Single Point Urban Interchange (SPUI)

The SPUI is a type of interchange where the arterial and ramp entrances/exits are controlled by a single traffic signal. This type of interchange can be more efficient than a standard diamond interchange and takes up less space. A variation of the SPUI that has been used extensively in other countries is to replace the signal with a single roundabout.

References

MD Arterial Intersection Design
Applied Technology and Traffic Analysis Program

SPUI Overview
Pronounced "Spooey", the Single-Point Urban Interchange is a relatively new variant of the diamond. The SPUI's advantages (for appropriate situations) include: compact layout; requires less right-of-way acquisition; allows concurrent left turns for greater capacity.
SPUI Overview

SPUI Video
Interchanges in heavily developed urban areas must move an ever-increasing volume of traffic through limited amounts of space. One way to maximize the flow of traffic in urban areas is through use of Single Point Urban Interchanges. The Single Point, also known as an X-interchange or Urban Diamond, is being used extensively in urban highway construction and reconstruction across the country.
SPUI Video