This is a MetroGIS Regionally Endorsed dataset.
As of the December 1st, 1998 release, the roads file contains street name annotation. Additional related datasets provided with the street centerline data include landmark information such as schools, shopping centers, hospitals, cemeteries, lakes, streams, railroads and various other areas and points of interest. Metadata for the related datasets is provided separately. The centerline dataset is in Arc/Info, double precision format and was developed for use in a variety of GIS applications. Some typical applications that utilize the dataset are automated routing and address matching applications. The delivered output format of the file can be utilized by a variety of software systems. This dataset was not developed from a TIGER base, rather, it is a composite from numerous resources.
A unique identification number is maintained by TLG to allow data files to be related which refer to a unique road segment for use with road maintenance link node modeling and other applications. The unique identification number may be attached to end user data files and distributed without violating the license.
In May of 1997, an agreement for the licensed use of The Lawrence Group (TLG) Street Centerline data was completed by Metropolitan Council, Minnesota Department of Transportation (Mn/DOT) and TLG. The agreement makes TLG Street Centerline data available to all State and Local Government agencies and Colleges and Universities in the State of Minnesota. Mn/DOT and the Metropolitan Council have funded the licensing of the TLG Street Centerline data for use by these organizations to promote standardization and sharing of geographic information.
Note: Other counties are currently under development throughout Minnesota and portions of western Wisconsin.
Features and their attributes are added and updated in TLG's internal dataset on a daily basis. Updating occurs on a city by city basis; therefore, data currency varies. Throughout the course of a year, TLG completes an update of the entire 7 county Twin Cities Metro Area. On a quarterly basis, TLG updates approximately one quarter of all street information - including the addition of street geometry and attribute updates.
Additions and changes submitted to TLG by Minnesota public users will be available in the first quarterly update that occurs 90 days after the changes are submitted.
Under License agreement the data will be made available to Minnesota State Public Agencies, all Minnesota Post-Secondary Education Institutions, and Partners in the 'Orion Project'. For these users, data will be accessed via the Metropolitan Council whereby access to the centerline data is made through an FTP site that users may access once the license agreement has been signed. See Ordering Instructions in Section 6.
While for the Minnesota public users mentioned in 'Access Constraints' there is no charge for the license, there are some responsibilities by which users agree to abide. These include: - Submit roadway and address information additions and changes to TLG so that they may be incorporated into the street centerline dataset and made available in future quarterly updates. - Take measures to prevent the distribution of the TLG data to unauthorized users since it is proprietary trade secret information, making it non-public data. - Determining appropriate applications for the use of the data are the responsibility of the user.
TLG uses extensive address lists as a means for checking address range completeness and currency. Address matches are used to target new areas as well as existing areas in need of update.
Street Naming exists in two manners: 1) As a comprehensive name field that includes all of the street naming components; and 2) as parsed street name components including prefix direction, street name portion, street type, and suffix direction. Street types meet United States Postal Service standards. In instances where the street type is not covered by the USPS, TLG has developed it's own standard. This standard will be easily modified if the USPS releases a different standard in the future for those street types. Currently, TLG uses its best efforts to establish the proper street name for a given segment. We do not use a name which we have sufficient reason to believe is incorrect. Therefore, since no one resource for street names is correct in all cases, TLG uses multiple references in efforts to achieve the correct name.
Municipal and County attributes are encoded based on boundary information provided by cities, counties and the Minnesota Department of Transportation. In order to provide uniformity between the TLG dataset and other digital files available, TLG will begin to use MnDOT as the source for boundary information in late 1997.
Also see Completeness below
TLG maintains private streets as well. The completeness of these streets is unknown. As TLG becomes aware of their existence, they are added to the database.
There are differing degrees of positional accuracy throughout the file. TLG adjusts the positional accuracy of the data to available sources known to have a greater degrees of accuracy then those used to generate the existing data. However, in all cases (including instances where COGO line work has been the reference) TLG generalizes the street segments to at least 4 feet in order to greatly reduce the number of vertices - thus reducing unnecessary file size and allowing for faster analysis.
TLG's goal is to have 95% of roads located to within the approximate center of digital right-of-way data or pavement centerlines provided from counties, where such digital data is available. In other areas, 95% of roads are intended to be within ten meters of the road or right-of-way center.
For the counties of Dakota and Washington, TLG has adjusted the positional alignment of its centerlines by referencing the Washington and Dakota County Surveyors department geospatial dataset. Positional adjustments were also made to data supplied by the Ramsey County Public Works department in May 1998. These adjustments were made relative to each county's centerline dataset. TLG was informed that Ramsey County was continuing to review their own data for positional accuracy; however, TLG's adjustment was necessary in order that users could more efficiently utilize both datasets concurrently. Due to the large number of changes, the Ramsey County adjustments are noted here in the metadata rather than being reflected in the quarterly change report as individual segment changes.
Additionally, positional adjustments were made as of July 31, 1998 to street centerlines within the city of Minneapolis. These changes were made relative to street centerlines provided by the city of Minneapolis. Again, due to the large number of changes, these positional adjustments are noted here rather than in the quarterly change report.
Further positional adjustments were begun in 2002 as TLG began aligning roads to county supplied parcel data and 2000 aerial photography. As of March 1, 2002, Anoka, Carver, Hennepin, Ramsey, and Washington had recieved major updates, effectively modifying the positional accuracy of the entire database. These positional changes have not been individually tracked in the tlgedits.dbf file since they are being changed entirely and the delay to the system would have been too time consuming. Users should make note of this.
For all other areas, various resources were used. For more information please review the section on lineage that follows. Again, as datasets of greater known accuracy become available, TLG's goal is to adjust its centerline database based on those reference sources.
TLG uses several large address datasets as well as municipally provided address files to cross reference against the street centerline data. These have been extremely beneficial for updating and improving address range and street segment information. Feedback from our current users (both public and private sector) has always been important as well.
The provided attribute items have been in place since 1991 and have only changed slightly since that time.
Should the original source be hardcopy, TLG digitizes (via a tablet) new street centerlines. If the data is in a vector or raster format, TLG projects or registers the source to fit the working coordinate system of Minnesota South State Plane (feet). Linear features are then entered by heads-up digitizing means. Should we be referencing accurate centerline files provided to us, we utilize snapping techniques to adjust the positional accuracy.
Attributes are then gathered from numerous sources. Municipalities are the primary source of the address information populating the four address fields. When unavailable, TLG uses known street ranges to populate these fields.
In 1997, TLG incorporated a greatly modified data tracking and reporting procedure for internal use as well as for user assistance in tracking changes to the dataset. See metadata for the ''TLG Street Centerline Edits Table'' for details.
ALT_NAM2: Alternate street name 2 F_XSTREET: From cross street T_XSTREET: To cross street CENST_L: State code (left side) CENCTY_L: County code (left side)
CENMUN_L: Municipal code (left side) CENST_R: State code (right side) CENCTY_R: County code (right side) CENMUN_R: Municipal code (right side) FIPS5_L: 5 Digit FIPS municipal or place code (left side) FIPS5_R: 5 Digit FIPS municipal or place code (right side) ZIP5_L: 5 Digit Zip Code (left side) ZIP5_R: 5 Digit Zip Code (right side) CITYLEFTL: Alpha city name (left side) CITYRIGT: Alpha city name (right side) PREDIR: Prefix street direction STREETNAME: Street name portion of entire street name TYPE: Street type. A list of most of these is available from the USPS web site at <http://pe.usps.gov/text/pub28/pub28apc.html#508hdr2> . SUFDIR: Suffix street direction CTYLABRV: City name abbreviation (left) CTYRABRV: City name abbreviation (right) SPEED_LIM: Generalized speed limits ONEWAY: One way status HIGHWAY_NU: Highway/County road number or letter TLGID: Unique identification number Street centerline attribute notes: a. - The first seven fields represent standard Arc/Info items b. - Street address ranges do not necessarily exist where only theoretical ranges exist; however, in many cases they do. c. - Feature class codes (f_class) are generalized versions of the U.S. census bureau standards. Namely: Typical Interstates are labeled A10, Interstate HOV lanes are labeled A15 (new with Dec. '98 release), US highways A20, State highways A25, County Roads A30, City Streets A40, Ramps and Loops A63, Service Drives A64, Private Roads A66, Dormitory Walkways A71, and Restricted Access A98. As of release 2.2b (a mid-quarter update on August 5, 1998), US highways and State Highways were split into two distinct feature class codes of A20 (US Highways) and A25 (State Highways). d. - Streetall represents the full street name. Predir, Streetname, Type, and Sufdir represent parsed components of streetall as parsed to standard USPS types and USPS standard direction names. e. - F_xstreet and T_xstreet are the values for streetall of the from and to cross streets for each segment based on the from and to nodes. (new item with Dec. '98 release - currently only populated in the 7 county metro area) f. - Due to address matching and parsing issues, street directions are always placed in the suffix direction field. Street names containing direction names as part of their actual street name are originally parsed and then incorporated back into the street item and removed from the predir item. g. - Fips5_l and Fips5_r are unique 5 digit numeric Federal Information Processing Standards (FIPS) cods. h. - Citylabrv and Cityrabrv are unique alpha city name abbreviations as produced by The Lawrence Group. These fields are named in conjunction with Twin Cities metro area street atlas produced by TLG. h. - Speed_lim is a generalized field where speed limits are populated at this time based only on the f_class of a given segment. i. - Oneway is a field which is encoded with a 2 if the street is two-way, a 1 if the segment represents a one-way street on which traffic moves in the direction of the flow of the segment; and -1 if the segment represents a one-way street on which traffic moves in the opposite direction of the flow of the segment. j. - Highway_num is the primary highway or county road number or letter, this number is taken from the name with the highest feature class code on each street segment. (new item with Dec. '98 release) k. - The TLGID (and <cover>-id) are the same value per segment and these identification numbers remain consistent for each release of the database.
See license agreement for complete information.
FOR MINNESOTA PUBLIC USERS (see 'Access Constraints' in Section 1 of the full metadata.): Instructions for licensing the dataset may be found on the MetroGIS web site at <http://www.metrogis.org/data/datasets/street_centerlines/order_info/index.shtml> . You may download copies of the license agreement and instructions via this link. Once you have completed the license and the appropriate person has signed two copies of the agreement, it must be sent to The Lawrence Group (TLG). TLG will sign the two license agreements, return a copy to you and inform the Metropolitan Council that you are a new licensee. Metropolitan Council will then send an account ID and password to you, allowing you to download the data and future updates according to the provisions of the license.
Instructions on how to download the data (once you have your account and password) can be found on the MetroGIS web site at <http://www.metrogis.org/data/datasets/street_centerlines/order_info/download_ftp.shtml> .
FOR OTHER USERS: Contact Jim Maxwell at The Lawrence Group (see 'Contact Person' in Section 1).