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Single Point Urban Interchanges

  1. What are Single Point Urban Interchanges?
  2. How do they work?
  3. What do they look like when driving?
  4. Frequently asked questions
  5. The future

What are single point urban interchanges?

Single point urban interchanges help move large volumes of traffic through limited amounts of space safely and efficiently. These interchanges are a great way to maximize the flow of traffic where streams of traffic merge or separate.

The single point urban interchange manages traffic very effectively. This interchange, also know as an X-interchange or an Urban Diamond is being used extensively in the reconstruction of existing freeways as well as constructing new freeways. This simple design makes the most of safety, capacity and efficiency.

How do single point urban interchanges work?

Example of Single Point IntersectionSingle point urban interchanges link a major thoroughfare with a freeway. With the example to the left, the interchange links the arterial street on top with a freeway that passes underneath.

The name "Single Point" refers to the fact that all through traffic on the arterial street, as well as the traffic turning left onto or off the interchange, can be controlled from a single set of traffic signals.  In the example above, all the traffic signals are located at a single point in the middle of the interchange. For a larger-sized sequence of the process, click here (Use Page Up or Page Down keys to navigate).

The single point urban interchange sequence:

  • The first cycle is for through traffic on the arterial street; this is the traffic that is not turning.
  • Cycle two is for traffic leaving the freeway and turning left onto the arterial street.
  • Cycle three is for traffic leaving the arterial street and turning left onto the freeway.

This is what it looks like in real life, during peak traffic hours. (Use Page Up or Page Down keys to navigate).

What does a single point urban interchange look like on the ground?

Figure 1 Figure 2 Figure 3
These photos show a view on the exit ramp, leaving the freeway and approaching a single point urban interchange. (Click on each image for a larger view)
When you get to the top of the ramp, the roadway splits to allow for left turns and right turns.  When you make a left turn through the interchange, you will be moving on a long diagonal, with opposing traffic on your right. Finding your way through the interchange is simple - you just follow the painted lines.

Frequently asked questions

The future

MoDOT is committed to doing more than simply adding more lanes or using more space today to make the most of our highways for tomorrow. We must use the latest technology and most advanced engineering techniques.  The Single Point Urban Interchange brings increased safety, capacity and efficiency to urban travel. Where appropriate, we will incorporate these designs into future interchanges.

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