When did the SUI (section of independent utility) become a requirement?

[ARMOURERERIC]

Growing up in PA in the 70's, I was always dismayed at all the freeway segments that did not connect to anything:

I-79 between Mt Nebo and 910, but without the connecting rams

Parts of I-476 west of Philly

Now I see references to the SUI

When did that start being a requirement?

[J N Winkler]

As far as I know, SIUs are not a requirement, as such.  SIUs generally develop as the result of a tiering process where a state transportation agency (generally the state DOT) agrees with FHWA to compile a first-tier EIS for a long rural corridor, which is then divided into SIUs which receive their own environmental documents (generally EAs but sometimes EISes for sections in environmentally sensitive terrain) once the first-tier EIS is approved.

There is no requirement for state DOTs to engage in a tiering process.  A state DOT can, for example, try to do hundreds of miles under a single EIS.  Tiering, however, allows the DOT to avoid committing resources to compiling full environmental documentation for every single mile of a corridor which turns out not to be viable; in other words, the eggs are not all in one basket.  It also allows the tasks associated with developing a major corridor to be spread out in time to match the rises and falls in funding availability.

Tiering is possible only if a corridor can be partitioned into independently useful segments.  Endpoints for corridor parts cannot be assigned at random because then any environmental document compiled for a segment thus created could be challenged on the basis that it does not start or end in logical places for purposes of compiling a purpose and need statement, considering indirect impacts, etc.

[NE2]

US 52 in West Virginia is a good example of what happens without SIUs.

[hbelkins]

Kentucky refers to this as "logical termini."

[realjd]

SUI? I'm completely confused. Can someone explains please explain?

[Scott5114]

Basically, it's a method for splitting a long, new-road construction project (notably used on the I-69 extension) into several chunks for the purposes of organizing the management of the project. Each segment ends at a logical point, that is, a connection to another highway, so that if any defined chunk of road were finished before the others it would still be independently useful, thus, a segment of independent utility, or SIU.

I'm sure Mr. Winkler will be along shortly to give a more detailed account of what an SIU is good for in practice, but I believe that's the gist of it.

(Unless you're confused on "SIU" vs "SUI", where I believe the OP just transposed a couple letters by accident.)

[realjd]

Good info, thanks! It makes sense that they would want to do constructin phases that way.

[ARMOURERERIC]

It's like in my OP, they built about 4 miles of I-79 around 1969, that ended about 200 feet short of both Mt Nebo Road and PA 910 with no provision for access, then let it sit for 7 years.  I was thinking that the SIU concept was/had been adopted to stop that practice

[hbelkins]

I drove the new section of what will be US 52 in West Virginia today. It's definitely not really useful as it currently exists. It connects nothing to nothing, basically.

[oscar]

Basically, it's a method for splitting a long, new-road construction project (notably used on the I-69 extension) into several chunks for the purposes of organizing the management of the project. Each segment ends at a logical point, that is, a connection to another highway, so that if any defined chunk of road were finished before the others it would still be independently useful, thus, a segment of independent utility, or SIU.

I thought the SIU concept was also to prevent evasion of environmental requirements (begun in the Nixon era), by splitting a project into tiny pieces which standing alone are environmentally uncontroversial, only the pieces don't make sense except as part of a larger project that would require closer scrutiny.

[J N Winkler]

I thought the SIU concept was also to prevent evasion of environmental requirements (begun in the Nixon era), by splitting a project into tiny pieces which standing alone are environmentally uncontroversial, only the pieces don't make sense except as part of a larger project that would require closer scrutiny.

The legal analysis in this PDF (which covers the "segmentation cases" of the 1970's) tends to confirm what you say.  "Independent utility" was apparently developed as a test by the courts to determine whether roadbuilding agencies sought to evade environmental requirements by chopping a large project into small parts, and codified by FHWA in 1980.

http://www.state.nj.us/turnpike/documents/GSP-MP30-MP80-Widening-Project-NEPA-Independent-Utility-Analysis.pdf

[3467]

IDOT uses it so if they run out of money for a long time they dont have roads to nowhere like they have had many times. In the case of US 67 they have the splits on their webpage. They are much smaller than the EIS units.
They just call them usable segments as opposed to some unusable in the past.