Functional roadways classifications identify what function roadways should perform before determining street widths, speed limits, intersection control or other design features. Functional classification ensures that non-transportation factors, such as land use and development, are considered in planning and design of streets and highways.
The classifications also determine which routes should be part of the metropolitan highway system and which should receive regionally-allocated federal funds.
The Federal Highway Administration (FHWA) requires the region to track designations and mileage of the existing highway system for various reasons. Cities, counties and MnDOT may also designate the functional classification of planned highways under their jurisdiction.
4 classes of roadways
The functional roadway classification system within the Twin Cities metro area consists of four classes of roadways:
- principal arterials (which include interstate freeways)
- minor arterials
- collector streets
- local streets
Principal arterials - 5.3%
The Metropolitan Highway System consists of 915 miles of principal arterials which represents 5.3% of road miles in the region. The principal arterials are the most heavily used roads in the area, carrying about 48% of the total vehicle miles traveled in the region. These roads are usually Interstate highways and other freeways or expressways. They are designed to carry longer trips at higher speeds with minimal land access. These roads are primarily owned and operated by MnDOT, although four are under the jurisdiction of counties. Changes to the Principal Arterial network are rigorously reviewed and must be approved by the MPO.
Minor arterials - 14.1%
There are 2,444 miles of minor arterials roads in the seven county metropolitan area, making up 14.1% of system miles. The region has subdivided the minor arterials into A-minors and Other Arterials (formerly called B-minor arterials). The A-minors are intended to supplement the capacity of the Principal Arterials and can compete for regionally allocated federal funds. There are 1942 centerline miles of these roads which are owned by MnDOT, counties, and cities. The A-minor system carries about 26% of the total vehicles miles traveled in the region.
Collectors and local roads - 80%
There are approximately 14,000 miles of collectors and local streets in the region; their primary function is land access. Local units of governments are responsible for planning for collectors and local roads.
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