Innovative Intersections and Interchanges

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Innovative Intersection: Thru-cut
Park and Locust Streets in Vienna, Va.
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What Is A Thru-cut?

  • Intersection design where side street through movements are prohibited
  • Side street motorists turn left or right and make another turn at an existing opening to cross the major street
  • Side street left and right turn lanes may be channelized using physical barriers or pavement markings
  • Main intersection may be controlled with a traffic signal, stop signs or yield signs

When Should It Be Considered?

  • On median-divided highways
  • At intersections with low side street through traffic volumes
  • At intersections with heavy major street through and/or left-turn traffic volumes
  • At intersections where side street through movements can be accommodated by rerouting to existing intersections or median openings
  • At intersections with four legs

Benefits

  • Improved safety: Reduces the number of points where vehicles cross paths
  • Increased efficiency: Eliminates the side street through movements, allowing for fewer or shorter traffic signal phases, which reduces delay and increases capacity
  • Shorter wait times: Fewer traffic signal phases means less time stopped at the intersection
  • Cost effective: A thru-cut may be more cost-effective than adding lanes to improve capacity

How to Navigate

Below shows how to navigate a thru-cut intersection. Click the image to view a larger version or watch the video (coming soon).

Thru-cut navigation diagram

Conflict Points

The number of conflict points (where travel paths intersect) 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 movements and associated conflict points at a conventional four-leg intersection to a thru-cut.

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

When compared to a conventional four-leg intersection, a thru-cut has 8 fewer crossing, 2 fewer merging, and 2 fewer diverging conflict points.

Conventional Intersection: Conflict Points

Conventional Intersection conflict diagram.

Legend

Diagram Legend. Filled circle is diverging, half-filled is merging, empty is crossing.
Conflict Type Count
Crossing 16
Merging 8
Diverging 8
Total:

32 Conflicts

Thru-cut: Conflict Points

Thru-cut conflict diagram.

Legend

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

20 Conflicts

Resources

Virginia Department of Transportation

Page last modified: Nov. 17, 2020