MnDOT BaseMap History
Although posting the GIS BaseMap information to the Internet is new for
MnDOT the BaseMap has had a long history in MnDOT. In 1979, MnDOT began
using a computer aided drafting (CAD) workstation to begin the process
of converting hand drafted MnDOT cartography into electronic files for
computer plotting. Work began on digitizing Minnesota's 1,745 USGS 1:24,000
scale quadrangles to obtain seamless digital map coverage for all of Minnesota.
By 1985, the seven-county St. Paul-Minneapolis Metropolitan Area was completed
and a set of 50 edge matched CAD files containing all public road centerlines,
railroads, political/administrative boundaries, the Public Land Survey
System and surface water was produced. In the following year, the first
MnDOT County Highway Map was produced. To date, MnDOT produces and annually
updates all of its CAD county maps, all maps for cities having a population
$ 5,000, a 7+ county Metro Area Street Series, the Minnesota Official
Highway Map and approximately 40% of the map sheets for cities having
a population of less than 5,000.
In the late 1980's, MnDOT began to research the potential offered by
the exploding use of Geographic Information System (GIS) technology for
its own needs and services. A series of internal task forces and consultation
with the state Land Management Information Center (LMIC) resulted in a
1992 decision to incorporate the CAD digitizing completed to date into
a statewide seamless basic core of geography that would provide a means
for relating MnDOT spatial data to other spatial data. The GIS software
chosen was Environmental System Research Institute's (ESRI) Arc/Info.
Digitizing would continue but at an accelerated pace to complete statewide
1:24,000 scale coverage within 18 months. MnDOT also switched from using
State Plane Coordinates zone specific, NAD83 to Universal Transverse Mercator
(UTM) Minnesota extended Zone 15, NAD83 coordinates.
In March of 1993, the MnDOT Cartographic Unit began converting and updating
the 35% of statewide quad coverage already completed and accelerating
the digitizing of the state's remaining quad coverage. By the end of 1994,
digitizing was completed and work began on creating Arc/Info GIS coverages
from the CAD digitizing. In 1996, MnDOT produced its first State of Minnesota
GIS BaseMap on a CD-ROM. While the BaseMap did not contain attribution
for all its 21 data layers, it did fulfill MnDOT's initial goal of providing
a data set on which to display other MnDOT spatial information.
MnDOT provides annual updates to the BaseMap. The Minnesota Trunk Highway
(TH) and County State Aid System (CSAH) alignment and route coverages
as well as the municipal boundary coverage were updated. Also accomplished
was additional attribution for Municipal State Aid Streets (MSAS), County
Roads (CR), railroads, and civil townships and selected state/federal
agency administrative boundaries (forests, parks, etc.). In preparation
for BaseMap 2000, a concerted effort began to capture the alignment of
all local city streets built since the release of the original BaseMap
1996.
The Enhanced BaseMap
Now available on the Internet is the enhanced BaseMap. Recently completed,
this was a two-year project to update the entire public transportation
system. This included adding new roads for all systems, providing additional
and updated attribute information, creating metadata for individual data
sets, and building routes for the entire system.
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