Connecticut Roads and Trails is a 1:24,000-scale, feature-based layer that includes road and trail 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 the road network in Connecticut at any one particular point in time. The layer does not depict current conditions and excludes many roads that have been built, modified, or removed since the time these topographic quadrangle maps were published. The layer includes Interstate highways, US routes, state routes, local roads, unpaved roads, traffic circles, bridges, cul-de-sacs, trails, etc. It does not include route number, street name, house address, traffic direction, or traffic volume information for these features. Nor does it represent a complete or current network of hiking trails. Features are linear and represent road centerlines. Attribute information is comprised of codes to cartographically represent (symbolize) road and trail features on a map. This layer was originally published in 1994. The 2005 edition includes the same road features published in 1994, but the attribute information has been slightly modified and made easier to use.
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.
Roads and Trails as line features (Source: State of Connecticut, Department of Environmental Protection and U.S. Geological Survey, National Mapping Program)
Internal feature number. (Source: ESRI)
Feature geometry. (Source: ESRI)
Road Arc Code. Numeric values that identify road types. (Source: State of Connecticut, Department of Environmental Protection)
| Value | Definition |
|---|---|
| 5 | Cul-De-Sac |
| 201 | Primary Route, Class 1, Undivided |
| 202 | Primary Route, Class 1, Divided |
| 203 | Primary Route, Class 1, Separated |
| 204 | Primary Route, Class 1, One Way |
| 205 | Secondary Route, Class 2, Undivided |
| 206 | Secondary Route, Class 2, Divided |
| 207 | Secondary Route, Class 2, Separated |
| 209 | Road or Street, Class 3 |
| 210 | Road or Street, Class 4 |
| 211 | Trail, Class 5, other than Four Wheel Vehicles |
| 212 | Trail, Class 5, Four Wheel Vehicles |
| 213 | Footbridge |
| 214 | Ferry Crossing |
| 215 | Perimeter Of Parking Area |
| 217 | Road Or Street, Class 3, Divided |
| 218 | Road Or Street, Class 3, Separated |
| 401 | Traffic Circle |
| 402 | Cloverleaf or Interchange |
| 403 | Toll Plaza |
| 405 | Non-Standard Section Of Road |
| 604 | Road Under Construction, Class Unknown |
| 613 | In Service/Rest Area |
| 401201 | Traffic Circle, Class 1 |
| 401205 | Traffic Circle, Class 2 |
| 401209 | Road or Street, Class 3 |
| 402201 | Cloverleaf, Class 1 |
| 601202 | Tunnel, Class 1 |
| 604203 | Road Under Construction, Class 2 |
| 605210 | Old Railroad Grade, Road Or Street, Class 4 |
| 605211 | Old Railroad Grade, Trail, Class 5 |
| 610205 | Private Road, Class 2 |
| 610209 | Road or Street, Class 3 |
| 610210 | Private Road, Class 4 |
| 618201 | Primary Route On Drawbridge, Class 1, Undivided |
| 618205 | Secondary Route On Drawbridge, Class 2, Undivided |
| 618209 | Road or Street, Class 3 |
| 621201 | Connector, Class 1 |
Road Class. Text values that correspond to the numeric ROARC_COD attribute values. ROAD_CLASS is the English language equivalent of (decodes) the ROARC_COD field. (Source: State of Connecticut, Department of Environmental Protection)
ArcView Legend. Text field for symbolizing road types on a map. (Source: State of Connecticut, Department of Environmental Protection)
| Value | Definition |
|---|---|
| Ferry Crossing | This category includes ROARC_COD value 214. |
| Footbridge | This category includes ROARC_COD value 213. |
| Highway Toll | This category includes ROARC_COD value 403. |
| Local Road | This category includes ROARC_COD values 5, 209, 217, 218, 401209, 610209, and 618209. |
| Non-standard | This category includes ROARC_COD value 405. |
| Parking Area | This category includes ROARC_COD value 215. |
| Primary Route | This category includes ROARC_COD values 201, 202, 203, 204, 401, 402, 401201, 402201, 601202, 618201, and 621201. |
| Rest Area | This category includes ROARC_COD value 613. |
| Secondary Route | This category includes ROARC_COD values 205, 206, 207, 401205, 604203, 610205, and 618205. |
| Trail | This category includes ROARC_COD values 211, 212, and 605211. |
| Under Construction | This category includes ROARC_COD value 604. |
| Unimproved Road | This category includes ROARC_COD values 210, 605210, and 610210. |
Internet Mapping Software Legend. Text field for symbolizing road types on an Internet map. (Source: State of Connecticut, Department of Environmental Protection)
| Value | Definition |
|---|---|
| Major Route | This category includes ROARC_COD values 201, 202, 203, 204, 205, 206, 207, 401, 402, 401201, 401205, 402201, 601202, 604203, 610205, 621201, 618201, and 618205. |
| Local or Unpaved | This category includes ROARC_COD values 5, 209, 210, 217, 218, 405, 401209, 605210, 610209, 610210, and 618209. |
| Trail | This category includes ROARC_COD values 211, 212, and 605211. |
| No Show | This category includes ROARC_COD values 213, 214, 215, 403, 604, and 613. |
Calculated length of feature in miles. Note, LENGTH_MI values are not automatically updated after modifying feature geometry (shape). Values must be recalculated after features are edited, simplified, generalized, clipped, dissolved, etc. (Source: State of Connecticut, Department of Environmental Protection)
Includes linear road and trail features such as highways, routes, local roads, unpaved roads, traffic circles, bridges, cul-de-sacs, and trails published on the U.S. Geological Survey 7.5 minute topographic quadrangle maps. Information encoded about features includes road type classification, two standard symbology classification schemes, and road segment length in miles.
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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Connecticut Roads and Trails is 1:24,000-scale base map data. It depicts the location of all roads and trails 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, Railroads, Airports, and Towns. The Roads and Trails layer includes information within Connecticut and is derived from the Roads and Trails Master layer, which includes all road and trail features depicted on all of the U.S. Geological Survey (USGS) 7.5 minute topographic quadrangle maps that cover the State of Connecticut. This layer may be used as a possible data source for other 1:24,000-scale layers having features that should coincide with the roads and trails on the USGS topographic quadrangle maps. Not intended for maps printed at map scales greater or more detailed than 1:24,000 scale (1 inch = 2,000 feet.)
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 Roads and Trails 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.
In the absence of Large Scale DLG data, the USGS provided the State of Connecticut with raster image scans of the mylar separates used to publish the black, red, brown, and blue inks for 3 of the 115 topographic quadrangle maps that cover Connecticut. These quadrangles include West Springfield Mass-Conn, Springfield South Mass-Conn, and Hamden Mass-Conn.
Road and Trail features for each quadrangle map.
Road and Trail features for Connecticut combined in a single, statewide layer. Road is in ArcInfo Coverage format.
Road and Trail features for Connecticut combined in a single, statewide layer. Road.shp is in Shapefile format.
Road and Trail features for Connecticut combined in a single, statewide layer. Road 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 Road and Trail 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) Railroads, and (3) Pipelines, Transmission Lines, and Miscellaneous Transportation Features. Only the Road and Trails 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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Image to vector (ArcInfo coverage) format conversion - Using ESRI ArcInfo software, the black ink image files that depict the road and trail features on three topographic quadrangle maps were georeferenced to Connecticut State Plane, North American Datum of 1927 (NAD27) by registering the image corners to the corresponding quadrangle corner tics. In an interactive ArcInfo editing environment, the road and trail features were visually identified on the background image and manually vectorized. Road and trail features that would have been included in the DLG Transportation category by the USGS were were manually digitized on the screen (heads-up digitizing). Features were assigned ROARC_COD values based on their cartographic representation on the topographic quadrangle maps. Check plots were made to inspect digitizing quality and the assignment of ROARC_COD values.
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Attribute value verification - The quality and accuracy of the digitizing and coding of the road and trail features was checked by comparing the transporation features in each ArcInfo Coverage with the road and trail 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 ROARC_COD attribute in the final Roads and Trails layer.
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Quadrangle coverage edgematch - Using ESRI ArcInfo software, the individual 7.5 minute quadrangle coverages of Road and Trail 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 Road and trail segments were snapped to align with the connecting stationary features on adjacent quadrangles if their end-points were generally within 20 feet. On occasion, there were no connecting features on adjacent quadrangles to match to so some features abruptly end at quadrangle boundaries. This is mostly due to variations in quadrangle publication dates. Varying publication dates also explain inconsistent DLG major and minor codes for certain roads that appear on more than one topographic map. For example, a road that appears on two adjacent quadrangle maps may appear unpaved on one map and paved on the adjacent (more recent) map. Consequently, ROARC_COD values for some roads change when crossing quadrangle boundaries. These inconsistencies 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 Roads and Trails 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 Roads and Trails 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 Roads and Trails 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 - ROAD_CLASS and AV_LEGEND attributes were changed from storing abbreviated values in upper case (e.g. HWAY PRIM, HWAY SECON, LOCAL ROAD ) to full length values in both upper and lower case (e.g. Primary Route, Secondary Route, Local Road). Additionally the IMS_LEGEND attribute was added to establish a very general classification scheme for symbolizing road and trail features with Internet mapping software environments such as ArcIMS. The following attributes from the original DLG files were removed from the data table due to poor data quality: PHOTRV_FLG, QUAD_NO, OVRPAS_COD, LIMACC_FLG, and NO_LANES. 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 Roads and Trails layer that is clipped to the State of Connecticut boundary.
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Create 2005 Edition of Road - 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 Road 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 ROAD. Note, this particular run of the MAKECOVER.AML created a copy of the Road ArcInfo coverage that is clipped to the State of Connecticut boundary and is named ROAD instead of ROADMASTER. Prior to 2005, the Roads and Trails layer in ArcInfo Coverage format that was clipped to the state of Connecticut boundary was named ROADCT.
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Export to Shapefile format - Converted line feature data from an ArcInfo coverage named ROAD to a Shapefile named Road.shp. Excluded the FNODE#, TNODE#, LPOLY#, RPOLY#, LENGTH, ROAD#, ROAD-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 Road; and imported the attribute definitions, loaded features and imported metadata from Road.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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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 ROARC_COD attribute values was conducted by comparing the roads and trails published on the source topographic quadrangle maps with 1:24,000-scale check plots or interactive displays of the roads and trails data on a computer graphic system. These checkplots and computer displays depicted the road and trail features in different colors based on their respective ROARC_COD values for comparison with the paper quadrangle maps. The ROAD_CLASS, AV_LEGEND, and IMS_LEGEND attribute values are based on ROARC_COD values. ROAD_CLASS decodes the ROARC_COD field. AV_LEGEND and IMS_LEGEND are broad classifications of ROARC_COD values. The ROAD_CLASS, AV_LEGEND, and IMS_LEGEND fields were populated though table joins to lookup tables. These values were not manually entered. The LENGTH_MI (length in miles) field was automatically calculated for each feature base on computer generated feature length in feet.
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.
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 Roads and Trails 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 Roads and Trails layer. So compared to the most recent set of topographic quadrangle maps available today, the Roads and Trails layer is incomplete, and substantially incomplete when compared to the network of highways and streets in existence today. This data is not updated.
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).
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: Roads - From the Roads and Trails layer, compiled and published by CT DEP and USGS. Source map scale is 1:24,000.
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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.
| Data format: | in format Shapefile, Feature Class, ArcInfo Coverage (version ArcGIS) |
|---|---|
| Network links: | http://www.ct.gov/deep |
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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