Metro Freeway Congestion Report
About the measures
MnDOT defines freeway congestion as traffic flowing at speeds less than or equal to 45 miles per hour (mph). This definition does not include delays that may occur at speeds greater than 45 mph.
The 45-mph speed limit was selected because it is the speed where “shock waves” can spread. These conditions also increase the risk of crashes. Although shock waves can occur above 45 mph there is a distinct difference in traffic flow above and below the 45-mph limit.
A shock wave is a phenomenon where most of the vehicles brake in a traffic stream. Situations that can create shock waves include:
- Changes in the characteristics of the roadway, such as a lane ending, a change in grade or curvature, narrowing of shoulders, or an entrance ramp where large traffic volumes enter the freeway.
- Large volumes of traffic at major interchanges with high weaving volumes and entrance ramps causing the demand on the freeway to reach or exceed design capacity.
- Traffic incidents, such as crashes, stalled vehicles, animals or debris on the roadway, adverse weather conditions, and special events.
Driver habits can also contribute to shock waves. Driver inattentiveness can result in minor speed variations in dense traffic or sudden braking in more general conditions.
Electronic surveillance systems exist on about 95% of the metro area freeway system. To report congestion, MnDOT’s Regional Transportation Management Center (RTMC) collected October 2023 data from 4,000 traffic sensors on Twin Cities Metro freeways which are either loop detectors embedded in the pavement or radar sensors mounted on the roadside. On corridors without electronic surveillance systems, the RTMC began using probe data provided by HERE which gives average vehicle speeds along a corridor over a given time.
The RTMC evaluates the 782 directional miles of the Twin Cities urban freeway system to develop the AM plus Hwy PM percentage of Directional Metro Freeway Miles Congested. It tracks the percentage of miles that operate at speeds below 45 mph for any length of time during the morning and afternoon peak periods (782 miles morning and 782 miles afternoon).
Mainline detectors are in each lane of a freeway at approximately one-half mile intervals.
Speed data is based on the median value of data collected at detector locations. Median values are calculated for each five-minute interval for the periods of 5-10 a.m. and 2-7 p.m. for the twelve midweek days in October. MnDOT uses medians, rather than averages, to minimize the effects of extremes in the data. This process mitigates those occasions of roadwork, lane closures, significant traffic incidents, and one-time traffic events not related to daily commuting patterns.
- 2023 AM Metro Freeway Congestion Map (PDF)
- 2023 PM Metro Freeway Congestion Map (PDF)
- 2023 All Day Metro Congestion Map (PDF)
Recent trends
Freeway congestion steadily increased since 2020 to nearly pre-COVID-19 trends. In 2023, the annual freeway congestion was 22.1%. The COVID-19 pandemic had a major impact on congestion levels in 2020, as commuting patterns drastically changed because of stay-at-home orders and then a significant number of people working remotely. During both morning and afternoon peak hours, Interstate 94 had the most congestion. In terms of daily traffic volume, the total vehicle miles traveled has increased closer to pre-pandemic levels compared to most recent years.
Where we want to go
Increasing traffic congestion increases fuel usage and emissions, creates a higher risk for crashes, increases shipping costs, and reduces the time available to spend on other activities. Factors that affect congestion include economic conditions and population growth. To ensure reasonable travel time for commuters and travelers and reduce congestion on the interstate highway system, MnDOT currently relies on several strategies including active traffic management (e.g., an advanced system of cameras, loop detectors, and ramp meters), low-cost spot mobility improvements to improve traffic flow, E-Z Pass lanes, and strategic capacity enhancements (e.g., bus-only shoulders and interchange capacity improvements). MnDOT also maintains and updates a Statewide Freight System and Investment Plan, a State Rail Plan, and a Statewide Ports and Waterways Plan to advance freight, railway, waterway, and multimodal planning and integration.