For more current road information, including downloadable GIS data, refer to the Illinois Department of Transportation Technology Transfer Center (IDOT T2 Center) at <http://dot.state.il.us/blr/t2center1.html>.
This metadata document describes the SDE feature dataset as a whole and contains information that applies to all the feature classes. Each feature class has an additional unique metadata file describing its specifics.
Publication dates of the USGS maps used as sources range from 1980 to 1986. Major highways were updated as of 1993. The maximum estimated error in horizontal position based on National Map Accuracy Standards is 167 feet. Experience shows that actual locational error appears to be greater, especially in localized areas. Rough comparison of these data with other easily obtainable, low-cost roads data shows that locational accuracy varies from locale to locale. Other datasets have better accuracy in some areas and worse in others. Overall, the general quality of most low-cost roads data appears to be the same, with local variation.
Attributes include road class, road type, DLG code, route numbers, and data source, among others. The All_Roads feature class is the parent of the other three feature classes and contains all attribute information. The Interstate, State_Routes, and US_Highways feature classes are subsets of All_Roads and contain only route numbers.
The data are stored in geographic coordinates, NAD83.
These data have not been updated since 1993, nor are there current plans to do so. With the exception of major highways, the data have not been updated since 1986. Accordingly, these data are for general reference and cartographic use. This is a legacy dataset made available as a convenience. The data are not suitable for showing all local roads at a large scale for any given area. These data can be considered to be essentially out of date and unmaintained.
These data and most of the accompanying metadata were originally developed and maintained by staff of the Illinois Natural History Survey (INHS), an agency of the Illinois Department of Natural Resources (IDNR), under the auspices of the Illinois Geographic Information System (IGIS) initiative (circa 1986). Maintenance of the metadata was transferred to ISGS circa 1996.
Illinois Department of Natural Resources, Illinois Natural History Survey, and Illinois State Geological Survey, 20040226, Illinois Roads from USGS 1:100,000-scale Digital Line Graphs (1980-1986): ISGS GIS Database GISDB.IL_Roads_From_100K_DLG, Illinois State Geological Survey, Champaign, Illinois.
This is a Vector data set. It contains the following vector data types (SDTS terminology):
Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.000001. Longitudes are given to the nearest 0.000001. Latitude and longitude values are specified in Decimal degrees.
The horizontal datum used is North American Datum of 1983.
The ellipsoid used is Geodetic Reference System 80.
The semi-major axis of the ellipsoid used is 6378137.000000.
The flattening of the ellipsoid used is 1/298.257222.
GIS Processing: INHS Staff and ISGS staff Lastest Feature Updates: ISGS staff Documentation: INHS Staff and ISGS staff Quality Control: INHS Staff
217-333-4747 (voice)
isgs@isgs.uiuc.edu
In a natural resources context, these roads data are primarily used as a cartographic element on maps for spatial reference. They are also used for analyses that require, for example, a buffer area between roads and natural features. These data are appropriate for regional thematic analysis. They are not appropriate for local analysis or as a geodetic or engineering base.This dataset serves as an important base cartographic element for many types of maps and has been widely distributed and used outside the ISGS. The data set was not and is not intended as a substitute for surveyed locations, such as can be determined by a registered Public Land Surveyor. Although useful in a GIS as a reference base layer for maps, the data set has no legal basis in the definition of boundaries or property lines.
Survey, US Geological , 1980-1986, US Geological Survey 1:100,000-scale Digital Line Graph files, transportation layer.
This "parent" metadata document was created by amalgamating the coverage metadata.
Person who carried out this activity:
The route number attributes have been widely used since 1986 can be be considered generally accurate. Otherwise, no report.
The maximum estimated error in horizontal position based on National Map Accuracy Standards is 167 feet. Experience shows that actual locational error appears to be greater, especially in localized areas. Rough comparison of these data with other easily obtainable, low-cost roads data shows that locational accuracy varies from locale to locale. Other datasets have better accuracy in some areas and worse in others. Overall, the general quality of most low-cost roads data appears to be the same, with local variation. No accuracy statement was provided with the source data.
Dataset is incomplete. No local roads have been added or updated since 1986. Some highways were updated in 1993. No statement of completeness was provided with the original USGS DLG data. All Illinois roads contained in the source USGS 1:100,000 DLG files are included.
For more current road information, including downloadable GIS data, refer to the Illinois Department of Transportation Technology Transfer Center (IDOT T2 Center) at <http://dot.state.il.us/blr/t2center1.html>.
No logical consistency review has been performed in recent memory. Otherwise, no report.
Are there legal restrictions on access or use of the data?
- Access_Constraints: none
- Use_Constraints:
- Reproduction or redistribution of copyrighted digital data sets or products derived therefrom outside of licensee's organization or entity is expressly forbidden. The only exception is redistribution to consultants working for the licensee, and then only for purposes, related to work for the licensee. Such consultants may not further reproduce or redistribute these data sets. None of these data shall be electronically duplicated on magnetic or optical media for use by others, in whole or in part, without permission of DNR.
Any hardcopies utilizing DNR data sets shall clearly indicate their source. If the licensee has modified the data in any way they are obligated to describe the types of modifications they have performed on the hardcopy map. Licensee specifically agrees not to misrepresent DNR data sets, nor to imply that changes they made were approved by DNR.
The Illinois Department of Natural Resources (DNR) provides these geographic data "as is." DNR makes no guarantee or warranty concerning the accuracy of information contained in the geographic data. DNR further makes no warranties, either expressed or implied as to any other matter whatsoever, including, without limitation, the condition of the product, or its fitness for any particular purpose. The burden for determining fitness for use lies entirely with the user. Although these data have been processed successfully on computers of DNR, no warranty, expressed or implied, is made by DNR regarding the use of these data on any other system, nor does the fact of distribution constitute or imply any such warranty.In no event shall the DNR have any liability whatsoever for payment of any consequential, incidental, indirect, special, or tort damages of any kind, including, but not limited to, any loss of profits arising out of use of or reliance on the geographic data or arising out of the delivery, installation, operation, or support by DNR.
The data are intended for use with GIS software. The ISGS uses ESRI ArcGIS software, however, the ESRI shapefile format can be imported into many different GIS software packages. It is expected that customers who order this data have the technical expertise to use GIS software. The ISGS does not provide software support of any kind.