Innovative Intersections and Interchanges
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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
- 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.
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
Thru-cut: Conflict Points