Innovative Intersections and Interchanges

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.

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 Legend Conflict Type Count Crossing 16 Merging 8 Diverging 8 Total: 32 Conflicts

Thru-cut: Conflict Points Legend Conflict Type Count Crossing 8  Merging 6  Diverging 6  Total: 20 Conflicts

Resources