Definitions of Common Acronyms

The following lists definitions of common terms and acronym used on my highway and road photo pages and in my posts on the misc.transport.road newsgroup and various transportation-related mailing lists and forums.

MnDOT - The standard abbreviation I use for the Minnesota Department of Transportation.  The StarTribune and several other newspapers across the state generally use this form of abbreviation as well.  MnDOT itself generally uses Mn/DOT (with a forward slash).

MHD - Acronym for the Minnesota Highway Department.  MHD merged with other transportation-related state agencies to become MnDOT in 1976.

FHWA  - Standard acronym for the Federal Highway Administration.

BPR - Bureau of Public Roads, the precursor to the Federal Highway Administration.

MTC - Short for the Metropolitan Transit Commission, the precursor to today's Metro Transit.

Metro  - The "Metro" is a shortened term commonly used by Minnesotans that refers to the Minneapolis/St. Paul (or "Twin Cities") metropolitan area.  Generally consisting of the counties of Anoka, Carver, Dakota, Hennepin, Ramsey, Scott, and Washington.  The U.S. Census Bureau also includes Wright, Sherburne, Isanti, and Chisago Counties in Minnesota and Pierce and St. Croix Counties in Wisconsin as part of the Twin Cities metro area.

Outstate  -  The other part of Minnesota besides the "Metro".  "Outstate" is what Minnesotans call the rest of Minnesota outside of the Twin Cities metro area.

MnDOT Districts and "Metro Division"  -  Part of MnDOT's organization.  MnDOT is split into 8 districts, each representing a geographical area within the state.  The "Outstate" districts are numbered from 1 to 8 (5 is not used).  "Metro Division" is a specialized district, representing the original 7-county Twin Cities metro area plus Chisago County.  It was formed in the late 1980s by merging the old Districts 5 (west metro) and 9 (east metro) into one entity.  Recently, MnDOT changed its name and simply calls it "Metro District" (to reflect that it is an organizational district like the Outstate districts are).

I-xx -  Interstate highway xx (xx being the route number)
US xx -  United States highway xx (xx being the route number)
MN xx -  Minnesota state highway xx (xx being the route number)

CSAH - County State Aid Highway.  A specialized form of county route that is part of the state aid system.  County State Aid routes are eligible for funding from the County State Aid Highway Fund, which Constitutionally receives funding from just over 1/4 of the proceeds from the state's gas tax, vehicle registration fees, and part of the motor vehicle sales tax.

MSAS - Municipal State Aid System.  Similar to the County State Aid system, this is a system of designated municipal streets in those cities above 5,000 in population, that are not already on the state highway or CSAH systems.  Municipal streets on the MSAS are eligible for funding from the Municipal State Aid Highway Fund, which Constitutionally receives just under 9% of the state funds Constitutionally dedicated to the state's highway fund.

IRC - MnDOT's Interregional Corridor system.  A system of the most important regional and interregional highways in the state, comprising of corridors connecting regional centers to each other and the Twin Cities metropolitan area outside of the I-494/I-694 Beltway.  System highways are designated into three categories:  High-Priority Interregional Corridor, Medium-Priority Interregional Corridor, or Regional Corridor.  By default, all Interstate highways outside of the I-494/I-694 Beltway are High-Priority IRC corridors.

NHS -  National Highway System.  Approved by Congress in 1995, the NHS is a system (designated by FHWA and the various state DOTs) of major roads of national importance or significance.  By default, the Interstate and STRAHNET (routes of importance to defense policy...designated by the Transportation Engineering Agency of the U.S. Army) systems are part of NHS.  Major interregional corridors and roads providing access to multimodal facilities (such as ports, airports, or rail terminals) are also part of the NHS.

AADT - Average Annual Daily Traffic

HCADT - Heavy Commercial Average Daily Traffic

Preservation Corridor - One of four long-range investment strategies designated by MnDOT for a given highway corridor.  "Preservation" corridors will see investments concentrated on preserving the condition of the highway.  Minor improvements may also be considered but moderate improvements and/or capacity expansion are not considered.

Reconstruction Corridor - Fundamentally similar to the "preservation" corridor.  What sets the "reconstruction" corridor apart is the need for significant pavement and/or bridge reconstruction in order to bring the condition of the roadway up to current standards.  Does not include overall capacity expansion.

Management Corridor - "Management" corridors include provisions for preservation of the corridor, but exhibit enough safety or operational performance problems to where moderate improvements to improve safety or mobility are needed.  Common improvements include the various forms of "access management" improvements.  Minor capacity improvements may be considered, but major capacity expansion is generally not considered due to financial constraints or lack of need.  Corridors that have considerable safety and/or mobility issues, as well as corridors that have a major capacity need but lack the funding for capacity expansion, are commonly designated as "management" corridors.

Expansion Corridor - The last of the four long-range investment strategies, "expansion" corridors are those corridors where significant capacity expansion is planned.

Turnback - Not an "investment strategy" per se, though sometimes applied as one.  MnDOT's districts will sometimes identify a given state highway route as a "turnback candidate", which means the route is a candidate for decommissioning with control of the route reverted to the city and/or county in question.  Some recent examples of highways that were "turned back" in the Twin Cities metro are MN 288 in Anoka (which served the Anoka Treatment Center), MN 101 through most of Hennepin County, and parts of MN 120 and MN 244 in the eastern metro.

Access Management - "Access management", as defined by MnDOT, is the planning, design, and implementation of land use and transportation strategies that manage the flow of traffic between the road and surrounding land.  It consists of various low- and mid-cost improvements to improve and/or channelize traffic flow along a highway.  Adequate spacing and appropriate design of intersections, along with construction of frontage roads or consolidated driveways for private access, are examples of access management.  MnDOT has a full resource page on the topic.

Super-2  -  MnDOT's definition of a "Super-2" is basically equivalent to that of a 2-lane expressway.  Wide shoulders, turn lanes (including left turn lanes), passing lanes in selected locations, current geometric standards, and high design speed.  A "Super-2" may or may not have partial control of access.  My term for this is an "Improved-2", as I consider a "Super-2 expressway" to have partial- or limited-access (i.e. no private access points).

SPUI  -  Stands for Single-Point Urban Interchange.  A modified form of a diamond interchange where all four ramps come together at a single intersection instead of at two separate intersections.  Traffic operations are improved both due to having only a single traffic signal as well as requiring only a 3-phase timing for that signal.  SPUIs are more efficient than a standard diamond and can fit into a tight ROW, but the extra bridging and retaining walls required drives their cost up considerably.

HOV-x - Stands for High Occupancy Vehicle.  Usually applies to a special freeway lane which is reserved for use by buses, motorcycles, and passenger vehicles carrying the required number of passengers.  The "x" in the acronym defines the minimum number of vehicle occupants needed to satisfy the HOV requirement.  Most HOV lanes across the U.S. are HOV-2, meaning at least two people in the vehicle (one of which is the driver, of course) are needed to satisfy the HOV requirement.

HO/T - Stands for High Occupancy/Toll.  This is a specialized form of HOV lane where single-occupancy vehicles or vehicles not meeting the minimum occupancy requirements for HOV can pay a toll to use the lane.    The lanes are still free for valid HOV vehicles.  They are often called "Lexus Lanes" by critics.  Within Minnesota, the I-394 express/toll lanes are considered to be HO/T lanes.

EIS - Short for Environmental Impact Statement.  A project document that looks at all reasonable and feasible alternatives, and the social and environmental impacts of those alternatives, as part of the process for selecting an alternative and design for a given project.  Is generally split into a Draft EIS and a Final EIS.  The Draft EIS documents all the alternatives for a given project, while the Final EIS provides further documentation and study of the "preferred alternative".

NAIP - National Agriculture Imagery Program.  A program of the U.S. Department of Agriculture that develops and makes available aerial imagery of much of the U.S. on a regular basis, often annually.  This imagery is made available in MrSID (short for multiresolution seamless image database) format.  MrSID data can be viewed via a plug-in (LizardTech makes a free plug-in), or can be imported into a GIS platform such as ArcGIS for further analysis.  I have used NAIP imagery to create several maps on my pages, and have also used it to show aerial views of several route termini and Twin Cities area interchanges.


Last updated 15 June, 2008