of the following sources: Association of American Railroads' Motor Vehicle Loading and Unloading Terminals directory, U.S. Army Corps of Engineers Port Series Reports, and various transportation news sources both in print and on the Internet. The database reflects the status of auto ramp facilities as of mid-1995. Because of the frequent turnover of this type of facility, some of the terminals included in the database may now be dormant or permanently closed.

Horizontal Positional Accuracy: The locations of auto ramp facilities were determined using available facility address information and MapExpert, a commercial nationwide digital map database and software package, and recording the longitude/latitude of the approximate center of the facility. Facility locations are not bound to any current or previous highway, railway, or waterway network models.

Process Description: Auto ramp facilities identified from various sources were located using MapExpert, a commercial nationwide digital map database and software package, supplemented with other available spatial reference aids, including paper maps, aerial photographs, and published railroad atlases. The computer pointing device cursor was placed over the approximate location of the terminal and the displayed longitude/latitude was recorded. Attribute data were appended to each point.

There are two files describing the point feature of the autoramp database: AUTORAMP.PNT and AUTORAMP.T01/AUTORAMP.DBF (intermodal connection table). The data dictionary and file format for AUTORAMP.PNT is the same as point file listed in Table 2. The common fields of AUTORAMP.T01/AUTORAMP.DBF are also the same as attribute file listed in Table 1. The other fields of AUTORAMP.T01/AUTORAMP.DBF are summarized in Table 12.

TABLE 12 AUTORAMP.T01/AUTORAMP.DBF
 

Field	Field Type	Field Width	Description
MODE1	C	1	First connecting mode H – highway R – rail W - water
MODE2	C	1	Second connecting mode H – highway R – rail W - water
RRID	C	4	Railroad name abbreviation
CARGO	I	3	Type of cargo transferred
DIRECTN	I	1	Direction of transfer: 1-way or 2-way

 

Line Features

Waterways

The National Waterway Network is a comprehensive network database of the nation's navigable waterways. The data set covers the 48 contiguous States plus the District of Columbia, Hawaii, Alaska, Puerto Rico and water links between. The nominal scale of the data set varies with the source material. The majority of the information is at 1:100,000 with larger scales used in harbor/bay/port areas and smaller scales used in open waters. The National Waterway Network is a geographic database of navigable waterways in and around the United States, for analytical studies of waterway performance, for compiling commodity flow statistics, and for mapping purposes.

Supplemental Information: Links in the waterway network represent actual shipping lanes or serve as representative paths in open water where no defined shipping lanes exist. Nodes may represent physical entities such as river confluences, ports/facilities, and intermodal terminals, US Army Corps of Engineers (USACE nodes), or may be inserted for analytical purposes. Approximately 180 USACE ports are geocoded in the node database.

Attribute Accuracy: Attribute accuracy is tested by manual comparison of the source with hard copy printouts and/or symbolized display of digital line graphs on an interactive computer graphic system; selected attributes that cannot be visually verified on plots or on screen, are interactively queried and verified on screen.

Horizontal Positional Accuracy: The "shape source" field in the link database, and the "node source" field in the node database indicate the data sources used to derive link and node placements. The accuracy of each network element is correlated to the data source used to derive that element. For example, links and nodes derived from 1:100,000 scale DLGs are more accurate than links and nodes derived from 1:500,000 scale NOAA Navigational Charts. Elements with an "M" in the source filed (indicating an unknown or missing source) are the least accurate. Links with unknown/missing sources are usually schematic representations of USACE links.

Off-Shore: NOAA Charts vary in scale. Larger scale charts were used in harbor/port areas, while smaller scale charts were used in open water. For channels, sea lanes, and Intracoastal Waterways, shape points were placed as needed to ensure that link segment fall within waterway boundaries.

Inland: Links digitized from 1:100,000 DLG files, or large scale NOAA charts are the most accurate representations. Shape points were placed as needed to ensure that link segments fall between waterway shorelines. Links derived from Corps milepoints have shape points approximately one mile apart. The Corps milepoints were mainly derived from 1:24,000 and 1:100,000 scale maps. Therefore, the shape points derived from Corps milepoints are often as accurate as shape points derived from 1:100,000 DLG files. However, line segments connecting the shape points may not accurately represent the curvature of the waterway.

Process Description: Merging of inland and offshore waterway networks. A specialized program was written to merge the two networks. In general, Vanderbilt node locations were accepted as authoritative when both data sets had the same elements. This meant moving an Oak Ridge link incident to that node. If the link was classified geographically ocean or Great Lakes, and a Vanderbilt link or chain existed with the same ID and endpoints, the Oak Ridge link was discarded, after transfer of Oak Ridge attributes. If the Oak Ridge link was within 2 km of the new end nodes' location: and 1) if a duplicate Vanderbilt link existed with a higher source code, it replace the Oak Ridge link, or 2) the Oak Ridge link was moved by a logistic adjustment to the new location. (This causes modest disruption to the preponderance of the shape, yet assured that the angle of approach to the displaced end node location was preserved.) If the link was functionally classed "deep draft" and a duplicate Vanderbilt link had an authoritative source code, the Oak Ridge link was replaced. Otherwise an additional shape point was added at the end to snap to the new node location without disrupting the original link shape. If the link had a Vanderbilt duplicate with the same ID, the Oak Ridge link was so flagged to be manually resolved. The composite network was then cleaned manually, resolving all cases of still remaining duplicate links and deciding case-by-case how to smooth or otherwise accommodate a highly displaced Oak Ridge shape into the Vanderbilt digitized node location, using TIGER shorelines as a background.

Heads-up digitizing of WWAY10 to add shape points to inland waterways where straight links still existed. Incorporation of comments from users (Vanderbilt, ORNL, and USACE Waterborne Commerce Statistics Center) of WWAY10 and error correction.

There are five files describing the waterway database: WATERWAY.LNK, WATERWAY.NOD, WATERWAY.GEO, WATERWAY.TL1,WATERWAY.TN1/WATETN1.DBF. The data dictionary and file format for WATERWAY.LNK, WATERWAY.NOD, WATERWAY.GEO are same as link file, node file and geography file listed in Table 2. The common fields for WATERWAY.TL1,WATERWAY.TN1/WATETN1.DBF are same as attribute file as listed in Table 1. The other fields of WATERWAY.TL1,WATERWAY.TN1/WATETN1.DBF are listed in Table 13 and Table 14.

TABLE 13 WATERWAY.TL1/WATERTL1.DBF
 

Field	Field Type	Field Width	Description
DESCRIP2	C	35	Secondary link description
AMILE	N	10	Milepost at the ANODE
BMILE	N	10	Milepost at the BNODE
LLEN	N	7	Link length in miles
LENSRC	C	1	Source of link length V - Vanderbilt; length was calculated using GIS software M - Milepoints; length was calculated by subtracting 'B' milepoint from 'A' milepoint
SHAPESRC	C	6	Source of line shape CM - Corps Milepoints DD - Digitized from 1:100K DLGs (CD-ROM) DN - Digitized from NOAA Charts DQ - Digitized from 1:100K USGS Quads J - Rough shape (guessed) JR - Original shape modified by ORNL JV - Original shape modified by Vanderbilt M - Missing / Unknown NA - Digitized from 1:2M National Atlas Points RR - ORNL link modified by ORNL RV - ORNL link modified by Vanderbilt VR - Vanderbilt link modified by ORNL
LINKTYPE	C	10	Type of link CORPS - Corps of Engineers original link CWIS - Corps of Engineers civil works improvement addition ORNL - Oak Ridge National Laboratory VANDERBILT - Vanderbilt University LOCK - Corps of Engineers lock
CTRLD	I	10	Control depth, in feet control depth = -1 where unknown
WTWY	I	10	Four-digit waterway code
GEO	I	3	C Geographic Class G = Great Lakes O = Ocean / Offshore I = Inland
FUNC	C	2	Functional Class N no traffic, non-navigable S shallow draft (i.e., no deep draft ocean vessels) D deep draft B both U special vessels only (fishing, pleasure craft, etc; normally no freight traffic)
WTYPE	I	6	Waterway type 1 - Harbor (including harbor channels), Bay 2 - Intracoastal Waterway 3 - Sealane 4 - Sealane with separation zone 5 - Open water 6 - River, creek, thoroughfare, lake 7 - Estuary 8 - Channel (not including harbor channels) 9 - Canal 10 - Great Lakes direct link (major ports) 11 - Great Lakes indirect link 12 - Corps of Engineers Lock
CHART	C	15	Chart number
NUMPR	I	9	Number of coordinate pairs
WHOMOD	C	3	Same as before
HEADING	C	1	Compass Direction
STATE	C	2	Same as before
NON_US	C	2	Same as before

 

TABLE 14 WATERWAY.TN1/WATERTN1
 

Field	Field Type	Field Width	Description
PORT	C	15	Same as before
STATE	C	2	Same as before
NON_US	C	2	Same as before
WHO_MOD	C	3	Same as before
SRC	C	5	Same as before

 

Fixed-Guideway Transit and Ferry Systems

The Fixed-Guideway Transit and Ferry network is a comprehensive network database of the nation's fixed-guideway transit and ferry systems. The data set covers systems in cities within the 48 contiguous States plus the District of Columbia and Puerto Rico, and includes heavy rail, light rail, monorail, ferry boat, cable car, dedicated HOV roadway, inclined plane, and automated guideway. The data provide users with information about the location and type of fixed-guideway transit and ferry network and terminal facilities primarily for regional cartographic, spatial and network analysis purposes.

Attribute Accuracy: Attribute information was obtained from individual transit agencies through telephone conversations and follow-up written material provided by the agency. The level of detail and completeness of this information varied, depending on the source. Attribute data were transcribed directly into the database with no independent verification.

This version of the dataset includes no node attributes.

When modifying the dataset, the provider did not consistently code the MODDATE or the REVISION field.

In the transit.lnk file, the STFIPS1 and STFIPS2 fields are intended to define the adjacent states where a line segment acts as a boundary. On four lines, these fields contain the 'from' or 'to' STFIPS Code. On three lines, the STFIPS2 field contains ' 1'. None of these lines are adjacent to Alabama (STFIPS = 01).

Logical Consistency: Networks were checked for connectivity during database construction and again prior to dissemination on the National Transportation Atlas CD-ROM. Duplicate links were removed.

In the process to verify feature location based on the NTAD STATES dataset, the verifier split a number of line segments. Based on the attributes included in the dataset, there is no apparent reason for these modifications.

The data provider inconsistently coded the LINKID and FEATURID fields when modifying the dataset. The end user may not be able to link the features in the 1997 version back to the 1996 features.

Completeness: This database includes all fixed-guideway transit and ferry lines identified by the Federal Transit Administration as recipients of Federal transit funding. Excluded are some small fixed guideway systems operating without Federal funding and certain ferry lines which may receive Federal Highway funding in lieu of transit funding.

Attribute data is incomplete at this time, and what data is included reflects information received from individual transit agencies during 1994.

Horizontal Positional Accuracy: Right-of-ways for fixed guideways were digitized from a variety of source material received from individual transit agencies. These materials ranged from engineering drawings to stylized system maps. Based on the material provided, alignments were traced against TIGER/Line street networks as basemaps. At best, the resulting alignments are no more accurate than the TIGER/Line street network for specific urban areas.

A number of ferry lines were added that appear to cross through islands when compared with the NTAD STATES dataset.

Process Description: Using source materials received from individual transit agencies, fixed guideway centerline networks were digitized against TIGER street networks. Stations were located using addresses and other cues provided from the source material. Each fixed guideway system was put in its own database.

The TRANSIT dataset was compared with the NTAD STATES dataset to verify the correct feature location based on the State FIPS Code.

There are four files describing the transit database: TRANSIT.LNK, TRANSIT.NOD, TRANSIT.GEO, TRANSIT.TL1/TRANSIT1.DBF. The data dictionary and file format for TRANSIT.LNK, TRANSIT.NOD, TRANSIT.GEO are same as link file, node file and geography file listed in Table 2. The common fields for TRANSIT.TL1/TRANSIT1.DBF are same as attribute file as listed in Table 1. The other fields of TRANSIT.TL1/TRANSIT1.DBF are listed in Table 15.

TABLE 15 TRANSIT.TL1/TRANSIT1.DBF
 

Field	Field Type	Field Width	Description
DESCRIPT	C	35	Name or identification for the line feature MONORAIL INCLINED PLANE CABLE CAR FERRY BOAT AUTOMATED GUIDEWAY HOV LANES LIGHT RAIL HEAVY RAIL
RTS_SRVD	C	35	Routes Served
GRD_ELEV	I	1	Grade/elevation 1 - At grade 2 - Elevated 3 - Below grade 4 - On structure
TR_TYPE	C	3	Track Type AG - Automated Guideway  CC - Cable Car FB - Ferry Boat HOV - High-occupancy vehicle lanes HR - Heavy Rail IP - Inclined Plane LR - Light Rail MR - Monorail
UZA	C	25	Urbanized Area Name
STATUS	I	1	Status 1 - Planned 2 - Out of service 3 - Active 4 - Construction - Not defined

 

Runways

A comprehensive geographic database of runways in the United States containing information on the physical characteristics of the runways. The database includes runways in all 50 states as well as US territories. The 9513 runways in the database are supposed to include all of the runways associated with the 6734 airports in the companion geographic 1995 AIRPORTS DATABASE. This data provides users with information about the runway locations and attributes for national and regional analysis applications.

Currentness: ground conditions and annual summaries

Attribute Accuracy: Data were obtained almost exclusively from the Federal Aviation Administration's (FAA) National Flight Data Center (NFDC) 5010 landing facilities database for September 1995.

A number of the attributes contain values not enumerated in the domain: Many fields also contain 'blank' The runway surface field (RWY_SFC) also contains: ASHP-F, ALUMN-MAT, GRVD, TRTD, BRICK, CORAL, GRVL, METAL, PFC, PSP, SAND, SOD, and WOOD. The metadata states that the characteristics are separated by a dash (-). In some instances, a slash (/) is used instead.

Both visual glide slope fields (BE_VGS and RE_VGS) contain values not listed in the enumerated domain. These include: 3.0, 3.00, r, and 4.00. Both Approach light system fields (BE_ALS and RE_ALS) contain values not listed in the enumerated domain. These include: RAIL, SALS, and SALSF.

Both Object Affecting Navigable Airspace fields (BE_OANA and RE_OANA) contain combination values not listed in the enumerated domain. Additionally, the field contains values not enumerated, plus inconsistent coding, including: A(ND), A(U), A(V, AV), B (V), B(NP), C(NP), D, H(V), and NPI.

Logical Consistency: All point records are represented by a single coordinate pair and a unique feature identifier -- the landing facility's location identifier (LOCID) assigned by the FAA.Attribute data is matched to specific point records using the LOCID.

Although some records were modified, the data provider supplied no modification date(s), nor any change code in the REVISION field. Many coincident lines exist in this dataset.

Completeness: Landing facilities in this database consist of those identified in the NFDC 5010 database to be either publicly owned, or privately owned but open to the public, or owned by the U.S. military. The following landing facilities have been excluded: private landing facilities not open to the public, glider ports and ultra light landing facilities, as well as landing facilities that do not have a current LOCID assigned to them. In attribute file runway.tl1, a blank in an attribute field for a particular runway could signify either that an entry is not applicable or that the data is missing. Only in some cases will the user of the data be able to determine which case applies.

Horizontal Positional Accuracy: Horizontal positional accuracy is based on coordinate data provided in the NFDC 5010 database. These coordinate data identify the approximate location of the Airport Reference Point (ARP) as reported by the landing facility on the NFDC 5010 form. According to NFDC guidelines, the location of the ARP should be reported to a horizontal accuracy of one arc second of latitude and longitude. However, the accuracy of these reported coordinates are not verified by FAA. The records were loaded into a GIS and checked visually for any unusual or obviously erroneous locations. Grossly incorrect locations were repositioned using Census TIGER/Line files or USGS digital line graphs (DLG) as reference layers. No more than five records required repositioning in this manner. Further accuracy checks using the NTAD STATES database and the Digital Chart of the World as reference layers revealed no further positioning errors with the 1:100,000 NTAD STATES database but runways on about five airports on islands appeared to be slightly in the ocean according to the 1:1,000,000 scale Digital Chart of the World. Comparison of the NTAD STATES layout of Puerto Rico with that of the Digital Chart of the World revealed enough of an error in the Digital Chart of the World's location of Puerto Rico to think that Saint Thomas' airport and runways, which appeared to be in the ocean according to the Digital Chart of the World, might really be on land, given the known high accuracy of most of the airport and many of the runway coordinates obtained from the NFDC 5010 database. Therefore, the few runways and airports that appeared to be slightly off of their islands according to the Digital Chart of the World were left at their original coordinates.

When compared with the NTAD STATES database, approximately 170 runways appear to lie off-shore or not within the state boundary based upon the STFIPS Code attribute.

There are four files describing the airport runway database: RUNWAY.LNK, RUNWAY.NOD, RUNWAY.GEO, RUNWAY.T01/RUNWAY.DBF. The data dictionary and file format for RUNWAY.LNK, RUNWAY.NOD, RUNWAY.GEO are same as link file, node file and geography file listed in Table 2. The common fields for RUNWAY.T01/RUNWAY.DBF are same as attribute file as listed in Table 1. The other fields of RUNWAY.T01/RUNWAY.DBF are listed in Table 16.

TABLE 16 RUNWAY.T01/RUNWAY.DBF
 

Field		Field Type	Filed Width		Description
SITE_NO		C	11		Unique air facility identifier
LOCID		C	10		Landing facility location identifier
BE_LONG		I	10		Base End Longitude of the runway
BE_LAT		I	10		Base End Latitude of the runway
RE_LONG		I	10		Reciprocal End Longitude of the runway
RE_LAT		I	10		Reciprocal End Latitude of the runway
NO_RWYS		I	2		Number of runways at the landing facility
NO_PADS		I	2		Number of helicopter pads at the landing facility
SRV_LVL		C	2		Facility Service Level PR - Primary commercial service airport CM - Commercial service other than primary airport CR - Commercial service airport that also serves as a reliever airport  GA - General aviation airport RL - General aviation airport that serves as a reliever airport or heliport GP - General aviation airport that meets the criteria for a primary airport (PR), but has been declared ineligible to be a primary airport RP - General aviation airport that meets the criteria for a primary airport (PR), serves as a reliever airport, but has been declared ineligible to be a primary airport GC - General aviation airport that meets the criteria for a commercial service other than a primary airport (CM), but has been declared ineligible to be a commercial service airport
FAC_TYPE		C	1		Facility Type A - Airport H - Heliport C - Seaplane Base S - STOLport
FAC_NAME		C	42		Facility Name
CITY		C	26		City Name
RWY_ID		C	7		Runway Identification
RWY_LEN		I	5		Runway Length
RWY_WDTH		I	4		Runway Width
RWY_SFC		C	12		Runway Surface CONC - Portland cement concrete ASHP - Asphalt or bituminous concrete SNOW - Snow ICE - Ice MATS - Pierced steel planking; landing mats; membranes TREATED - Oiled; soil cement or lime stabilized GRAVEL - Gravel; cinders; crushed rock; coral or shells; slag TURF - Grass; sod DIRT - Natural soil WATER - Water G - Good Condition F - Fair Condition P - Poor Condition Note: The surface type is optionally followed by a condition indicator (e.g., ASPH-CONC, ASPH-F, ASPH-CONC-G).
RW_TRT		C	5		Runway Surface Treatment GRVD - Saw-cut or plastic grooved PFC - Porous friction course AFSC - Aggregate friction seal coat RFSC - Rubberized friction seal coat WC - Wire comb or wire tine NONE - No special surface treatment
PCN		C	11		Runway Pavement Classification Number
RWY_LTG		C	5		Runway Lights edge intensity HIGH - High MED - Medium LOW - Low NSTD - Non-standard lighting system  NONE - No edge lighting system
BE_ID		C	3		Base End Identifier
BE_TRHD		C	3		Runway base end true magnetic heading
BE_ILS		C	10		C Runway base end instrument landing system ILS - instrument landing system MLS - microwave landing system SDF - simplified directional facility LOCALIZER - localizer LDA - localizer-type directional aid ISMLS - interim standard microwave landing system ILS/DME - instrument landing system / distance measuring equipment SDF/DME - simplified directional facility / distance measuring equipment LOC/DME - localizer / distance measuring equipment LOC/GS - localizer / glide slope LDA/DME - localizer-type directional aid /distance measuring equipment
BE_AAC		C	6		Type of aircraft arresting device installed at the runway base end
BE_VGS		C	4		Visual glide slope indicators at the runway base end
BE_ALS	C		8	Approach light system at the runway base end
BE_CO	C		11	Controlling object at the runway base end
BE_COML	C		4	Designation whether the BE controlling object is marked or lighted
BE_OANA	C		5	BE Objects Affecting Navigable Airspace
RE_ID	C		3	Reciprocal End Identifier
RE_TRHD	C		3	Runway reciprocal end true magnetic heading
RE_ILS	C		10	Runway reciprocal end instrument landing system
RE_AAC	C		6	Type of aircraft arresting device installed at the runway reciprocal end
RE_VGS	C		4	Visual glide slope indicators at the runway reciprocal end S2L - 2-Box SAVASI on Left Side of Runway S2R - 2-Box SAVASI on Right Side of Runway V2L - 2-Box VASI on Left Side of Runway V2R - 2-Box VASI on Right Side of Runway V4L - 4-Box VASI on Left Side of Runway V4R - 4-Box VASI on Right Side Of Runway V6L - 6-Box VASI on Left Side of Runway V6R - 6-Box VASI on Right Side of Runway V12 - 12-Box VASI on Both Sides of Runway V16 - 16-Box VASI on Both Sides of Runway P2L - 2-Lgt PAPI on Left Side of Runway P2R - 2-Lgt PAPI on Right Side of Runway P4L - 4-Lgt PAPI on Left Side of Runway P4R - 4-Lgt PAPI on Right Side of Runway NSTD - Nonstandard VASI System PVT - Privately Owned Approach Slope Indicator Light System on A Public Use Airport that is Intended for Private Use Only  VAS - Non-Specific VASI System  NONE - No Approach Slope Light System N - No Approach Slope Light System TRIL - Tri-color VASI on Left Side of Runway  TRIR - Tri-color VASI on Right Side of Runway  PSIL - Pulsating/Steady Burning VASI on Left Side of Runway  PSIR - Pulsating/Steady Burning VASI on Right Side of Runway  PNIL - System of Panels on Left Side of Runway that May or May Not Be Lighted PNIR - System of Panels on Right Side of Runway that May or May Not Be Lighted where: SAVASI - Simplified Abbreviated Visual Approach Slope Indicator VASI - Visual Approach Slope Indicator PAPI - Precision Approach Path Indicator TRI - Tri-color Visual Approach Slope Indicator PSI - Pulsating/Steady Burning Visual Approach Slope Indicator PNI - A System of Panels Used for Alignment of Approach Slope Indicator
RE_ALS	C		8	Approach light system at the runway reciprocal end ALSAF - 3000 Foot High Intensity Approach Lighting System with Centerline Sequence Flashers. ALSF1 - Standard 2400 Foot High Intensity Approach Lighting System with Sequenced Flashers, Category I Configuration. ALSF2 - Standard 2400 Foot High Intensity Approach Lighting System with Sequenced Flashers, Category 2 Or 3 Configuration MALS - 1400 Foot Medium Intensity Approach Lighting System MALSF - 1400 Foot Medium Intensity Approach Lighting System with Sequenced Flashers MALSR - 1400 Foot Medium Intensity Approach Lighting System with Runway Alignment Indicator Lights SSALS - Simplified Short Approach Lighting System SSALF - Simplified Short Approach Lighting System with Sequenced Flashers SSALR - Simplified Short Approach Lighting System with Runway Alignment Indicator Lights NEON - Neon Ladder System ODALS - Omnidirectional Approach Lighting System LDIN - Lead-In Light System MIL OVRN- Military Overrun NSTD - All Others NONE - No Approach Lighting Is Available
RE_CO	C		11	Controlling object at the runway reciprocal end
RE_COML	C		4	Designation whether the RE controlling object is marked or lighted M - Marked L - Lighted ML - Marked And Lighted None
RE_OANA	C		5	RE Objects Affecting Navigable Airspace A(V) - Utility runway with a visual approach B(V) - Other than utility runway with a visual approach A(NP) - Utility runway with a nonprecision approach C - Other than utility runway with a nonprecision approach having visibility  minimums greater than 3/4 mile  PIR - Precision Instrument Runway
RW_ERR	C		1	A code identifying runways where the coordinate information is in some way in error

 

Rail

The Rail Network is a comprehensive database of the nation's railway system at the 1:100,000 scale. The data set covers the 48 contiguous States plus the District of Columbia. The database provides location and partial attribute information for use in national and regional network analysis applications.

Attribute Accuracy: The partial attribute list identifying 14 railroad ownership and trackage rights are based on information received from the FRA. A partial quality control evaluation of the accuracy of these attributes was performed on the database. The likelihood of attribute errors is greater in the urban than in the rural areas

The railroad ownership and trackage rights attributes are not complete. Of the 174,428 line segments in the dataset only 61,183 (approximately 35 percent) contain a value for the first railroad owner. Of 174,428 line segments, only 23,896 (less than 14 percent) contain a value for the first trackage right.

For each ASCII attribute file a corresponding dBase format attribute file is supplied. Due to the requirement for the file name extension 'dbf', the attribute file number is included in the file name prefix (RAIL100K.TL2 contains the same attributes RAIL1TL2.DBF).

Logical Consistency: The database is interconnected and is a flowable network. However, there probably are occasions where the connection between links are not exactly in the correct geographical location. There should be no redundancy of lines or nodes in the database. Initial quality control checks found no obvious under- or overshoots. The database, however, is geographically accurate, at the 1:100,000 scale

Completeness: The only attribute data included in this initial version of the 1:100,000 scale network are track ownership and trackage rights (for 14 railroads) and the State FIPS Code for the links. There are no attributes listed for Sidings. The ownership/trackage attributes were generated by conflating the FRA's 1:2,000,000 and the 1:100,000 TIGER/Line databases to the enhanced 1:100,000 DLG database.

The railroad ownership and trackage rights attributes are not complete. Of the 174,428 line segments in the dataset only 61,183 (approximately 35 percent) contain a value for the first railroad owner. Of 174,428 line segments, only 23,896 (less than 14 percent) contain a value for the first trackage right.

This version of the dataset contains no node attributes.

The sequence number (SEQ) in the ownership (RAIL100K.TL1, RAIL1TL1.DBF) and trackage rights(RAIL100K.TL2, RAIL1TL2.DBF) attribute files may not truly reflect the number of railroads having ownership or trackage rights. In some cases the data provider skipped sequence number(s). For example, LINKID = 2010 has only a single Trackage Right assigned at SEQ eight.

Horizontal Positional Accuracy: The horizontal accuracy for these data can be stated as being that associated with a 1;100,000 scale map.

Process Description: The FRARAIL and the VOLPERAIL were combined using conflation algorithms in both TransCAD and ARC/INFO. Manual adjustments were then made to the resulting spatial database.

There are five files describing rail network 1:100,000. They are RAIL100K.LNK, RAIL100K.NOD, RAIL100K.GEO, RAIL100K.TL1/RAIL1TL1.DBF, RAIL100K.TL2/RAIL1TL2.DBF. The data dictionary and file format for RAIL100K.LNK, RAIL100K.NOD, RAIL100K.GEO are the same as link file, node file and geography file as listed in Table 2. The common fields for RAIL100K.TL1/RAIL1TL1.DBF, RAIL100K.TL2/RAIL1TL2.DBF are the same as attribute file as listed in Table 1.

RAIL NETWORK 1:2,000,000

There are seven files describing the rail network 1:2,000,000. They are RAIL2M.LNK, RAIL2M.NOD, RAIL2M.GEO, RAIL2M.TL1/RAIL2TL1,DBF, RAIL2M.TL2/RAIL2TL2,DBF, RAIL2M.TL3/RAIL3TL3,DBF, RAIL2M.TN1/RAIL2MTN1,DBF. The data dictionary and file format for RAIL2M.LNK, RAIL2M.NOD, RAIL2M.GEO are the same as link file, node file and geography file as listed in Table 2. The common fields for RAIL2M.TL1/RAIL2TL1,DBF, RAIL2M.TL2/RAIL2TL2,DBF, RAIL2M.TL3/RAIL3TL3,DBF, RAIL2M.TN1/RAIL2MTN1,DBF are the same as attribute file as listed in Table 1. The other fields for RAIL2M.TL1/RAIL2TL1,DBF, RAIL2M.TL2/RAIL2TL2,DBF, RAIL2M.TL3/RAIL3TL3,DBF, RAIL2M.TN1/RAIL2MTN1,DBF are as listed from Table 17 to Table 20.

TABLE 17 RAIL2M.TL1/RAIL2TL.DBF
 

Field	Field Type	Field Width	Description
COUNTRY	C	1	Country marker
SUBSIDRR	C	4	Subsidiary railroad
PREVRR1	C	4	First previous Railroad owner
PREVRR2	C	4	Second previous Railroad owner
ABANDONED	C	1	47 Abandoned flag - link in use A - abandoned
PASS	C	3	Type of passenger rail flag - not passenger  A - Amtrak C - Commuter line T - Tourist line R - Rail line used as rapid transit V - VIA Line Y - Undesignated service Note: the field may contain more than one value
MILITARY	C	1	Military importance flag - not important C - Connector to the STRACNET S - On the STACNET system
STATE	C	2	State Postal Abbreviation
USGS_REG	C	2	X
FRA_REG	C	2	FRA Region Code
DENSITY_CO	C	5	Density Category 0.0 - unknown, abandoned, or dummy 1.0 - 0.1 to 4.9 MGTM/Mi 2.0 - 5.0 to 9.9 MGTM/Mi 3.0 - 10.0 to 19.9 MGTM/Mi 4.0 - 20.0 to 39.9 MGTM/Mi 5.0 - 40.0 to 59.9 MGMT/Mi 6.0 - 60.0 to 99.9 MGMT/Mi 7.0 - 100.0 and greater MGMT/Mi
RR_CLASS	C	1	Railroad classification
SIGNALS	C	4	Type of signaling system - unknown CTC - Centralized Traffic Control ABS - Automatic Block Sign ACS - Automatic Cab Sign ATS - Automatic Train Stop ATC - Automatic Train Control MAN - Manual, including dark (none) TTO - Time Table/Train Order
ABDYR	C	4	Abandonment Year

 

TABLE 18 RAIL2M.TL2/RAIL2TL2.DBF
 

Field	Field Type	Field Width	Description
SEQ	I	35	Owner Name sequence number
RROWNER	C	4	Owner Name Abbreviation

 

TABLE 19 RAIL2M.TL3/RAIL3TL3.DBF

(a recode table for the trackage rights railroad abbreviation)
 

Field	Field Type	Field Width	Description
SEQ	I	35	Trackage Rights sequence number
TR	C	4	Trackage Rights Railroad Name Abbreviation

 

TABLE 20 RAIL2M.TN1/RAIL2MTN1.DBF
 

Field	Field Type	Field Width	Description
NAME	C	20	Name for the node location
JUNCTION	C	5	Interchange code
STATE	C	2	US Postal Abbreviation

 

Highways

The National Highway Planning Network (NHPN) is a comprehensive network database of the nation’s principal arterial highway system and other National Highway System routes. The data set covers the 48 contiguous States plus the District of Columbia, Alaska, Hawaii, and Puerto Rico. The nominal scale of the data set is 1:100,000 with a maximal positional error of 80 meters.

Thematic Accuracy: The accuracy of the fields MILES, KM, FCLASS,SIGN1, NHS, and STRAHNET from the description section of the link table is consistent with State supplied information for the years 1992 and 1993. All other attributes in the description of the link table are unverified.

Logical Consistency: All node and link topological relationships and uniqueness of entity IDs are verified by computer algorithm

Completeness: The complete urban principal arterial system and arterials in rural areas as reported to FHWA by December 1992 are inventoried in the database. Functional classes below arterial vary on a State by State basis.

Horizontal Positional Accuracy: The elements of the NHPN have been conflated to the 1:100,000 DLG-3 data set which maintains a nominal accuracy of at least 80 meters. Where new roads have been added which are not in the DLG-3 database link alignments have been digitized or converted from digital sources acquired from State DOTs with a map scale of at least 1:100,000.

Process Description: Conflation of NHPN V1 to DLG-3 road alignments using R-MATCH software developed by the Geographic Information Systems Group, University of Tennessee. Source Used Citation Abbreviation: NHPN V1

Process Description: Integration of conflated version of NHPN V1 and assimilated State Data into a comprehensive topologically integrated network database. States edge matched and NHS attributes verified.

There are five files describing national highway planning network. They are NHPN.LNK, NHPN.NOD, NHPN.GEO, NHPN.TL1/NHPN_TL1.DBF, NHPN.TL2/NHPN_TL2.DBF. The data dictionary and file format for NHPN.LNK, NHPN.NOD, NHPN.GEO are the same as link file, node file and geography file as listed in Table 2. The common fields for NHPN.TL1/NHPN_TL1.DBF, NHPN.TL2/NHPN_TL2.DBF are the same as attribute file as listed in Table 1. The other fields are listed in Table 21 and Table 22.

TABLE 21 NHPN.TL1/NHPN_TL1.DBF
 

Field	Field Type	Filed Width	Description
SOURCE	C	1	Original source of the coordinate information S - State Supplied Digital Data U - USGS Digital Line Graphs T - US Census Tiger/Line files D - Digitized from State supplied maps M - Military Supplied data
CTFIPS	C	3	County FIPS Code
ORNL_ID	I	8	Oakridge National Lab assigned link ID
LGURB	I	3	Adjusted Urbanized Area
SMURB	I	5	Adjusted Small Urban Area
SIGN1	C	6	Composite field:  1 56 56 SIGNT1 4 57 60 SIGNN1 1 61 61 SIGNQ1
SIGN2	C	6	Composite field:  1 62 62 SIGNT2 4 63 66 SIGNN2 1 67 67 SIGNQ2
SIGN3	C	6	Composite field:  1 68 68 SIGNT3 4 69 72 SIGNN3 1 73 73 SIGNQ3
MILES	N	6	Measurement in miles
KM	N	6	Measurement in kilometers
FACTYPE	I	1	Permissible flow of traffic
TOLL	I	1	Links which have one or more toll features
LANES	I	2	Number of through lanes in both directions
ACONTROL	I	1	90 Access control to the link from adjoining roads 0 - Unknown 1 - Full Access Control 2 - Partial Access Control 3 - No Access Control
MEDIAN	I	1	Type of median  0 - Unknown 1 - Divided Highway 2 - Undivided Highway
SURFACE	I	1	Predominant surface type 0 - Unknown 1 - Paved 2 - Unpapved 3 – Ferry
FCLASS	I	2	Assigned functional class  01 - Rural Interstate 02 - Rural Principal Aterial 06 - Rural Minor Arterial 07 - Rural Major Collector 08 - Rural Minor Collector 09 - Rural Local 11 - Urban Interstate 12 - Urban Freeway or Expressway 14 - Urban Principal Arterial 16 - Urban Minor Arterial 17 - Urban Collectotr 19 - Urban Local
ACLASS	I	1	Administrative class  (blank) - Federal-Aid status unknown I - Federal-Aid Interstate P - Federal-Aid Primary S - Federal-Aid Secondary U - Federal-Aid urban N - Not on Federal-Aid System F - Direct Federal System
RU_CODE	I	1	Rural/Urban classification  1 - Rural 2 - Small Urban (1990 pop 5,000-49,999) 3 - Large Urban (1990 > 50,000)
STATUS	I	1	Describes availability to through traffic 0 - Proposed/Under construction 1 - Open to traffic
NHS	I	1	Special subnetwork for the Proposed National Highway System 0 - Not on NHS 1 - Interstate 2 - ISTEA High Priority Corridor 3 - Non-Interstate STRAHNET 4 - STRAHNET Connector 5 - ISTEA High Priority Corridor/ Non-Interstate STRAHNET 6 - ISTEA High Priority Corridor STRAHNET Connector 7 - Other NHS Note: The definition of the complete ISTEA High Priority Corridor subnetwork can be made by selecting NHPN links that have a NHS value of 2, 5, or 6
STRAHNET	I	1	Special subnetwork for the Strategic Highway Corridor Network 0 - Not on STRAHNET 1 - Non-Interstate STRAHNET link 2 - STRAHNET Priority 1 Connector 3 - STRAHNET Priority 2 Connector 4 - STRAHNET Priority 3 Connector 5 - Temporary STRAHNET Route
TRANSAM	I	1	Special subnetwork for the Trans-America corridor 0 - Not on the Trans-America corridor  1 - Trans-America corridor link Notes: The TRANSAM field describes a representation of what the Trans-America corridor could look like. At the time of documentation no Trans-America corridor has been defined. The definition of the represented corridor is due to Bruce Peterson, Oak Ridge National Laboratory

 

TABLE 22 NHPN.TN2/NHPN_TN2.DBF
 

Field	Field Type	Filed Width	Description
CTFIPS	C	3	County FIPS Code
ORNL_ID	I	7	Oakridge National Lab assigned link ID
LGURB	I	3	Three digit HPMS Urbanized Area code
SMURB	I	5	Five digit CENSUS Adjusted Small Urban Area Code
BNDRY	I	2	To designate boundary node

Airways

The Commercial Air Segment Network is a comprehensive point-to-point network database of the nation's commercial air segment network. The data set covers point-to-point segment information between commercial airports within the 48 contiguous States plus Alaska, Hawaii, and US territories. The data provide users with service information about commercial air segments between commercial airports primarily for national planning applications.

Attribute Accuracy: Attributes were derived from the U.S. Department of Transportation, Office of Airline Statistics (OAI), annual summary of monthly T-100 reports of domestic certified air carriers

Logical Consistency: Each air segment record is a straight line connecting pairs of points representing the locations of commercial U.S. airports. Each segment represents a direct, non-stop commercial air route between the two end points.

Completeness: The air segments are complete for large U.S. certified air carriers. Data on foreign flag air carriers is protected from public disclosure by international agreement and has been excluded from this database. Data on commuter airlines is not reported in the T-100 reports, and has also been excluded from this database.

Horizontal Positional Accuracy: Accuracy of the digital node data is based upon the accuracy of the airport locations as defined in the metadata for Public-Use Airports. The link information is not intended to represent actual flight patterns and is not positionally accurate.

The airport points should carry the same longitude and latitude values as the airway segment endpoints (carrying the LOCID as FEATURID to match the points and nodes). In most cases they do. The longitude and latitude value for Denver International Airport (DEN) does not match the value for the associated node.

Airport longitude, latitude point = -104.667002, 39.858408

Airway node longitude, latitude = -104.879755, 39.774292

Process Description: Monthly reports were totaled to produce an annual summary of flights, seats, and enplaned passengers, by direction. Segment endpoints were matched against public use airports using landing facility's location identifier (LOCID) to obtain the end point locations.

There are five files describing commercial airways. They are AIRWAY.LNK, AIRWAY.NOD, AIRWAY.GEO, AIRWAY.TL1/AIRWAYL1.DBF, AIRWAY.TL2/AIRWAYL2.DBF. The data dictionary and file format for AIRWAY.LNK, AIRWAY.NOD, AIRWAY.GEO are the same as link file, node file and geography file as listed in Table 2. The common fields for AIRWAY.TL1/AIRWAYL1.DBF, AIRWAY.TL2/AIRWAYL2.DBF are the same as attribute file as listed in Table 1. The other fields are listed in Table 23 and Table 24.
 
 

TABLE 23 AIRWAY.TL1/AIRWAYL1.DBF
 

Field	Field Type	Field Width	Description
SEATS1TO2	I	10	Number of passenger seats
SEATS2TO1	I	10	Number of passenger seats
TOTSEAT	I	10	Total number of passenger seats
PASS1TO2	I	10	Number of passengers
PASS1TO1	I	10	Number of passengers
TOTPASS	I	10	Total number of passengers
SCHFLT1TO2	I	10	Number of scheduled flights
SCHFLT2TO1	I	10	Number of scheduled flights
TOTSCHFLT	I	10	Total number of scheduled flights
ACTFLT1TO2	I	10	Actual number of scheduled flights
ACTFLT2TO1	I	10	Actual number of scheduled flights
TOTACTFLT	I	10	Total Actual number of scheduled flights

 

TABLE 24 AIRWAY.TL2/AIRWAYL2.DBF

- Recode table for Air Carrier Names
 

Field	Field Type	Field Width	Description
SEQ_NUM	I	2	Sequence Number
CARRIER	C	25	Full Air Carrier Name

 

Polygon Features

Bureau of Economic Analysis (BEA) Areas

The BEA Economic Areas database is a geographic polygon database representing county based economic regions for the United States. The database provides locational information for use in national and regional cartographic and spatial analysis applications.

Process Description: Adjoining counties which comprise the BEA regions were merged into unique polygons.

There are two files describing BEA regions: BEA.ARE and BEA.GEO. The data dictionary and file format are as same as area file and geography file as listed in Table 2.

Congressional Districts

The 104th Congressional District Boundaries database is a geographic database of political boundaries for the 104th Congressional districts. The data provide users with information about the locations of congressional districts, primarily for national planning applications.

Process Description: individual files for the Congressional Districts in Alaska, Hawaii, Puerto Rico, and the 48 contiguous states were merged into a single dataset.

There are two files describing 104^th congressional district boundaries: CD104.ARE and CD104.GEO. The data dictionary and file format are as same as area file and geography file as listed in Table 2.

Counties

The United States County Boundaries database is a geographic database of county political boundaries integrated with shorelines in the United States containing information on location, identification, and size. The database includes boundaries for all 50 states. The data provide users with information about the locations, names, FIPS Codes, and size of counties primarily for national planning applications.

Attribute Accuracy: Attributes for the County Boundary database have been created using a Geographic Information System. All area and distance calculations are calculated to the nearest 50m.

Logical Consistency: All node-link and polygon topological relationships are created and verified using computer algorithms. Uniqueness of entity IDs are similarly verified by computer algorithm.

Horizontal Positional Accuracy: The positional accuracy of each data set varies as described. The County borders database was compiled from TIGER/Line data with a corresponding positional accuracy of +/- 80m for the contiguous 48 States plus Washington DC and Hawaii. TIGER lines for Alaska are at a scale of 1:250,000. The shorelines for the 23 coastal states were created using 1:250,000 NOS digital data which has a positional accuracy of +/- 200m. Thus, all internal political boundaries have a higher accuracy than do the coastal definitions with the exception of Alaska.

Process Description: All state supplied maps were digitized using ARC/INFO V6.1x. All State supplied digital data was converted to ARC/INFO using a variety of encoding methods. The state databases were appended and adjusted to correct minor geodetic problems. County boundaries were added from TIGER/Line data and topologically integrated using ARC/INFO. After attributes were added and the data set checked for completeness and accuracy it was extracted from ARC/INFO and reformatted into ASCII data files.

All county political boundaries were extracted from the TIGER/Line CD-ROMs and appended into a single polygon database using ARC/INFO V6.1x. The NOS vectors were overlaid and topologically integrated into the county polygons using ARC/INFO. After attributes were added and the data set checked for completeness and accuracy it was extracted from ARC/INFO and reformatted into ASCII data files.

There are three files describing county boundaries: COUNTY.ARE, COUNTY.GEO and COUNTY.T01/COUNTY.DBF. The data dictionary and file format for COUNTY.ARE, COUNTY.GEO are as same as area file and geography file as listed in Table 2. The common fields for COUNTY.T01/COUNTY.DBF are as same as attribute file listed in Table 1. The additional fields are summarized in Table 25.

TABLE 25 COUNTY.T01/COUNTY.DBF
 

Field	Field Type	Field Width	Description
SOURCE	C	1	Source of the County name
SQMILES	N	10	Approximate county area in square miles
SQKM	N	10	Approximate county are in square kilometers

 

Federal Aid Urbanized Areas

The Federal Aid Urbanized Area Boundaries database is a geographic database of Federal-aid boundaries for urban areas with a population greater than 50,000. The database includes boundaries for urban areas in all 50 states, the District of Columbia, and Puerto Rico. The data provide users with information about the locations, names, urban, census and FIPS codes, and size of urban areas primarily for national planning applications.

Attribute Accuracy: Attributes for the Adjusted Urbanized Area database are created in a consistent manner with a similar tolerance. Other attributes in the Adjusted Urbanized Area database were taken from the Highway Performance Monitoring System Field Manual Appendix B. All area and distance calculations are calculated to the nearest 50m.

Logical Consistency: All node-link and polygon topological relationships are created and verified using computer algorithms. Uniqueness of entity IDs are similarly verified by computer algorithm.

Completeness Report: 399 distinct Adjusted Urbanized Areas (AUB) are identified database. Six (6) Urbanized areas are enclosed within the boundaries of other AUBs and are not defined.

Horizontal Positional Accuracy: The positional accuracy of each data set varies as described. The Adjusted Urbanized Area database was created from data which had scale of 1:100,000 or better and as such has a positional accuracy of +/- 80m. The shorelines for the 23 coastal states were created using 1:250,000 NOS digital data which has a positional accuracy of +/- 200m. Thus, all internal political boundaries have a higher accuracy than do the coastal definitions with the exception of Alaska.

There are three files describing federal urbanized area boundaries: FHWA_UZA.ARE, FHWA_UZA.GEO and FHWA_UZA.T01/FHWA_UZA.DBF. The data dictionary and file format for FHWA_UZA.ARE, FHWA_UZA.GEO are as same as area file and geography file as listed in Table 2. The common fields for FHWA_UZA.T01/FHWA_UZA.DBF are as same as attribute file listed in Table 1. The additional fields are summarized in table 26.

TABLE 26 FHWA_UZA.T01/FHWA_UZA.DBF
 

Field	Field Type	Field Width	Description
SOURCE	C	1	Describes the original source of the NAME attribute data in the polygon record
SQMILES	N	12	An approximation of the area of the polygon in square miles
SQKM	N	12	An approximation of the area of the polygon in square kilometers
NAME	C	4	A descriptive name for the polygon feature
CENCODE	I	4	The Census assigned Urbanized Area Code for the adjusted urbanized area

 

Metropolitan Statistical Areas (MSA)

The United States MSA Boundaries database is geographic database of metropolitan statistical area boundaries in the United States containing information on location, identification, and size. The database includes boundaries for all 50 states. The data provide users with information about the locations, names, and sizes of MSAs primarily for national planning applications.

Process Description: All state supplied maps were digitized. MSA boundaries were added from TIGER data and topologically integrated. The data set was checked for completeness and accuracy and was extracted and reformatted into ASCII data files.

All MSA political boundaries were extracted from the TIGER/Line files and appended into a single polygon database.

There are three files describing metropolitan statistical area boundaries: MSA.ARE, MSA.GEO and MSA.T01/MSA.DBF. The data dictionary and file format for MSA.ARE, MSA.GEO are as same as area file and geography file as listed in Table 2. The common fields for MSA.T01/MSA.DBF are as same as attribute file listed in Table 1. The additional fields are summarized in Table 27.
 
 

TABLE 27 MSA.T01/MSA.DBF
 

Field	Field Type	Field Width	Description
FULLNAME	C	24	The full Metropolitan Statistical Area Name

 

National Transportation Analysis Regions (NTAR)

National Transportation Analysis Regions (NTAR) divide the U.S. into 89 areas that delineate the functional geography transportation demand. NTARs are aggregates of the Bureau of Economic Analysis (BEA) Economic Areas and were defined by the DOT for use in the 1993 Commodity Flow Survey (CFS).

There are two files describing national transportation analysis regions: NTAR.ARE and NTAR.GEO. The data dictionary and file format are as same as area file and geography file as listed in Table 2.

Parks

National park boundaries database is variable scale boundaries for selected National Parks, Recreation Areas, Seashores, Military Parks Historical Areas, and Monuments in the United States and territories. The database provides locational and attribute information for use in national and regional cartographic and spatial analysis applications.

Notes: This Park Boundaries file is the result of an immediate need for this type of data in several GIS databases being setup in the National Park Service. These digital boundaries represent the "best guess" and data that could be collected in a short time.

This data is not an "official" distribution by the National Park Service, but is only provided to assist those persons who require something to work with. Only 348 parks out of the current 368 are represented in this data set. Although every attempt has been made to find errors and correct them it is probable that some still exist. The boundaries are not necessarily the most up-to-date and the acreage and other attributes may be incorrect.

This coverage was assembled from many other existing databases and any errors digitized or keyed in at those sites may still exist in this composite. The individual boundaries were collected when possible from Parks that maintain their own GIS databases, digitized from existing 1:24000 scale USGS quadrangles, and various other maps ranging in scale from 1:360 to 1:2,000,000. The dates from these sources range from 1965 to the present and do not necessarily reflect all boundary changes that have occurred during this time period.

Of the original 348 parks represented, 23 of them are shown with 2 meter square boxes. Good digitized boundaries for these parks have not been located yet but, we do have a point location within them. The boxes were used to keep this coverage a strictly polygon coverage instead of mixing points in with it.

The coverage is based on the Albers Equal Area projection for the continental US and uses the USGS's coordinate system for the 1:2,000,000 National Atlas. The ARC/INFO "describe" command will detail the projection. Those park service units that are outside the continental US are not shown well in this projection, but it was simpler to maintain a single coverage of all parks. Those parks with a "calculated" area of only 4 meters are the point locations referred to above.

Process Description: The NPS National Park Boundary file was merged with the United States State Boundary file to create a National Park Boundary file by state.

There are three files describing national parks boundaries: PARK.ARE, PARK.GEO and PARK.T01/PARK.DBF. The data dictionary and file format for PARK.ARE, PARK.GEO are as same as area file and geography file as listed in Table 2. The common fields for PARK.T01/PARK.DBF are as same as attribute file listed in Table 1. The additional fields are summarized in Table 28.

TABLE 28 PARK.T01/PARK.DBF
 

Field	Field Type	Field Width	Description
PNAME	C	40	Park Name
PAREA	N	12	Park Area
CLASS	I	1	Clean Air Act classification level
REGION	C	18	NPS Region
SNR	I	1	Significant Natural Resource Indicator
GEOG	C	4	Geographic Location of the Park
LABEL	I	1	Label to identify main park polygon
SCALE	C	10	Scale at which the boundary was digitized
DATE	I	4	Year the boundary was digitized
SOURCE	C	20	Source map from which the boundary was digitized
ST_NAME	C	25	State Name in which the park polygon is located
STATECODE	C	2	State Postal Code abbreviation

 

United States State Boundaries

The United States State Boundaries database is a geographic database of state political boundaries integrated with shorelines in the United States containing information on location, identification, and size. The database includes boundaries for all 50 states, the District of Columbia, and Puerto Rico. The data provide users with information about the locations, names, FIPS Codes, and size of states primarily for national planning applications.

Attribute Accuracy: Attributes for the State Boundary database have been created using a Geographic Information System. All area and distance calculations are calculated to the nearest 50m.

Logical Consistency: All node-link and polygon topological relationships are created and verified using computer algorithms. Uniqueness of entity Ids are similarly verified by computer algorithm.

Horizontal Positional Accuracy: The positional accuracy of each data set varies as described. The State borders database was compiled from TIGER/Line data with a corresponding positional accuracy of +/- 80m for the contiguous 48 States plus Washington D.C and Hawaii. TIGER/Line files for Puerto Rico and Alaska are at a scale of 1:125,000. The shorelines for the 23 coastal states were created using 1:250,000 NOS digital data which has a positional accuracy of +/- 200m. Thus, all internal political boundaries have a higher accuracy than do the coastal definitions with the exception of Puerto Rico and Alaska.

Process Description: All state supplied maps were digitized using ARC/INFO V6.1x. All State supplied digital data was converted to ARC/INFO using a variety of encoding methods. The state databases were appended and adjusted to correct minor geodetic problems. State boundaries were added from TIGER/Line data using and topologically integrated using the ARC/INFO GIS. After attributes were added and the data set checked for completeness and accuracy it was extracted from ARC/INFO and reformatted into ASCII data files.

All state political boundaries were extracted from the TIGER/Line CD-ROMs and appended into a single polygon database using ARC/INFO V6.1x. The NOS vectors were overlaid and topologically integrated into the state polygons using ARC/INFO. After attributes were added and the data set checked for completeness and accuracy it was extracted from ARC/INFO and reformatted into ASCII data files.

There are three files describing state boundaries: STATE.ARE, STATE.GEO and STATE.T01/STATE.DBF. The data dictionary and file format for STATE.ARE, STATE.GEO are as same as area file and geography file as listed in Table 2. The common fields for STATE.T01/STATE.DBF are as same as attribute file listed in Table 1. The additional fields are summarized in Table 29.

TABLE 29 STATE.T01/STATE.DBF
 

Field	Field Type	Field Width	Description
SOURCE	C	1	Source of State name
SQMILES	N	12	Approximate state area in square miles
SQKM	N	12	Approximate state area in square kilometers
NAME	C	25	State Name

Examples of how data may be used to support state, metropolitan and transit agencies for transportation planning

The National Transportation Atlas Database (NTAD) is mainly used at the national level to conduct nationwide studies (2, 5). The database is also widely used as a regional network for state and metropolitan freight planning purposes (2, 3, 4). The database can be used for multimodal planning efforts as well (1, 3). In most states and metropolitan planning organizations, this database is not explicitly used. They mainly use it to crosscheck their own database or make state-by-state comparisons.

(I think the large transit agencies are using national/regional transit network/facilities database to do their transit planning. These databases are part of NTAD. No paper is found.)

1. Daniel Rice, F. Gerald Rawling, Marietta Bailey, et al, " Using geographic information systems for intermodal planning in Chicago region", Transportation Research Board, January 7-11, 1996.

This paper describes the development and application of a geographic information system as a planning tool in support of intermodal planning for the Chicago region. This planning level is based on Tiger/Line files, and provides a mechanism to track geographic relationships as well as serving as an analytical tool in the decision making process. The National Transportation Atlas databases (NHPN v2.0 and FRA 1:2,000,000) appear to offer useful information which would enhance the Tiger-based database to generate industry feedback.

2. Venkatesh Krishnan, and Kathleen Hancock " Highway freight flow assignment in Massachusetts using geographic information systems", Transportation Research Board, January 10-14, 1998.

The primary objective of this research is to develop a GIS-based approach for distributing and assigning freight flows in Massachusetts. An intermediate goal is to develop a quantitative methodology for estimating freight traffic on major roads in Massachusetts from newly released inter-state commodity flow data. The highway network was extracted from the National Transportation Atlas Databases (NTAD) and consisted of the National Highway Planning Network State, US and Interstate highways in Massachusetts.

3. Mohammed Alam, and Edwards Fekpe " Application of GIS-T in freight data analysis: a case study of I-90/I-94 corridor analyses", Transportation research Board, January 1998. OH

The National Highway Planning Network (NHPN) is used as the spatial network to support the GIS-T analysis. This paper is directed towards demonstrating certain integration techniques in GIS to analyze freight flow characteristics. Such analyses include location of transportation facilities and freight generators; variation of truck traffic mix by configuration and body type; truck traffic flow map; and travel time contours. These are important for freight transport policy review and assessment.

4. "Statewide Freight Transportation Planning Model and Methodology Development Program" by CTRE.

NTAD railroad and primary highway networks are used to build the project network. The goal of this project is to develop a tactical model of freight transportation demand in Iowa that will consider all modes of transportation as well as the most important commodities. The tool is capable of providing priority listings of state roads and their importance to various industry sectors.

5. Chin S. M. and Peterson B: National highway planning network "GIS applications for national transportation data", GIS-T proceeding 1990. (only abstract available)

National Highway Planning Network (NHPN) is described as one of the GIS databases in this paper. Detailed lists of elements are presented in this paper so that the potential users can assess the usefulness of these systems to their own applications.

Notes on Correspondence

1. E-mail message from Southworth.

The national highway and rail networks have been used by FHWA in their truck weight studies. Recommend contacting Karen White in FHWA.

2. E-mail message from Southworth.

The national networks were used in the studies carried out in Oak Ridge National laboratory. a)Multimodal travel of the 1993 flooding in the Midwest; b) I-75 corridor access.

3. Middendorf et al , Transportation Research Forum 1995 37^th proceedings p456-473.

4. E-mail message from Southworth.

Bill Black of Indiana University used it. Recommend to contact Bruce Spear in BTS.

5. Transportation Research Forum this year.

Using the national networks for freight modeling

6. Telephone contacts from Connecticut DOT.

NTAD is not used.

7. GIS-T proceeding 98 by Southworth.

8. E-mail message from Puget Sound MPO and Washington DOT.

Not too much use of NTAD. They only use it for cross-checking network elements. They want to explore more.

9. E-mail message from Georgia DOT.

They rarely use NTAD or NORTAD except when using this data to make state-to-state comparisons. They supplied much of this data for Georgia.

Potential Use of Database

Nationwide analysis of congested airports

CTRE is an Iowa State University center.

Contact CTRE, 2901 South Loop Drive, Suite 3100, Ames, Iowa 50010-8632
Phone  515-294-8103 ~ Fax 515-294-0467

CTRE communications Marcia Brink ~ CTRE webmaster Michele Regenold

www.ctre.iastate.edu/