Illinois Roads from USGS 1:100,000-scale Digital Line Graphs (1980-1986)

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Frequently-anticipated questions:


What does this data set describe?

Title:
Illinois Roads from USGS 1:100,000-scale Digital Line Graphs (1980-1986)
Abstract:
This ArcSDE feature dataset contains roads in Illinois as derived from US Geological Survey 1:100,000-scale Digital Line Graph files, transportation layer, 1980-1986. This includes all the DLG roads data that ISGS/IDNR customarily stored by county-by-county prior to 2004. The dataset is subdivided into four feature classes: interstates and defense highways, U.S. highways, Illinois state routes, and "all roads", which includes the three previous classes plus most local roads as of 1986. Note that the functional classification of roadways is the jurisdiction of the Illinois Department of Transportation and is subject to change.

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.

Supplemental_Information:
This is edition 20040226 of this feature dataset. While the component feature classes have been available and used as separate components for many years, managing the data as an ArcSDE feature dataset is new as of 2 February 2004. This merits an updated designation. The edition designation is derived from the aforementioned date using FGDC metadata notation.
  1. How should this data set be cited?

    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.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -91.510288
    East_Bounding_Coordinate: -87.500008
    North_Bounding_Coordinate: 42.500065
    South_Bounding_Coordinate: 37.000008

  3. What does it look like?

  4. Does the data set describe conditions during a particular time period?

    Calendar_Date: 1986
    Currentness_Reference: publication date of most recent source for majority of features

  5. What is the general form of this data set?

    Geospatial_Data_Presentation_Form: vector digital data

  6. How does the data set represent geographic features?

    1. How are geographic features stored in the data set?

      This is a Vector data set. It contains the following vector data types (SDTS terminology):

      • String (1198)
      • String (290)
      • String (622577)
      • String (381)

    2. What coordinate system is used to represent geographic features?

      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.

      Vertical_Coordinate_System_Definition:
      Altitude_System_Definition:

  7. How does the data set describe geographic features?

    GISDB.IL_INFRA_ROADS_State_Routes_Ln

    GISDB.IL_INFRA_ROADS_US_Highways_Ln

    GISDB.IL_INFRA_ROADS_All_Roads_Ln

    GISDB.IL_INFRA_ROADS_Interstate_Ln

    Entity_and_Attribute_Overview: Feature class specifics are in the respective metadata.


Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)

  2. Who also contributed to the data set?

    GIS Processing: INHS Staff and ISGS staff Lastest Feature Updates: ISGS staff Documentation: INHS Staff and ISGS staff Quality Control: INHS Staff

  3. To whom should users address questions about the data?

    Contact_Instructions: Please refer to the Distribution Information section.


Why was the data set created?

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.


How was the data set created?

  1. From what previous works were the data drawn?

    none (source 1 of 1)
    Survey, US Geological , 1980-1986, US Geological Survey 1:100,000-scale Digital Line Graph files, transportation layer.

    Type_of_Source_Media: digital file
    Source_Scale_Denominator: 100000
    Source_Contribution:
    Location and description of Illinois roads as contained in the USGS 1:100,000 DLG files

  2. How were the data generated, processed, and modified?

    Date: 1980 (process 1 of 3)
    Derived from the US Geological Survey 1:100,000-scale Digital Line Graph files, transportation layer, 1980-1986. Publication dates of the USGS maps used as sources range from 1980 to 1986.

    Date: 1993 (process 2 of 3)
    Major highways were updated as of 1993 by the Illinois Natural History Survey.

    Date: 26-Feb-2004 (process 3 of 3)
    The source coverage data for the feature classes were reprojected from the customary ISGS Lambert projection, NAD27 to geographic coordinates, NAD83, double-precision. The coverages were imported into the ISGS SDE enterprise database, following steps outlined in ISGS procedure GISDB_0009, and grouped into this feature dataset. Feature-class-specific details are included in the respective metadata.

    This "parent" metadata document was created by amalgamating the coverage metadata.

    Person who carried out this activity:

  3. What similar or related data should the user be aware of?

    , ISGS Terms of Use.

    Online Links:

    , University of Illinois Web Privacy Notice.

    Online Links:

    , University Copyright Policy (stated in the General Rules Concerning University Organization and Procedure, Article III, Section 4).

    Online Links:

    , Policy on Appropriate Use of Computers and Network Systems at the University of Illinois at Urbana-Champaign.

    Online Links:


How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?

    The route number attributes have been widely used since 1986 can be be considered generally accurate. Otherwise, no report.

  2. How accurate are the geographic locations?

    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.

  3. How accurate are the heights or depths?

  4. Where are the gaps in the data? What is missing?

    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>.

  5. How consistent are the relationships among the observations, including topology?

    No logical consistency review has been performed in recent memory. Otherwise, no report.


How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?

Access_Constraints:
ISGS information must be obtained directly from the ISGS or from an authorized distributor. Be aware that ISGS information obtained from an unauthorized third party may have been altered subsequent to original distribution, or may no longer be current.

Any access to these data, Web sites, computer systems, electronic services, and electronic networks is governed by University and campus policies, in particular, but not limited to, the Policy on Appropriate Use of Computers and Network Systems at the University of Illinois at Urbana-Champaign, the ISGS Terms of Use document available at the ISGS Web site, and the University of Illinois Web Privacy Notice.

Links to these are provided in the Cross References section.

Use_Constraints:
ISGS information is the property of and copyrighted by the Board of Trustees of the University of Illinois with all rights reserved.  University copyright policy is stated in the General Rules Concerning University Organization and Procedure, Article III, Section 4. A link is provided in the Cross References section.

Individuals or entities may make fair use of copyrighted ISGS material, such as reproducing a single figure or table, or using a brief text quotation, without obtaining formal permission, but in all cases the Illinois State Geological Survey must be credited as the source of the material. To reproduce ISGS information beyond the fair use standard, permission must be obtained from the ISGS Information Office, 615 East Peabody Drive, Champaign, Illinois 61820, 217-333-4747, isgs@isgs.illinois.edu. License fees and a license agreement may be required, depending on the proposed usage.

Any use of these data is governed by University and campus policies, in particular, but not limited to, the Policy on Appropriate Use of Computers and Network Systems at the University of Illinois at Urbana-Champaign, the ISGS Terms of Use document available at the ISGS Web site, and the University of Illinois Web Privacy Notice. Links to these are provided in the Cross References section.

Map information is to be used at a scientifically and cartographically appropriate scale, that is, at a scale no greater than indicated on the map or as described in the documentation of the map or map data.  Map information is not appropriate for, and is not to be used as, a geodetic, legal, or engineering base. Map information has no legal basis in the definition of boundaries or property lines and is not intended as a substitute for surveyed locations such as can be determined by a registered Public Land Surveyor.

The data do not replace the need for detailed site-specific studies.

  1. Who distributes the data set? (Distributor 1 of 1)

    Information Office, Illinois State Geological Survey (ISGS), a division of the Institute of Natural Resource Sustainability (INRS) of the University of Illinois
    615 East Peabody Drive
    Champaign, Illinois 61820
    USA

    217-333-4747 (voice)
    isgs@isgs.illinois.edu

    Hours_of_Service: 8:00 a.m. - 4:30 p.m., Monday-Friday, U.S. Central Time
  2. What's the catalog number I need to order this data set?

  3. What legal disclaimers am I supposed to read?

    Refer to the Legal Notices of Terms and Conditions of the University of Illinois Web Privacy Policy (there is a link in the Cross References section) for policy statements regarding the following:

    Disclaimer of Liability Disclaimer of Warranties and Accuracy of Data Disclaimer of Endorsement Disclaimer for External Links Disclaimer of Duty to Continue Provision of Data Security Choice of Law

    By obtaining these data you agree to the provisions of the University of Illinois Web Privacy Policy, regardless of the manner in which the information was obtained.

  4. How can I download or order the data?

  5. What hardware or software do I need in order to use the data set?

    The data are intended for use with GIS software. The ISGS uses ESRI ArcGIS software, however, ESRI formats can be imported into many different GIS software packages. It is expected that customers who obtain these data have the technical expertise to use GIS software. The ISGS does not provide software support of any kind.


Who wrote the metadata?

Dates:
Last modified: 24-Feb-2009
Metadata author:

Contact_Instructions: Please refer to the Distribution Information section.
Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)
Metadata extensions used:


Illinois Natural Resources Geospatial Data Clearinghouse

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