Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[InterstateHistorian]

So I'm driving down 231 in Spencer County, Indiana and I notice these J-Turns that INDOT put in a few years ago and I am wondering if there are any other alternatives that would have done the job better. It's rather odd navigating across one and I wish they would have just put in overpasses. I think there were about 7 deaths from the two intersections that were modified and I understand the J-Turns have helped with that statistically.
Judging by the others that were modified in Wisconsin, they have extra area for big trucks to make a wider turns, and the ones in Dale do not. So they are useless for trucks trying to cross the highway since they can't make the u-turn.
Has anyone seen anything like it or have any alternative ideas that would have made more sense? FYI I am talking about the two SR68 and SR62 intersections with US 231.
 



It is possible that this has already been discussed. Longtime lurker, first time poster.

[jnewkirk77]

The reason they didn't add outside width for trucks is because the median on 231 is 80 feet wide. That's plenty of room to allow an 18-wheeler to make the turns.

[The Ghostbuster]

Wisconsin employs the use of J-Turn intersections on some of their more highly-traveled roadways, such as this one on STH 29 northwest of Green Bay: https://www.google.com/maps/@44.5748193,-88.1666221,777m/data=!3m1!1e3.

[hbelkins]

Kentucky is using these in more places where crossing the four-lane or turning left onto the four-lane has been problematic.

Indiana wants to put some of these on US 31, and there's considerable opposition on this forum. 

[Dirt Roads]

Was wondering what a J-turn was.  I know I'm getting old, but we still call this a "Michigan Left" here in the South.

[jakeroot]

Was wondering what a J-turn was.  I know I'm getting old, but we still call this a "Michigan Left" here in the South.

They are a little different. It's hard to explain, but J-turns seem to allow direct-left turns from the major road, whereas a "Michigan Left" intersection requires traffic, from all directions, to make a U-turn at some point to turn left. Rather than building direct lefts from the main road at the intersection itself, Michigan Left intersections typically have a signal, where only straight-ahead and right turns are permitted; lefts, thus, occur via U-turns, either by going straight or turning right first, and then making a U-turn.

[mvak36]

Was wondering what a J-turn was.  I know I'm getting old, but we still call this a "Michigan Left" here in the South.

They are a little different. It's hard to explain, but J-turns seem to allow direct-left turns from the major road, whereas a "Michigan Left" intersection requires traffic, from all directions, to make a U-turn at some point to turn left. Rather than building direct lefts from the main road at the intersection itself, Michigan Left intersections typically have a signal, where only right turns are permitted; lefts, thus, occur via U-turns, either by going straight or turning right first, and then making a U-turn.

Was typing a reply when I saw yours. You said it better than I ever could. Agree on all the points. I believe all of the ones I've seen in Missouri allow left turns from the main road.

[Dirt Roads]

Was wondering what a J-turn was.  I know I'm getting old, but we still call this a "Michigan Left" here in the South.

They are a little different. It's hard to explain, but J-turns seem to allow direct-left turns from the major road, whereas a "Michigan Left" intersection requires traffic, from all directions, to make a U-turn at some point to turn left. Rather than building direct lefts from the main road at the intersection itself, Michigan Left intersections typically have a signal, where only right turns are permitted; lefts, thus, occur via U-turns, either by going straight or turning right first, and then making a U-turn.

Was typing a reply when I saw yours. You said it better than I ever could. Agree on all the points. I believe all of the ones I've seen in Missouri allow left turns from the main road.

Gotcha.  NCDOT has a silly name for the double left turns combined with the U-turns: Superstreet.  (I think the term Superstreet includes some other type of minor improvements as well).

[jakeroot]

Was wondering what a J-turn was.  I know I'm getting old, but we still call this a "Michigan Left" here in the South.

They are a little different. It's hard to explain, but J-turns seem to allow direct-left turns from the major road, whereas a "Michigan Left" intersection requires traffic, from all directions, to make a U-turn at some point to turn left. Rather than building direct lefts from the main road at the intersection itself, Michigan Left intersections typically have a signal, where only right turns are permitted; lefts, thus, occur via U-turns, either by going straight or turning right first, and then making a U-turn.

Was typing a reply when I saw yours. You said it better than I ever could. Agree on all the points. I believe all of the ones I've seen in Missouri allow left turns from the main road.

Only thing I forgot in my original reply was to be more clear about the signal, in that it allows both straight-ahead and right turns. By saying "only right turns" originally, I may have mistakenly implied that you can only turn right at the signal, when this is incorrect.

I have previously argued at the actual act of a Michigan Left is identical to a J-turn, but the overall setup at a Michigan Left is different.

[froggie]

Spent a considerable number of years in the South, between Virginia and Mississippi (with frequent outlays to adjacent states), and the only time I ever heard the term "Michigan Left" was when I read the old misc.transport.road usenet group.  None of the locals ever used the term, and this was even after NCDOT unleashed their Superstreet concept.


As for the OP's implied question, sure there are other alternatives that would do the job better...but they cost considerably more money.  A J-Turn can typically be put in for a few hundred thousand.  Meanwhile, even in those states with lower construction costs, an overpass will still run a few million at a minimum.  And that's before you include added costs for access connections between the two roads, which in the vast majority of cases will also require right-of-way acquisition.

[hbelkins]

The preferred terminology now seems to be RCUT (restricted crossing U-turn) over J-turn.

Or are there subtle differences between RCUTs, J-turns, and Michigan lefts? (Like roundabouts, rotaries, and traffic circles?)

[Dirt Roads]

Or are there subtle differences between RCUTs, J-turns, and Michigan lefts? (Like roundabouts, rotaries, and traffic circles?)

I think it's like railroads.  They sometimes use the same terminology with different meanings in various parts of the country. 

I was working closely with NCDOT on the Triangle Transit project back from 2003-06, and some of the highway guys referred to the changes to US-1 south of Sanford as "Michigan Lefts".  I can't remember if they were originally installed with only the U-turn functions, but today many of the crossroads have separated left turns instead of RIROs (ergo, Superstreet).  For the record, I like to study these subtle differences in order to "speak the language".

[jakeroot]

Or are there subtle differences between RCUTs, J-turns, and Michigan lefts? (Like roundabouts, rotaries, and traffic circles?)

RCUT and J-turns are the same thing (and are also known as 'superstreets'). I explained above (reply #5) why they are not Michigan lefts, though similar.

[BrianP]

Michigan lefts are definitely separate since they allow the side street to have their thru movement.  But the others are the same.

The RCUT, also referred to as the superstreet intersection or J-turn intersection, is characterized by the prohibition of left-turn and through movements from side street approaches as permitted in conventional designs. Instead, the RCUT intersection accommodates these movements by requiring drivers to turn right onto the main road and then make a U-turn maneuver at a one-way median opening 400 to 1,000 ft after the intersection. Left turns from the main road approaches are executed in a manner similar to left turns at conventional intersections and are unchanged in this design (see figure 2). Left-turn movements from the major road could also be removed at primarily rural unsignalized RCUT designs.

https://www.fhwa.dot.gov/publications/research/safety/09059/

[Buck87]

IIRC, Ohio used the "superstreet" term when describing a project planned for US 35 in Beavercreek and one of the options (not used) for US 33 at Carroll, but has been using "RCUT" for more recently announced projects (such as several that are planned along US 30)

[silverback1065]

why do people hate j-turns so much? they seem to work just fine

[hbelkins]

why do people hate j-turns so much? they seem to work just fine

Mostly because people want a full freeway and would rather spend lots of money on grade-separated interchanges instead of a less-costly measure.

[InterstateHistorian]

Yeah I guess the more I think about it, with cost being a major factor, a J Turn is starting to look better than a traffic light.

[Tom958]

Not too long ago, North Carolina opened a new four-mile bypass of Troy. I've seen some photos and a video of it on Facebook, and my possibly-erroneous impression is that it has no conventional intersections, only r-cuts and one very economically-constructed interchange (https://www.google.com/maps/@35.3499786,-79.8750047,351m/data=!3m1!1e3). The r-cut at the eastern end of the bypass is signal controlled, but the others aren't. The really weird thing is that the interchange wasn't in the original plans from 2014, which our friend Jonathan Winkler downloaded.  Also, the bridge was of a very cheap-looking design that I hadn't seen anywhere else, like one that was used mainly for stream crossings rather than grade separations. I don't think I'll ever make it by there myself, so I hope that Google will update their imagery there before too long.