Why are states downgrading interchnges?

[US 41]

I was driving in Indy and realized that at I465 and Sam Jones Pkwy (former Airport Expressway) INDOT has put a diamond there.
What was wrong with the old interchange? http://www.in.gov/indot/images/MPA465_SamesJonesExpressway_2012.jpg

That's not the only place in Indy where it's gotten worse. INDOT has replaced cloverleafs with partial cloverleafs. I don't see how this is a upgrade. I don't think it's an upgrade if traffic has to stop where it didn't before. I know some are going to say it's to busy for a cloverleaf, but what I have to say is people need to quit being stupid, pay attention, and learn how to drive.

There are also other places where interchanges are getting "downgraded". I don't understand why DOT's want to stop traffic.

[tradephoric]

That's not the only place in Indy where it's gotten worse. INDOT has replaced cloverleafs with partial cloverleafs. I don't see how this is a upgrade. I don't think it's an upgrade if traffic has to stop where it didn't before. I know some are going to say it's to busy for a cloverleaf, but what I have to say is people need to quit being stupid, pay attention, and learn how to drive.

This might be an interesting thread to you.  It describes the benefits of the parclo B4 partial cloverleaf design vs. the parclo A4 in respect to reducing driver delay.  Out of curiosity, what design was selected in Indy when converting the full cloverleafs to partial cloverleafs?

https://www.aaroads.com/forum/index.php?topic=7967.msg182859#msg182859

[jeffandnicole]

I know some are going to say it's to busy for a cloverleaf, but what I have to say is people need to quit being stupid, pay attention, and learn how to drive.

Right.  Because that works so well to solve the problem *everywhere* else.

An interchange near me underwent such a transformation.  I'm pretty sure it was designed by that guy that finished at the bottom of the class but just good enough to pass.  2 of the issues I have (not include the addition of traffic lights) at this particular interchange: The traffic light was designed with a crosswalk button 3 feet beyond a guardrail.  And the very obvious low point in the roadway doesn't have a drainage inlet, subjecting the area to flooding.

[vdeane]

In PA there's the PA 581/US 15 interchange, where traffic bypassing Harrisburg traveling between DC and western NY now has to stop at a light.  NYSDOT also recently installed a traffic light at what was once loop ramps on Burrstone Road in Utica.

[hbelkins]

Getting rid of weaving movements is a Good Thing.

[Urban Prairie Schooner]

I was driving in Indy and realized that at I465 and Sam Jones Pkwy (former Airport Expressway) INDOT has put a diamond there.
What was wrong with the old interchange? http://www.in.gov/indot/images/MPA465_SamesJonesExpressway_2012.jpg

That's not the only place in Indy where it's gotten worse. INDOT has replaced cloverleafs with partial cloverleafs. I don't see how this is a upgrade. I don't think it's an upgrade if traffic has to stop where it didn't before. I know some are going to say it's to busy for a cloverleaf, but what I have to say is people need to quit being stupid, pay attention, and learn how to drive.

There are also other places where interchanges are getting "downgraded". I don't understand why DOT's want to stop traffic.

I am guessing, in this case, it is because traffic counts at this location have declined since this is no longer the main access to the IND airport terminal, and thus the interchange is being rebuilt to a lower design standard. I do agree with you, though, in that it does not seem like a good idea to place at-grade intersections at what is essentially a freeway to freeway junction.

Also, it would appear that cloverleafs (cloverleaves?) are falling out of favor with state DOTs due to the weaving issues inherent in that design. Louisiana DOTD just completed rebuilding the I-10/Causeway Boulevard interchange to remove the most egregious merging/weaving choke points, essentially rendering it a weird variant of cloverleaf with flyover ramps.

[tradephoric]

Getting rid of weaving movements is a Good Thing.

Getting good signal progression along a corridor is a good thing too.  Engineers could achieve both if they just designed more Parclo B4s!

[getemngo]

Trying to decide if I should use this thread as an opportunity to complain about SPUIs...

Also, it would appear that cloverleafs (cloverleaves?) are falling out of favor with state DOTs due to the weaving issues inherent in that design. Louisiana DOTD just completed rebuilding the I-10/Causeway Boulevard interchange to remove the most egregious merging/weaving choke points, essentially rendering it a weird variant of cloverleaf with flyover ramps.

Wow, that is a weird one.

[hbelkins]

Trying to decide if I should use this thread as an opportunity to complain about SPUIs...

Any particular SPUI you have in mind? 

Actually, I don't have any problems with them. What do you dislike about them?

[Mergingtraffic]

CT has restriped certain areas and in the process downgraded the lanes in a few spots.  The reson being there isn't as muc traffic to warrant it.

I-84 EB Waterbury between Exit 21 & 22, the aux lane was taken out and now there isn't enough merge time for the vehicles at the preceding on-ramp.

Also, the new Exit 26 off-ramp designed and striped for 2-right turn lanes and 1 left turn lane was restriped with one right turn lane and one left turn lane.  Why? Idk

However, if they can downgrade why can't they upgrade!?  There are many places to add in turn lanes and not having to widen the road but it never gets done. 

not too many interchanges have been down graded here.  I-395 and CT-82 was reconstructed and they took away some free movements with stoplights. 

[tradephoric]

Trying to decide if I should use this thread as an opportunity to complain about SPUIs...

Heck, go for it!  I think it's relevant to this thread as the OP is mentioning having to stop after the upgrade when before they never had to.  You don't run across many unsignalized SPUI's!  On the other hand, here is an example of an unsignalized parclo B4 interchange along a 6-lane boulevard in Florida. 

https://maps.google.com/?ll=26.06264,-80.35486&z=16&t=h

[getemngo]

Actually, I don't have any problems with them. What do you dislike about them?

I don't hate SPUIs, and I do think they're really good for replacing diamonds in tight spaces with high traffic counts. It's also really fun to zip across all those lanes once the light turns green when you're exiting and turning left. No second intersection!

But they're called Single Point Urban Interchanges. In urban areas, they're great. Where there's more space, I (like Tradephoric) would prefer a parclo.

I'm from a state where 1) permissive left turns are very common, and 2) the Michigan Left reduces the number of phases needed at a lot of signals. So I'm used to short lights. At a SPUI, I feel like the red light lasts forever, especially when turning left to enter the freeway - and it can screw up the timing of nearby signals. Admittedly, "They run counter to what I feel are my state's practices, but they're probably great with your state's practices" may not be the best argument.

However, I've also seen a number of head-on collisions from traffic exiting SPUIs, and it isn't fun to cross an angled, unsignalized entrance ramp as a pedestrian, so I'm a bit concerned about their safety record too. It's hard to find another type of intersection with that much uncontrolled pavement.

[Brandon]

Trying to decide if I should use this thread as an opportunity to complain about SPUIs...

Heck, go for it!  I think it's relevant to this thread as the OP is mentioning having to stop after the upgrade when before they never had to.  You don't run across many unsignalized SPUI's!  On the other hand, here is an example of an unsignalized parclo B4 interchange along a 6-lane boulevard in Florida. 

https://maps.google.com/?ll=26.06264,-80.35486&z=16&t=h

Of course, a B4 parclo doesn't really need signals like an A4 does.

However, that said, A4s without signals do exist.  US-51/US-51 Business and I-74 in Bloomington, Illinois.  Streetview.

Here's a SPUI without signals: IL-137 at Grand Avenue, Waukegan, Illinois.  Streetview: Nbd exit ramp.

The half-SPUI to the north is also controlled with stop signs.

[SD Mapman]

I was driving in Indy and realized that at I465 and Sam Jones Pkwy (former Airport Expressway) INDOT has put a diamond there.
What was wrong with the old interchange? http://www.in.gov/indot/images/MPA465_SamesJonesExpressway_2012.jpg

That's not the only place in Indy where it's gotten worse. INDOT has replaced cloverleafs with partial cloverleafs. I don't see how this is a upgrade. I don't think it's an upgrade if traffic has to stop where it didn't before. I know some are going to say it's to busy for a cloverleaf, but what I have to say is people need to quit being stupid, pay attention, and learn how to drive.

There are also other places where interchanges are getting "downgraded". I don't understand why DOT's want to stop traffic.

Trying to decide if I should use this thread as an opportunity to complain about SPUIs...

Well, SDDOT isn't. In fact, they're moving the other way (SPUIs for everyone!). I think about 1 interchange per year has been converted to a SPUI in the past few years, with one more in a couple years.

[cpzilliacus]

Getting rid of weaving movements is a Good Thing.

H.B, you beat me to it.  It isn't always an issue, but "full" cloverleafs often have problems with weaving (since the weave area is by definition pretty limited). 

So removing some of the cloverleaf ramps and replacing them with signalized ramps (example here) in Maryland, or doing other massive reconstruction (example here (also Maryland)) or an almost equally massive retrofit while keeping the cloverleaf (example here  in Virginia) does help.

[Mr_Northside]

But they're called Single Point Urban Interchanges. In urban areas, they're great.

I have also heard them referred to as Single Point Diamond Interchanges as well.  When PennDOT built it's first at the junction of US-22/PA-66 in Delmont (well over a decade ago now, holy shit...) they used that term a lot. That interchange also replaced a very tight cloverleaf.

[Big John]

I also seen them called Single Point Urban Diamond, but not that common.  This one's abbreviation spells a real word.

[roadman65]

New Jersey had one interchange that was changed to an at grade intersection.  US 130 and NJ 33 in East Windsor had a directional interchange that was replaced with a signalized intersection.

Maryland replaced one interchange along the Bel Air Bypass of US 1 that was designed to be an interchange with stubs and dirt fills, but when it was extended to bypass Hickory the stubs were flattened and the road lowered to meet US 1 Business at grade.

US 1 & 9 and NJ 35 in Woodbridge was converted to a diamond from its original cloverleaf form, however I think that had to do with weaving issues.

FL 482 in Belle Isle, FL used to have a free flowing ramp that took motorists on to FL 528 EB from its eastern terminus before Boggy Creek Road was extended there.  When Boggy Creek Road was built a signalized intersection not only was erected, but motorists that went from FL 482 EB to FL 528 EB in a directional interchange now have to enter the frontage road for FL 528 to access its ramp.

[vtk]

US 40 at OH 158 used to be a partial interchange.  This was because it was for a few years the west end of a section of I-70.  After more of I-70 was finished and this was no longer part of it, the interchange remained for a couple of decades before being downgraded.

[tradephoric]

WI 124 at WI 178 use to be grade separated.  It's now a partial triple lane roundabout. 

https://maps.google.com/?ll=44.920969,-91.379862&spn=0.00303,0.003449&t=h&z=18

[mukade]

I was driving in Indy and realized that at I465 and Sam Jones Pkwy (former Airport Expressway) INDOT has put a diamond there.
What was wrong with the old interchange? http://www.in.gov/indot/images/MPA465_SamesJonesExpressway_2012.jpg

That's not the only place in Indy where it's gotten worse. INDOT has replaced cloverleafs with partial cloverleafs. I don't see how this is a upgrade. I don't think it's an upgrade if traffic has to stop where it didn't before. I know some are going to say it's to busy for a cloverleaf, but what I have to say is people need to quit being stupid, pay attention, and learn how to drive.

There are also other places where interchanges are getting "downgraded". I don't understand why DOT's want to stop traffic.

The original interchange at Airport Expy./Sam Jones Expy. looked great on paper but it was not the safest one. The ramp from SB I-465 to EB Sam Jones was very tight. When the terminal moved, you were left with a road that ended a few hundred feet west of I-465 that no longer carried a high volume of traffic so I don't see how a very costly freeway to freeway interchange should have been justified there. Although I don't live down there, I think what they did makes very good sense. Money is limited, and other interchanges on I-465 needed costly improvements much more - some have been improved, and others (like I-465/I-69) are still waiting.

As for the cloverleaf topic, I lived near the I-65/US 30 interchange for years. US 30 is both a major intercity as well as a major local road so it has a lot of trucks and cars. As the area built up, the weaving became very dangerous and the original design definitely slowed down traffic. INDOT rebuilt the interchange about ten years ago so it is now a parclo (A4). Look at Google Maps.

Note that the EB US 30 to NB I-65 loop ramp has been widened, and there are triple left turn lanes/double right turn lanes on to US 30. Also, the two loop ramps are separated from the mainline US 30 so they avoid the traffic lights. Although having two more lights is a pain, this is overall a much better design. I can't imagine how bad it would be if they had left it a full cloverleaf.

Also, two miles north, INDOT changed the 61st Avenue diamond interchange into another A4 parclo. I don't consider any of the INDOT interchanges changes (which have been many) to be downgrades. In the end, they are safer and can carry higher volumes of traffic.

[vdeane]

The current cloverleaf at I-81 and NY 7 is going to be downgraded to some variant of diamond or folded diamond.

[roadman65]

The US 71 & US 59 and I-30 interchange in Texarkana was a cloverleaf turned into a diamond, but a downgrade I would exactly not say so.  All they did was eliminate the weaving that originally existed. 

Now if you look at it for the signal aspect, it may be a downgrade cause you now have to wait at a signal instead of free flowing as you were for some time before.  However, signals are being erected all throughout many states at typical intersections where for years we flowed smoothly and now have to stop for a minuet or two along our travel paths.  So this is basically no different than that.

[tradephoric]

Now if you look at it for the signal aspect, it may be a downgrade cause you now have to wait at a signal instead of free flowing as you were for some time before.  However, signals are being erected all throughout many states at typical intersections where for years we flowed smoothly and now have to stop for a minuet or two along our travel paths.  So this is basically no different than that.

That's true, but there are designs that reduce the likelihood of getting stopped at a red light.  The most obvious example would be a one-way street.  Signals along a one-way street can be timed to provide a wave of green lights for drivers (you may have to wait 1-minute at a traffic signal, but once you get your green you might drive through 50 green lights).  Another design that improves signal progression is known as the superstreet.  A superstreet essentially splits up a two-way road into two one-way streets making good 2-way signal progression possible.  If you look at a parclo B4 interchange it looks a lot like a superstreet:

Superstreet in Troy, Michigan:


Parclo B4 in Dallas, Texas:

[US 41]

That's not the only place in Indy where it's gotten worse. INDOT has replaced cloverleafs with partial cloverleafs. I don't see how this is a upgrade. I don't think it's an upgrade if traffic has to stop where it didn't before. I know some are going to say it's to busy for a cloverleaf, but what I have to say is people need to quit being stupid, pay attention, and learn how to drive.

This might be an interesting thread to you.  It describes the benefits of the parclo B4 partial cloverleaf design vs. the parclo A4 in respect to reducing driver delay.  Out of curiosity, what design was selected in Indy when converting the full cloverleafs to partial cloverleafs?


https://www.aaroads.com/forum/index.php?topic=7967.msg182859#msg182859

Parclo A4 I think. The interchange I'm talking about is at US 40 / 465 on the west side of Indy.