Innovative Intersections and Interchanges

 

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Michigan Urban Diamond (MUD) icon
Innovative Intersection: Michigan Urban Diamond (MUD)
I-696 at Coolidge Highway, Oak Park, Mich.

An MUD is also known as:

  • Median U-turn (MUT) Interchange

What Is A MUD?

  • A grade-separated interchange where left-turning motorists make a U-turn at an adjacent crossover to complete the desired movement
  • The crossovers are parallel to the arterial and are accessed from one-way frontage roads adjacent to the freeway
  • No left turns are permitted at the main intersection
  • Can be signalized, stop controlled, or yield controlled

When Should It Be Considered?

  • With moderate to heavy through traffic volumes and low to moderate left-turn traffic volumes
  • With existing frontage roads
  • Where access to properties and businesses adjacent to the freeway is important

Benefits

  • Improved safety: Reduces the number of points where vehicles cross paths and decreases the potential for angle crashes
  • Increased efficiency: Eliminates left-turn movements from the main intersection, allowing fewer traffic signal phases, which reduces delay and increases capacity
  • Better synchronization: Fewer traffic signal phases means less time stopped at the main intersection

How to Navigate

Below shows how to navigate a MUD interchange. Click the image to view a larger version .

MUD navigation diagram

Conflict Points

The number of conflict points (locations where vehicle travel paths intersect) is one metric that can be used to evaluate the safety of an innovative intersection or interchange.

There are three categories: crossing, merging or diverging.

In general, merging and diverging conflict points — where vehicles are moving in the same direction — are associated with less severe crash types than crossing conflict points where vehicles are moving in opposite directions.

The diagrams below compare possible vehicle travel movements and associated conflict points at a conventional diamond interchange to an MUD.

These diagrams represent a general case, with one travel lane in each direction, and do not take into account pedestrian or bicycle movements at an intersection or interchange.

When compared to a conventional diamond interchange, an MUD has two fewer crossing conflict points.

Conventional Diamond Interchange: Conflict Points

Conventional Intersection conflict diagram.

Legend

Diagram Legend. Filled circle is diverging, half-filled is merging, empty is crossing.
Conflict Type Count
Crossing 6
Merging 8
Diverging 8
Total:

22 Conflicts

MUD: Conflict Points

MUD conflict diagram.

Legend

Diagram Legend. Filled circle is diverging, half-filled is merging, empty is crossing.
Conflict Type Count
Crossing 4
Merging 8
Diverging 8
Total:

20 Conflicts

Resources

Virginia Department of Transportation

Federal Highway Administration

Page last modified: Nov. 7, 2019