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Single Point Urban Interchange Frequently Asked Questions

  1. How do Single Point Urban Interchanges compare with more traditional interchange types?
  2. How do Single Point Urban Interchanges decrease congestion?
  3. What about pedestrians and bicycles?
  4. Why are Single Point Urban Interchanges more efficient?
  5. How well do Single Point Urban Interchanges work on I-64?

How do Single Point Urban Interchanges compare with more traditional interchange types?

The Single Point certainly looks and feels different, because there is so much open space in the middle of the interchange.

A nationwide survey conducted in 1997 compared the safety of Single Points with Diamond Interchanges. The survey determined that was no significant difference between the two in overall safety, and called the Single Point "a safe, efficient design that can decrease delay and congestion."

 

How do Single Point Urban Interchanges decrease congestion?

Let's compare two designs:

Diamond Interchange 1 Diamond Interchange 2 Single Point Urban Interchange
Diamond Interchange Diamond Interchange Single Point Urban Interchange
Click here to see the full-sized photo sequence.
(Click Page Up or Page Down to move between photos. Link opens in new window)
  • In the Diamond interchange, the streams of left-turning traffic cross each other. Traffic signals on either end can keep turning vehicles from clearing the interchange. It may take several traffic signal cycles for a vehicle to make a turn and then leave the interchange.
  • In the Single Point Urban Interchange, the streams of left-turning traffic do not cross. Opposing left turns can be made at the same time; with only one set of traffic signals, more vehicles can make the turn and clear the interchange in one traffic signal cycle.

Gradual turns

Single Point Urban Interchanges also allow for long, gradual turns. Larger vehicles like trucks, buses and recreational vehicles have more room to navigate. Traffic moves more smoothly and everyone can breathe a little easier.

 

What about pedestrians and bicycles?

The Single Point Urban Interchange is very safe for pedestrians and bicycles. The pedestrian path is well marked through the use of curbs and medians, different colored materials, or through the use of more substantial structures.

Pedestrians Cyclist Pedestrian with traffic
Click photos to see larger images. Links open in new windows.

Why are Single Point Urban Interchanges more efficient?

A Single Point Urban Interchange moves more traffic through a smaller amount of space. Compare the Single Point to the Cloverleaf design, which takes up a much greater amount of land. The Single Point design makes it easier to build new interchanges within existing state property.

Single Point Interchange Cloverleaf interchange
Single Point Urban Interchange
Cloverleaf Interchange
Click photos to see larger images. Links open in new windows.

How well will the Single Point design fit into the I-64 corridor?

View a Quicktime animation (with audio) of a single point concept design for the Kingshighway interchange Kingshighway Interchange concept
6.1 Mb 2.7 Mb
 
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