Improving Upon the Humble TUDI

[kernals12]

A tight urban diamond interchange is one where the two intersections are so close together that the left turn lanes overlap like this:


One simple change that greatly improves capacity is to have the left turn lanes swapped like this:

This allows left turns to be made in both directions from the arterial to the freeway simultaneously.

A further improvement is to put the left turn lanes all the way on the left in a grade separated version of a Continuous Flow Intersection.

2 of these have been built in San Marcos, TX on I-35. In both cases, they simply adapted the existing Texas U-turns to serve as the displaced left turn lanes

Hopefully they get incorporated in more places

[kphoger]

A further improvement is to put the left turn lanes all the way on the left in a grade separated version of a Continuous Flow Intersection.



2 of these have been built in San Marcos, TX on I-35. In both cases, they simply adapted the existing Texas U-turns to serve as the displaced left turn lanes

Specifically–for those interested–they are at TX-80 (Exit 205) and Loop-82 (Exit 206).  The latter is one-sided, meaning only one direction of the cross-road has its left turn lane displaced.

[thspfc]

So the difference between this and a DDI is that the rams don't extend as far laterally from the freeway, meaning that this is useful in tight places where a DDI is not possible?

[CtrlAltDel]

So the difference between this and a DDI is that the rams don't extend as far laterally from the freeway, meaning that this is useful in tight places where a DDI is not possible?

Additionally, in a DDI, the through lanes also move to the left.

[pianocello]

One simple change that greatly improves capacity is to have the left turn lanes swapped like this:

This allows left turns to be made in both directions from the arterial to the freeway simultaneously.

This configuration was used at the I-4 and FL 436 interchange north of Orlando while they were building the SPUI that's currently there. It's a bit hard to capture on Street View, but you might be able to see how it worked here if you go back in time to late 2019-early 2020.

Unfortunately, they missed the opportunity to improve traffic flow; The signal timing and phasing was the same as if it was a standard tight diamond. It was pretty aggravating, but I understand not spending the resources to develop a new signalization plan for a temporary situation.

[CardInLex]

One simple change that greatly improves capacity is to have the left turn lanes swapped like this:

This allows left turns to be made in both directions from the arterial to the freeway simultaneously.

I want this set up at this interchange so bad. It would not even be that difficult for INDOT to implement.
https://goo.gl/maps/kpL5xCEN5MiKWAhB8

[Ned Weasel]

One simple change that greatly improves capacity is to have the left turn lanes swapped like this:

This allows left turns to be made in both directions from the arterial to the freeway simultaneously.

This would probably be a good idea at US 69 and 151st Street in Overland Park, Kansas, except with the lanes on the arterial road being doubled.  (Here: https://goo.gl/maps/SRcgdDZqi7YXYpXG6 )