Connecticut Airports is a 1:24,000-scale, feature-based layer that includes airport features on the U.S. Geological Survey (USGS) 7.5 minute topographic quadrangle maps for the State of Connecticut. This layer only includes features located in Connecticut. The layer is based on information from USGS topographic quadrangle maps published between 1969 and 1984 and does not represent airports in Connecticut at any one particular point in time. The layer does not depict current conditions and excludes airports that have been built, modified, or removed since the time these topographic quadrangle maps were published. The layer delineates airports, heliports and seaplane landing areas. It does not include airport name, airport code, airport elevation, flight schedule, runway capacity, or ownership information. Features are linear and generally depict landing strips and perimeters for large and small airports. Attribute information is comprised of codes to cartographically represent (symbolize) these features on a map. This layer was originally published in 1994. The 2005 edition includes the same airport features published in 1994, but the attribute information has been slightly modified and made easier to use.
Connecticut Airports is 1:24,000-scale base map data. It depicts the location of all airports published on the USGS topographic quadrangle maps. For base map purposes, use this layer with other 1:24,000-scale base map data such as Hydrography, Roads and Trails, Railroads, and Towns. The Airports layer includes information within Connecticut and is derived from the Airports Master layer, which includes all airport features depicted on all of the U.S. Geological Survey (USGS) 7.5 minute topographic quadrangle maps that cover the State of Connecticut. Not intended for maps printed at map scales greater or more detailed than 1:24,000 scale (1 inch = 2,000 feet.). This layer is largely cartographic in nature since it does not include specific information about individual airports.
In 2004, the State of Connecticut Department of Environmental Protection developed automated procedures to systematically maintain feature topology and attribute integrity for a set of related transportation data produced by the agency during the 1980's and 1980's from the 1:24,000-scale USGS DLGs. These layers include Roads and Trails Master, Roads and Trails, Railroads Master, Railroads, Buffered Roads Master, Buffered Roads, Airports Master, and Airports. Automated procedures were developed using ArcInfo Workstation 8.3 software and the Arc Macro Language (AML) as a scripting environment and recorded in an AML file named MAKECOVER.AML for the transportation category of data for the State of Connecticut, Department of Environmental Protection. For additional information related to the original source of data from the U.S. Geological Survey, refer to the Data User Guides and Standards for 1:24,000-Scale Digital Line Graphs and Quadrangle Maps available from the U.S. Geological Survey, National Mapping Program.
Publication dates of the USGS 7.5 minute topographic quadrangle maps for the State of Connecticut through 1984.
No restrictions or legal prerequisites for using the data. The data is suitable for use at appropriate scale, and is not intended for maps printed at scales greater or more detailed than 1:24,000 scale (1 inch = 2,000 feet). Although this data set has been used by the State of Connecticut, Department of Environmental Protection, no warranty, expressed or implied, is made by the State of Connecticut, Department of Environmental Protection as to the accuracy of the data and or related materials. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the State of Connecticut, Department of Environmental Protection in the use of these data or related materials. The user assumes the entire risk related to the use of these data. Once the data is distributed to the user, modifications made to the data by the user should be noted in the metadata. When printing this data on a map or using it in a software application, analysis, or report, please acknowledge the State of Connecticut, Department of Environmental Protection and the U.S. Geological Survey, National Mapping Program as the source for this information. For example, include the following data source description when printing this layer on a map: Airports - From the Airports layer, compiled and published by CT DEP and USGS. Source map scale is 1:24,000.
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The layer retains the feature types identified by the USGS. All attributes have valid values. Values are within defined domains. The accuracy test for the APARC_COD attribute values was conducted by comparing the airports published on the source topographic quadrangle maps with 1:24,000-scale check plots or interactive displays of the airports data on a computer graphic system. These checkplots and computer displays depicted airport features in different colors based on their respective APARC_COD values for comparison with the paper quadrangle maps. The APORTCLASS and AV_LEGEND attribute values are based on APARC_COD values. APORTCLASS decodes the APARC_COD field. AV_LEGEND is a simple classification of APARC_COD values. The APORTCLASS and AV_LEGEND fields were populated though table joins to lookup tables. These values were not manually entered.
Line features conform to the following topological rules. Lines are single part. There are no duplicate lines. Lines do not self overlap. Lines do not overlap other lines. Lines intersect only at nodes, and nodes anchor the ends of all lines. Lines do not overshoot or undershoot other lines they are supposed to meet and intersect. The tests of logical consistency were performed by the USGS PROSYS program, and subsequently by the State of Connecticut using ESRI ArcInfo software to maintain feature topology in ArcInfo coverage format. The data is topologically clean. The ArcInfo Clean function was repeatedly used following edits to verify topology and enforce a minimum distance between vertices of 4 feet (fuzzy tolerance) and a minimum allowed overshoot length of 10 feet (dangle length).
The completeness of the data reflects the USGS National Mapping Division standards for feature content of the data sources, which are the Large Scale (7.5 minute) Digital Line Graph (DLG) files available from the USGS. For Connecticut, the Large Scale DLG files used to create this layer are for the 1:24,000-scale topographic quadrangle maps published between 1969 and 1984. The Airports layer is complete in the sense that it accurately reflects the contents of the most recently published USGS topographic quadrangle maps available at the time the State of Connecticut, Department of Environmental Protection began creating the layer. Some newer quadrangle maps have been published by the USGS since 1984, however, the State of Connecticut did not incorporate this information into the Airports layer. So compared to the most recent set of topographic quadrangle maps available today, the Airports layer is incomplete, and substantially incomplete when compared to airports in existence today. This data is not updated.
This data complies with United States National Map Accuracy Standards for 1:24,000 scale maps. According to this standard, not more than 10 percent of the points tested are to be in error by more than 1/50 inch (40 feet) measured on the publication scale of a USGS 7.5 minute topographic quadrangle map.
USGS Large Scale Digital Line Graph (DLG) data are digital representations of the cartographic (base map) information published on the 1:24,000-scale, 7.5 minute topographic quadrangle maps. The USGS produces DLG data per 7.5 minute quadrangle. DLG data is organized into categories such as hydrography, boundaries, and transportation. At the time the State of Connecticut began developing the Airports layer in the late 1980's, Large Scale DLG files were available for 112 of the 115 topographic quadrangle maps necessary to cover Connecticut. Large Scale DLG files were not available for the West Springfield Mass-Conn, Springfield South Mass-Conn, and Hamden Mass-Conn quadrangle. It is important to note that the Large-Scale DLGs were produced in the 1980's at a time when the USGS was developing standards, conventions, and procedures to convert topographic quadrangle maps into digital spatial data. The Connecticut DLG files were produced by digitizing from stable-base mylars using a digitizing tablet to capture the digital data. The features were manually digitized and attributed. Today, there are other methods available for producing DLGs. For additional DLG documentation, refer to the Data User Guides and Standards for 1:24,000-Scale Digital Line Graphs and Quadrangle Maps available from the U.S. Geological Survey, National Mapping Program.
Airport features for each quadrangle map.
Airport features for Connecticut combined in a single, statewide layer. Airport is in ArcInfo Coverage format.
Airport features for Connecticut combined in a single, statewide layer. Airport.shp is in Shapefile format.
Airport features for Connecticut combined in a single, statewide layer. Airport is in GeoDatabase Feature Class format.
DLG to ArcInfo coverage format conversion - Using ESRI ArcInfo software, the State of Connecticut, Department of Enviromental Protection converted the Airports overlay from the Transporation category for each Large Scale DLG file to ArcInfo Coverage format, resulting in one ArcInfo Coverage of linear features for each quadrangle area. The Transportation category of data includes major transportation systems collected in three separate overlays labeled: (1) Roads and Trails, (2) Airports, and (3) Pipelines, Transmission Lines, and Miscellaneous Transportation Features. Only the Airport overlay was extracted from the Transportation Layer as a data source for this layer. Each Coverage was converted from UTM to Connecticut State Plane, North American Datum of 1927 (NAD27).
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Attribute value verification - The quality and accuracy of the digitizing and coding of the airport features was checked by comparing the transporation features in each ArcInfo Coverage with the airport features on the published USGS topographic quadrangle maps. Visual comparisons using 1:24,000 scale paper check plots combined with automated procedures to identify inconsistent attribute coding were the primary means of evaluating and correcting obvious errors with the original DLG data. Where necessary, corrections were made to DLG major and minor codes in the ArcInfo Coverages. The original DLG major and minor codes were modified to form the APARC_COD attribute in the final Airports layer.
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Quadrangle coverage edgematch - Using ESRI ArcInfo software, the individual 7.5 minute quadrangle coverages of Airports features were systematically edgematched. Features along the edges of adjacent quadrangle were moved to make their end-point coordinates identical through a process of checkerboard style edgematching. Features on every other quadrangle were adjusted. The ends of Airport features were snapped to align with the connecting stationary features on adjacent quadrangles if their end-points were generally within 20 feet. Only a few airports appear on more than one topographic quadrangle map so only a few quadrangles were edgematched. On occasion, there were no connecting features on adjacent quadrangles to match to so some features abruptly end at quadrangle boundaries. This is either due to deficiencies with the data source or variations in quadrangle publication dates. These deficiencies were not resolved because the intent was to represent the classification of these features on USGS topographic quadrangle maps.
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Statewide layer creation - Using ESRI ArcInfo sofware, all of individual 7.5 minute quadrangle coverages were appended to form a single, statewide Airports layer. Linear features were unsplit (merged) to eliminate unnecessary pseudo nodes between similar features from adjacent quadrangle areas. Final line feature topology was established with ArcInfo Fuzzy and Dangle tolerances verified at 4 and 10 feet, respectively. At this step in the process the Airports layer was fully attributed and ready for use. Not all data fields from the orginal DLG files were preserved by this step in the process. A new data field, AV_LEGEND, was added to more easily classify and cartographically represent features when displaying the information with software such as ArcView.
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Datum conversion - Using ESRI ArcInfo software, the Airports layer was converted from the Connecticut State Plane Coordinate System of 1927 (NAD27) to the Connecticut State Plane Coordinate System of 1983 (NAD83). The NADCON (North American Datum CONversion) data transformation was used.
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Attribute enhancements - APORTCLASS and AV_LEGEND attributes were changed from storing abbreviated values in upper case (e.g. AIRPORT, HELIPORT, SEAPLANE) to full length values in both upper and lower case (e.g. Airport, Heliport, Seaplane). The following attributes from the original DLG files were removed from the data table due to poor data quality: PHOTRV_FLG and QUAD_NO. These attribute values were inconsistent, not verified and of limited value to the State of Connecticut. Using Arc Macro Language (AML), an automated process (MAKECOVER.AML) was developed to maintain consistent attribute values by programmatically joining lookup data tables to decode numeric code fields. The MAKECOVER.AML also created this particular copy of the Airports layer that is clipped to the State of Connecticut boundary.
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Create 2005 Edition of Airport - The automated process (software program), MAKECOVER.AML, developed for the previous process step was executed in 2005 in order to create a 2005 edition (copy) of Airport that captures recent corrections and enhancements made to the layer. The MAKECOVER.AML program was last run in 2005, and the name of the resulting ArcInfo coverage created by this automated process is AIRPORT. Note, this particular run of the MAKECOVER.AML created a copy of the Airport ArcInfo coverage that is clipped to the State of Connecticut boundary and is named AIRPORT instead of AIRPORTMASTER. Prior to 2005, the Airports layer in ArcInfo Coverage format that was clipped to the state of Connecticut boundary was named AIRPORTCT.
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Export to Shapefile format - Converted line feature data from an ArcInfo coverage named AIRPORT to a Shapefile named Airport.shp. Excluded the FNODE#, TNODE#, LPOLY#, RPOLY#, LENGTH, AIRPORT#, AIRPORT-ID attributes from the Shapefile because their values are only maintained by ArcInfo software with spatial data that is ArcInfo coverage format.
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Convert to GeoDatabase Feature Class format - Defined new Feature Class named Airport; and imported the attribute definitions, loaded features and imported metadata from Airport.shp shapefile. Spatial Reference Properties for Feature Class: Coordinate System: NAD_1983_StatePlane_Connecticut_FIPS_0600_Feet XY Domain MinX: 100000; MaxX: 2247483.645 XY Domain MinY: 200000; MaxY: 2347483.645 Precision: 1000
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Internal feature number.
ESRI
Feature geometry.
ESRI
Airport Arc Code. Numeric values that identify airport feature types.
State of Connecticut, Department of Environmental Protection
Landing Strip, Airport, Perimeter of Airport
CT DEP, USGS
Heliport, Perimeter of Heliport
CT DEP, USGS
Seaplane Ramp or Landing Area
CT DEP, USGS
Airport Class. Text values that correspond to the numeric APARC_COD attribute values. APORTCLASS is the English language equivalent of (decodes) the APARC_COD field
State of Connecticut, Department of Environmental Protection
ArcView Legend. Text field for symbolizing airport feature types on a map.
State of Connecticut, Department of Environmental Protection
This category includes APARC_COD value 403.
CT DEP
This category includes APARC_COD value 404.
CT DEP
This category includes APARC_COD value 407.
CT DEP
Includes linear airport features such as includes airports, heliports and seaplane landing areas published on the U.S. Geological Survey 7.5 minute topographic quadrangle maps. Information encoded about features includes airport feature type classification and one standard symbology classification schemes.
For additional information related to the original source of data from the U.S. Geological Survey, refer to the Data User Guides and Standards for 1:24,000-Scale Digital Line Graphs and Quadrangle Maps available from the U.S. Geological Survey, National Mapping Program.
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Although this data set has been used by the State of Connecticut, Department of Environmental Protection, no warranty, expressed or implied, is made by the State of Connecticut, Department of Environmental Protection as to the accuracy of the data and or related materials. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the State of Connecticut, Department of Environmental Protection in the use of these data or related materials. The user assumes the entire risk related to the use of these data. Once the data is distributed to the user, modifications made to the data by the user should be noted in the metadata.
The data distributor does not provide custom GIS analysis or mapping services. Data is available in a standard format and may be converted to other formats, projections, coordinate systems, or selected for specific geographic regions by the party receiving the data.
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