# Which type of junctions are common in your country, and which is your preferred type?



## NCT (Aug 14, 2009)

I haven't found another thread on this topic but if there is feel free to lock or merge this thread.

I recently went on a road trip through France to Spain and I noticed how motorway junctions are distinctly different in France, Spain and in the UK.

In France and Spain where motorways are tolled the trumpet type is the most cost-effective and indeed most common. 










Usually a motorway-to-road interchange consists of a link road connecting the two, with a trumpet interchange at the motorway end and a flat junction at the ordinary-road end. An example of such an interchange is this:

http://maps.google.co.uk/?ie=UTF8&ll=48.178092,4.439077&spn=0.006424,0.013711&t=k&z=16

Even motorway to motorway interchanges seem to consist of two trumpets connected by a link road:

http://maps.google.co.uk/?ie=UTF8&ll=48.061819,2.667189&spn=0.012878,0.027423&z=15


In the UK by far the most common is the roundabout, and dumbell and three-level roundabout junctions easy to find too. A few really busy junctions are of the more free-flowing whirlpool or 4-level stack types. 

Roundabout:










Dumbell:










Three-level roundabout:










Whirlpool:










Four-level stack:










In China most motorway to road interchanges seem to be of the trumpet type due to toll-booth considerations. Motorway to motorway junctions are mostly 4-level stack, whirlpool or (partial-)cloverleaves.

Parcial cloverleaves:










Which type of junctions are prevelent in your country and which ones are your favourite?


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## ChrisZwolle (May 7, 2006)

France doesn't have many 4-way interchanges, most are 3-ways. Therefore, there are almost no cloverleafs in France, or stacks for that matter. Germany has more like a grid system, and cloverleafs are far more common. Cloverleafs are also common in the Netherlands. 

The British oval roundabout on top of a motorway is generally rare in mainland Europe. As far as I know, we have only two in the Netherlands (Rottepolderplein on A9 and St. Joost on A2)


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## Bartolo (Sep 20, 2004)

In Ontario, every interchange is a Parclo and all 4 way interchanges between freeways are cloverstacks expect the 400 and 407 is a stack


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## Danielk2 (Jun 2, 2009)

*Parclo = Partial Cloverleaf


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## El Tiburon (Mar 21, 2010)

In the United States there is a little bit of everything and they vary not only state by state but county by county. Budgets are a very big consideration in the design.

Where I live, in South Florida, we had cloverleaves and partial cloverleaves when expressways began to be built between the 1950's to the 1970's.

As the population grew and more expressways were built or widened, the interchange designs became more ad hoc according to the location and the availability of land. Some of the ramps in recently-built interchanges end in intersections with traffic lights, which slows down the traffic that, in the past, effortlessly merged down the cloverleaf ramps.

At the Golden Glades interchange, where Interstate 95, State Road 826 (Palmetto Expresway), State Road 7, US 441, State Road 9 and the Florida Turnpike join, the design is like strands of spaghetti or silly string thrown together over four decades in a poorly thought out ad hoc design:









There is also an interchange in far western Broward County where Interstates 75 joins Interstate 595, State Road 869 (Sawgrass Expressway) and State Road 84 which is a mix between whirlpool and multilevel stack designs:









In both of those interchanges, at least three limited-access highways (expressways) join with each other and with regular open access roads.


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## ChrisZwolle (May 7, 2006)

Spain has a shitload of incomplete interchanges. Almost every village along an Autovía has at least two partial interchanges where you can only go on two directions on both sides of town.


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## El Tiburon (Mar 21, 2010)

I prefer the full cloverleaf design because it doesn't interfere with the free flow of traffic (provided that it has adequate merging zones at the tangential points of the circular ramps).

Here is an example of a perfectly good full cloverleaf interchange that was converted into a partial cloverleaf (with traffic lights that hinder traffic) when the expressway was widened and the ramps redone. It's in Miami, Florida, USA at the intersection of State Road 826 (also know as the Palmetto Expressway) and State Road 90 (also known as US 41, Tamiami Trail, SW 8 Street, and Calle Ocho).

Before the remodeling of the interchange, you could connect from any direction in one road to any direction in the other road. See the area in 2002:









Now, with the elimination of two ramps, you have to wait at traffic lights to go from northbound SR 826 to westbound SR 90 and from westbound SR 90 to southbound SR 826. In addition, you can no longer make U-turns using the ramps. See the interchange in 2010:


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## nerdly_dood (Mar 23, 2007)

I like to call stacks and stuff like this "concrete knots"


El Tiburon said:


>


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## Haljackey (Feb 14, 2008)

Just about everything here is a parclo:









But I prefer stack... but its kinda expensive and excessive to build one at every single interchange.:lol:


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## ChrisZwolle (May 7, 2006)

Stacks are not necessarily larger in area than a cloverleaf with a collector/distributor setup. Only if you are gonna include more than 4 levels, it becomes larger because you need longer ramps with a wider curvature.


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## TheCat (Apr 21, 2006)

Haljackey said:


> Just about everything here is a parclo:
> ...
> 
> But I prefer stack... but its kinda expensive and excessive to build one at every single interchange.:lol:


Heh stacks aren't really built between a regular road and a freeway (like in your picture). Parclos are a great compromise IMO. All entrances to the freeway are free-flowing, but the exits have traffic lights.

Of course, between freeways stacks have the most capacity, but as you said, they are very expensive to build.


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## Exethalion (Dec 23, 2008)

UK Motorway junctions are almost overwhelmingly Roundabout type (roundabout above or below the motorway. We just seem to have an obsession with roundabouts, probably because they work so well! (So long as they aren't signal controlled).

We have very few diamond junctions like those seen in the USA.










The few situations where two motorways intersect in a 4-way junction in the UK are covered by 4-level stacks or turbines.


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## Fargo Wolf (Oct 23, 2009)

In western Canada, Diamond type interchanges predominate. Exit the motorway at the slip road and travel to the junction with the cross road. Major ones for the most part, have traffic lights. The advantage to these types, aside from their simplicity, are, that if required, traffic can be diverted down the slip road, and up the entrance ramp on the far side.


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## Paddington (Mar 30, 2006)

We've had lots of threads on this. In america, the most common expressway - road interchanges, especially in the suburban areas, are diamonds. Sometimes a "trumpet" is used instead. Common expressway interchanges include the cloverleaf and various types of partial or full stack interchanges.


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## Haljackey (Feb 14, 2008)

Haljackey said:


> But I prefer stack... but its kinda expensive and excessive to build one at every single interchange.:lol:





ChrisZwolle said:


> Stacks are not necessarily larger in area than a cloverleaf with a collector/distributor setup. Only if you are gonna include more than 4 levels, it becomes larger because you need longer ramps with a wider curvature.





TheCat said:


> Heh stacks aren't really built between a regular road and a freeway (like in your picture). Parclos are a great compromise IMO. All entrances to the freeway are free-flowing, but the exits have traffic lights.
> 
> Of course, between freeways stacks have the most capacity, but as you said, they are very expensive to build.


The thread asked me which my preferred type is. My answer is stack, even if it is with a minor road :nuts:. No stop lights, weaving or loop ramps. Realistically that makes absolutely 0 sense because they are only needed with major junctions with another highway if the conditions are right.


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## NCT (Aug 14, 2009)

Stacks are no doubt one of the best for very busy junctions. IMO roundabouts are probably the best for other junctions - very simple to navigate and no flat junctions (in the traditional sense), though most importantly they give you nice straight sliproads that allow you to accelerate to 70mph as you approach the merge lane. The French junctions I find very disorientating, and the slip roads are often very curvy meaning you need to build up speed *on* the merge lane.


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## Jonesy55 (Jul 30, 2004)

Why do so few places like the roundabout junctions that are so common here? What are the disadvantages of this type of junction?


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## ChrisZwolle (May 7, 2006)

^^ You need to construct two bridges over the motorway, which - in general - is more expensive than an interchange with one bridge. You also see a lot of interchanges with two roundabouts at either side and one bridge in between across the motorway.


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## Jonesy55 (Jul 30, 2004)

Those are 'dumbell' junctions aren't they?

I'm guessing a 'roundabout on top' is still much cheaper than a stack or turbine though and uses less land than any cloverleaf variant.


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## Paddington (Mar 30, 2006)

In Ohio, they're replacing a number of cloverleaf interchanges with these:


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## Snowguy716 (Apr 10, 2009)

In Minnesota, the cloverleaf reigns supreme. I don't know if it's because stacks can be dangerous during winter... or they're just cheap... but many of the cloverleafs are much too small for the amount of traffic they handle and so there are always traffic jams around them.

The worst is perhaps the cloverleaf at I-494 and I-35W at the Bloomington/Richfield line.

MNDot has proposed a reconstruction with a "half stack" that would be a hybrid stack/cloverleaf with stack ramps for traffic leaving I-35W and cloverleaf ramps for traffic leaving I-494. While the circles would still slow traffic on 494, it would eliminate the weaving done with circles on both sides with traffic both entering and exiting the freeway over the relatively small bridge.










Courtesy of MNDot


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## NCT (Aug 14, 2009)

Jonesy55 said:


> Why do so few places like the roundabout junctions that are so common here? What are the disadvantages of this type of junction?


I think one major reason is that motorways are tolled in most countries so it makes sense to have trumpet junctions where all traffic is funnelled into one toll station. For motorway to motorway interchanges you should really look beyond roundabouts to stacks or cloverleafs (or its variants) anyway.


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## kalle_sg (Apr 27, 2008)

ChrisZwolle said:


> The British oval roundabout on top of a motorway is generally rare in mainland Europe. As far as I know, we have only two in the Netherlands (Rottepolderplein on A9 and St. Joost on A2)


Interchanges with roundabouts occur in Sweden - especially in urban areas and on the newly constructed roads. Like this, E4 around Uppsala:









Apart from that, there are many different types. The most popular, I think, are diamonds, trumpets and something like that (E4 around Tystberga):









Or a combination of a diamond and that one above (E4 past Hölö):









But that only concerns interchanges with normal roads. Motorway/motorway interchanges... well, there aren't many of those in Sweden. And each of them is unique


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## Haljackey (Feb 14, 2008)

Snowguy716 said:


> In Minnesota, the cloverleaf reigns supreme. I don't know if it's because stacks can be dangerous during winter... or they're just cheap... but many of the cloverleafs are much too small for the amount of traffic they handle and so there are always traffic jams around them.
> 
> The worst is perhaps the cloverleaf at I-494 and I-35W at the Bloomington/Richfield line.
> 
> ...


Probably because these junctions were constructed a long time ago and have not been upgraded. Cloverleafs are actually much more dangerous than stacks because of the crazy weaving they cause and the chance of rollovers on those tight loop ramps.

By half stack, I assume you mean a cloverstack. Its a good compromise because you get rid of all the weaving and two of the loop ramps (flyovers are much straighter and thus less chance of a rollover). 

I don't know if stacks can be dangerous during winter... I could see the flyovers becoming slippery but they are used to a good degree here in Ontario and the rest of Canada. As long as a good de-icing system or whatnot is built into the flyover or gets regular attention deicing trucks, it should be fine.


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## Gil (Mar 11, 2005)

Haljackey said:


> I don't know if stacks can be dangerous during winter... I could see the flyovers becoming slippery but they are used to a good degree here in Ontario and the rest of Canada. As long as a good de-icing system or whatnot is built into the flyover or gets regular attention deicing trucks, it should be fine.


The problem in the winter lies in the placement of the snow when the plows go through. The snow usually winds up in the shoulder lanes of the ramp and given the right conditions the snow can harden into ice. Now someone taking the ramp a little too fast can mount the snowbank and become airborne off the ramp or teeter on the guardrail if the snow can't support the full weight of the impacting car. It's happened more than once around Toronto when you get an extended cold snap following a significant snow storm.


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## Paddington (Mar 30, 2006)

I've heard a different explanation. I've heard that the ground never gets too cold and acts as a big heat sink. Any road that's in the air won't have this benefit and will be more prone to ice. 4 level stack interchanges especially have very long ramps, very high in the air. That said, Detroit has 2-3 four level stack interchanges and Cleveland has 3. Many cities much further to the South including Atlanta, Washington, Philadelphia have less than this.


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## piotr71 (Sep 8, 2009)

NCT said:


> ... though most importantly they give you nice straight sliproads that allow you to accelerate to 70mph as you approach the merge lane


.
Although, because of the shape of those slip-roads, which are mainly unparallel to the carriageway, drivers trying to merge with the traffic very often slowing down instead of fluently speed-up on their end . Reason for that is lack of opportunity to see in car's side mirror a lane they want to merge into, so driver has to turn his head. On junctions with A roads, proper merging lanes almost do not exist. 



> The French junctions I find very disorientating, and the slip roads are often very curvy meaning you need to build up speed *on* the merge lane.


Merging lanes are known, I presume anywhere in the Continental Europe, as this part of road where you are to build your speed efficiently to merge into motorway safely. They are in most cases parallel to motorway, so you can see traffic in your mirrors and have opportunity to jump into first lane in most suitable time not causing others slowing down. 

French build roundabout style junctions, as well. However, they are luckily equipped with properly shaped, long merging lanes. The one below from here:

http://maps.google.co.uk/maps?f=q&source=s_q&hl=en&q=Dunkirk,+Nord,+Nord-Pas-de-Calais,+France&sll=52.348442,5.623434&sspn=0.002048,0.005681&ie=UTF8&cd=1&geocode=FbS4CgMddEQkAA&split=0&hq=&hnear=Dunkirk,+Nord,+Nord-Pas-de-Calais,+France&ll=50.973481,2.224431&spn=0.016889,0.045447&t=k&z=15










And the length of the merging lane. 










My favorite junctions? All which let me go through without stopping.


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## Paddington (Mar 30, 2006)

Roundabout interchanges still suck though.


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## El Tiburon (Mar 21, 2010)

piotr71 said:


> .
> My favorite junctions? All which let me go through without stopping.


That should be required for all junctions. No junction should come with traffic lights or stop or yield signs.


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## NCT (Aug 14, 2009)

piotr71 said:


> .
> Although, because of the shape of those slip-roads, which are mainly unparallel to the carriageway, drivers trying to merge with the traffic very often slowing down instead of fluently speed-up on their end . Reason for that is lack of opportunity to see in car's side mirror a lane they want to merge into, so driver has to turn his head. On junctions with A roads, proper merging lanes almost do not exist.


On British motorways most sliproads are dead parallel to the main carriageway, unlike on trumpets where the sliproad is a (sometimes very tight) loop until it becomes the merge lane. It is true however that many merge lanes on A-roads do not have adequate enough merge lanes.



> Merging lanes are known, I presume anywhere in the Continental Europe, as this part of road where you are to build your speed efficiently to merge into motorway safely. They are in most cases parallel to motorway, so you can see traffic in your mirrors and have opportunity to jump into first lane in most suitable time not causing others slowing down.


Most merge lanes are about 200m long. Getting on a motorway from a roundabout junction with nice straight parallel slip roads you are already at 60-70mph so have the whole 200m in which to join the main carriageway. On a trumpet you need to use the first 100-odd metres just to get up to speed, leaving you only with the next 100m in which to join in.


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## ChrisZwolle (May 7, 2006)

^^ In that context, junctions with the crossing road on top of the motorway are always better. You can use the downhill ramp to pick up speed to merge properly, and use the uphill ramp to slow down to intersect with the crossing road.


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## scotdaliney (Dec 1, 2006)

Perth uses Diamonds everywhere. They can get very clogged.
While we don't have any freeway to freeway junctions yet, some are in the planning stage, all which seem to be like this-


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## NCT (Aug 14, 2009)

ChrisZwolle said:


> ^^ In that context, junctions with the crossing road on top of the motorway are always better. You can use the downhill ramp to pick up speed to merge properly, and use the uphill ramp to slow down to intersect with the crossing road.


I know of a few junctions where the roundabout of dumbell is placed under the motorway so the slope of the sliproads are the wrong way round. I don't think this really the an issue though since length and shape of the sliproad are much more important IMHO.


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## jandeczentar (Aug 14, 2009)

Mercifully we don't have a lot of cloverleaf junctions in the UK. As far as I know there are only 2 in Britain: 1 in Livingston, 1 in Redditch and neither on a motorway. The weaving between incoming and outgoing traffic is dangerous, especially at peak periods. There are a few partial ones like the M6/M62 between Liverpool and Manchester, the M25/M40 NW of London or the M4/A329(M) SE of Reading.

There also aren't a lot of motorway-to-motorway trumpet interchanges like you see in continental Europe. The preferred method of motorway termination is the Y-interchange and there are many to chose from. The M1/M18 E of Sheffield, the M5/M6 NW of Birmingham and the M8/M9 W of Edinburgh (to name 3). There are also wierd versions such as the A1(M)/M62 near Pontefract, M3/M27/A33 N of Southampton or the M60/M61/A666 NW of Manchester where extra bits get entangled with the slip-roads.

Then there is the 3-level stacked 'whirl,' a 4-way, free-flow interchange but not as expensive as a 4-level stack. Examples of this include the M3/M25 SW of London, the M11/M25 NE of London and the M60/M62/M602 W of Manchester. There are strange versions of this as well, like the M6/M56/A50 junction between Chester and Manchester.

There are only 3 of the orthodox 4-level stack junctions in Britain (where the slip-roads cross over each other in the middle). The M4/M5 N of Bristol, the M4/M25 W of London and the M23/M25 S of London.

By far the biggest junction in Britain connects the M6/A38(M)/A5127 N of Birmingham. Known as "Spaghetti Junction," it is part 'whirl,' part 'Y,' part stacked roundabout. Amazingly it actually works quite well since the main movement (M6 to A38(M) and vice-versa) has free-flow slip-roads. 

By far the worst kind of all-motorway junction, predictably, involves the roundabout. Roundabouts should not be used either as a terminating junction or as a stack in a motorway-to-motorway interchange...but they are, all too frequently. Probably the worst one is the M60/M62/M66 N of Manchester where all the through traffic on the M60 is funnelled onto the roundabout. Other offending stacks include the A1(M)/M18 S of Doncaster, the A1(M)/M25 N of London and the M61/M65 W of Blackburn. Some of the worst ones, like the M1/M62 S of Leeds and the M20/M25 E of London, had partial free-flow roads tunnelled under existing junctions at vast expense. Other offending termination roundabouts include the M4/M32 N of Bristol, the M57/M58/A59/A5036 N of Liverpool (probably the worst) and the M60/M67/A57 E of Manchester. Motorway terminations should use the Y-junction or a simple fork like the M8/M80 in Glasgow.

That pretty much covers the all-motorway interchanges found in Britain. For more information you should check out CBRD or SABRE, both of which are far more comprehensive and knowledgeable than me.


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## ChrisZwolle (May 7, 2006)

jandeczentar said:


> Mercifully we don't have a lot of cloverleaf junctions in the UK. As far as I know there are only 2 in Britain: 1 in Livingston, 1 in Redditch and neither on a motorway. The weaving between incoming and outgoing traffic is dangerous, especially at peak periods.


It helps a lot if there are separate distributor/collector lanes, which should be standard at most high-trafficked cloverleafs in my opinion.


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## jandeczentar (Aug 14, 2009)

ChrisZwolle said:


> It helps a lot if there are separate distributor/collector lanes, which should be standard at most high-trafficked cloverleafs in my opinion.


Even with parallel collector/distributor roads the essential problem of the cloverleaf remains. There will still be vehicles trying to move out from the slip road at the same moment as other vehicles are trying to move in onto it, leading to side-on collisions. Also, in the example you gave, the slip roads running parallel to the distributor lanes through the underpass are only about 185m long. That's pretty short, even at relatively low speed. Is that standard or is this an unusually small example?

I know why there are so many (cheapness) but even so, I'm amazed they're so prevalent in Europe given their obvious limitations. I don't know what the accident rate is on junctions like this but I can't imagine they're that safe, especially in heavy traffic and even with the collector/distributor lanes.


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## Tom 958 (Apr 24, 2007)

jandeczentar said:


> Even with parallel collector/distributor roads the essential problem of the cloverleaf remains. There will still be vehicles trying to move out from the slip road at the same moment as other vehicles are trying to move in onto it, leading to side-on collisions. Also, in the example you gave, the slip roads running parallel to the distributor lanes through the underpass are only about 185m long. That's pretty short, even at relatively low speed. Is that standard or is this an unusually small example?
> 
> I know why there are so many (cheapness) but even so, I'm amazed they're so prevalent in Europe given their obvious limitations. I don't know what the accident rate is on junctions like this but I can't imagine they're that safe, especially in heavy traffic and even with the collector/distributor lanes.


I think that their saving grace is that on a simple cloverleaf with CD's, everybody in the left lane of the CD wants to exit to the right, and everyone entering from the right wants to be on the left, so there's a strong incentive for drivers to cooperate with each other. The CD removes through vehicles from the equation, the drivers of which may be inattentive or indifferent to the needs of merging and exiting drivers. It also gives drivers entering the motorway from the CD a much longer ramp on which to increase their speeds to match those on the motorway before attempting to merge. The same is true in reverse for exiting traffic.


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## Uppsala (Feb 26, 2010)

kalle_sg said:


> Interchanges with roundabouts occur in Sweden - especially in urban areas and on the newly constructed roads. Like this, E4 around Uppsala:
> 
> 
> 
> ...


I don't think we have one standard here in Sweden. They are built in different times and they don't looks like they are so interested how they made one construction in another part of Sweden. They just building one construction which are quite good just for the place its built and looks quite good at the times its built. Sometimes I think they are more interested about constructions from other countries than other parts of Sweden.

So here in Uppsala we have lot of roundabouts but in the rest of Sweden there is not so many of them at the motorways. There is more diamonds and trumpets. There is a few cloverleaf's too. One of them is near the bridge over Öresund.


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## Nexis (Aug 7, 2007)

I like Roundabout Interchanges we have a few in NJ, i also like Trumpets and Parcos.

US 202 @ US 206 / NJ 27









Its controlled by Traffic Lights on the Busy ramps and yields on the none busy ramps. I could not find any other good NJ Roundabout Interchange pictureshno:


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## Penn's Woods (Apr 8, 2010)

Nexis said:


> I like Roundabout Interchanges we have a few in NJ, i also like Trumpets and Parcos.
> 
> US 202 @ US 206 / NJ 27
> 
> ...


I passed through there just last weekend! I can remember it before that overpass was built.
There must be Google images of circles like Flemington.... (Which is still a "pure" traffic circle with no overpass.)


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## Nexis (Aug 7, 2007)

Penn's Woods said:


> I passed through there just last weekend! I can remember it before that overpass was built.
> There must be Google images of circles like Flemington.... (Which is still a "pure" traffic circle with no overpass.)


I believe the NJ DOT is upgrading a few South Jersey Circles to to Roundabout Interchanges.


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## 3naranze (Nov 10, 2009)

unicum in italy and maybe in the rest of the world:
A23-A4 junction near Palmanova (UDINE). You merge at high speed
(I don't remember if there's a speed limit) and if you have to reach Udine(north) from Venice(east), 
the exit is on the left. It became the brand of the Autovie venete,
motorway concessionaire.








Horseshoe junction at catania by-pass and the new motorway catania-siracusa:
















opening soon (this june):
the new trumpet junction A27-A28 at Conegliano:


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## Paddington (Mar 30, 2006)

Not an expressway, but here is a new type of "super street" intersection they are building in Ohio at State Route 4 to connect a busy major road with a minor one:















Generic Super Street:


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## Paddington (Mar 30, 2006)

This type of intersection, called the "Michigan Turn" is extremely popular in the Detroit area, especially on major thoroughfares such as Ford Road, Woodward Ave., Michigan Ave., Telegraph Road:
























Interactive animation


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## NCT (Aug 14, 2009)

Must say the Mitchigan turn is quite clever - does require a very wide central reservation though.


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## Paddington (Mar 30, 2006)

The Detroit area is essentially unsurmountable by foot. The only place that might be worse for pedestrians that I've been to is Texas, because of its expressway + service road setup. 

In nearby Ohio, you can kind of get around by foot a little bit in the suburban areas. In Michigan, I've noticed that most roads don't even bother building pavements for pedestrians. The type of urban layout preferred by the DOT in Michigan is huge boulevards with big central medians for the U-turns. A 6 lane road now becomes as a wide as a 10 lane road. There aren't a whole lot of stops and you can blaze by easily at 60-70 mph (well above the speed limit) on Ford Road or Michigan Ave. where I live.


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## Bartolo (Sep 20, 2004)

The way roads are set up in the Detroit area are way different than they are in the Toronto area, or anywhere else I've been for that matter. Hall Road which is basically the only mile road I've been on is basically an expressway with driveways. The speed limit is 50 and when I was driving on it I was doing more like 60-70. Where I live there is nothing like it. The suburbs for the most part in my area are walkable to a certain degree.

Also to a person that is not from Michigan, the Michigan Left can be a little hard to grapple at first. I know it took a little while for me to get used to it. I do see its advantages, but the a major issue is they do require quite a large ROW, and that it forces to have back lotting, or the use of frontage roads, seeing as you cant really have non-signalized intersections with those kinds of roads. 

In Michigan do they use stack interchanges? I can't remember if any of the ones I would of gone through were. As Southern Ontario and Michigan have similar climates I just wonder if they do use them. Here there is only Stack and that is the 400-407 interchange.


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## Paddington (Mar 30, 2006)

The roads in Michigan are complicated. My family is in Toledo so I've been coming to Detroit for many years. I had a hard time with driving here until I actually moved here. Even now though, I've almost gotten into an accident a few times because here almost every intersection is different. There's some places where you make a left turn directly. There's some places where you make a Michigan Turn. Then there's other places where you turn left on to the median, and then you face a blinking red light and try to dodge the traffic coming from the right. It can be very confusing.

By contrast, in nearby Ohio, every intersection is pretty much the same. They all meet at right angles. They usually have dedicated left turn lanes. That's all there is to it. U-turns are infrequent, if not banned outright. Ohio doesn't have any metros as big as Detroit, but Columbus has pretty big roads in some places. Somehow Ohio gets things done quite well while keeping the roads real simple at the same time. 

Detroit does have a couple of 4 level stack interchanges. There's I-96/M-39 (Southfield Fwy) pictured below, I-75/I-696, and possibly I-94/I-96 (asymmetric).










Detroit's year round temp is 49, while it's 47 for Toronto. There is about 45 inches of snow here.


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## Bartolo (Sep 20, 2004)

They do, do things differently in Michigan. It is kind of expected though in a way that the car is king there. The car industry is huge in Michigan. In Ontario pretty much all intersections are 90 degree right angle, and I have never come across a Michigan left style intersection. Most major intersections have left turn lanes, usually with dedicated left turn phases.


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## BWG95 (Jul 20, 2010)

kalle_sg said:


> Interchanges with roundabouts occur in Sweden - especially in urban areas and on the newly constructed roads. Like this, E4 around Uppsala:
> 
> 
> 
> ...


Well, there are a number of motorways interchanges in sweden, although they aren't many. In malmö. we have two cloverleaf interchanges, two half cloverleaf, half stack interchanges, one half stack interchange and one full stack interchange. In Helsingborg, there are two, both are wuite unique, a mix of different types of interchanges. In Gothenburg, there is one half stack interchange, one very unique (and not so very good) interchange at the e6/e20 crossing, and also a stack interchange. Stockholm has two stack interchanges on the e4/e20 motorway, and one on the södra länken tunnel. There's also a half stack interchange in the capital.

Besides from that, there are smaller ones in cities like Linköping and Uppsala, and the connection to Stockholm's international airport Arlanda, all three from the E4 motorway.


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## BWG95 (Jul 20, 2010)

So we have quite a few motorway interchanges in Sweden as well!


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## setiajie (Sep 30, 2009)

*Surabaya - Mojokerto Tollway (East Java - Indonesia)*

This is the begin of Surabaya - Mojokerto Tollway at Waru Interchange :


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## Norsko (Feb 22, 2007)

Could someone please explain the purpose of that Italian horse shoe junction? I do not understand it :dunno:


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## ChrisZwolle (May 7, 2006)

^^ It's easy. If two roads meet under a very limited angle, you cannot construct a reasonable curve on that specific location. A curve with a larger radius can be constructed just downstream to ensure a reasonable flow. 30 km/h curves on a motorway cannot be considered a reasonable or safe flow.


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## Norsko (Feb 22, 2007)

Thanks! Then I understand


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## Troopchina (Oct 7, 2005)

That horseshoe junction is really weird. 

But since it is in Italy it doesn't surprise me, traffic patterns there, particularly in cities strike me as very odd.


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## Verso (Jun 5, 2006)

Why is that horseshoe junction so far from the actual physical meeting of the motorways? Why not like H3×A2 in Slovenia or M70×M7 in Hungary?


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