In the city of Nogales, Sonora, Mexico they have this kind of lanes configuration where you have to drive on the right lanes to make a left or U turn. This was arranged like that because the median is very narrow and it was difficult for large trucks to make U turns.

Is there any avenue with this kind of lanes arrangement in your city?

http://i41.tinypic.com/23vcmk1.jpg

http://i41.tinypic.com/50nsqc.jpg

I find this arrangment very dumb and unsafe, I am wondering which monkey made this out of his head, because he didn´t have the brain to think that some drivers which don´t see or accidently start driving on the lanes fro straight direction might crash into the leftturning vehicles or left turning vehicles pass the road when the trafficlight just turned red and other cars allready start driving.

^^ That's interesting :nuts:

And no, we don't have these. When the turn is too narrow, you simply cannot turn or make a U turn.

Well, there are tons of signs indicating the left turn lanes, I don't live in that city but the first time I drove with that new lanes I got the idea quickly and I wasn't confused at all.

However, I don't have the statistics about accidents with that new arrangements.

I even searched on Wikipedia about this and I couldn't find anything. And they do have lots of articles about road configurations.

this is the first time i ever seen something like this...
seems logical and nicely implemented... but then again, really dangerous and there should be warning signs all over the place so the people wouldn't get confused...

There's a ton of these situations in New Jersey. They're called jughandles here in the US.
They're just about standard on roads with more than two lanes, which are everywhere in Jersey.

http://farm4.static.flickr.com/3242/3147816797_0585005de7_o.jpg

Here's one in Pennsylvania- this is the jughandle with the main road just to the left of this pic:

http://farm4.static.flickr.com/3253/3148661556_81cc69dee7_o.jpg

In most of EU U-turns are forbidden or at least discouraged, especially for trucks.

^^ Indeed. One good thing about the roundaboutmania in some countries is you can make U-turns quite easy.

Salt Lake has some really weird turns that were only implemented like a couple years ago, I never got to experience one myself before I moved. I forget what they are called. But they have you drive on the other side of the road if you're going to turn left...or something like that. I'll have to try to remember the name...

Here's one in Utrecht, NL:

http://img244.imageshack.us/img244/8513/majellaknoopdp9.jpg
http://maps.google.nl/maps?f=q&hl=nl&geocode=&q=m+van+nimwegenpad&sll=54.046489,5.19104&sspn=2.257767,4.899902&ie=UTF8&ll=52.094771,5.08559&spn=0.000577,0.001706&t=h&z=20

Found it! Here are the new ones they've put in Salt Lake City:

http://enr.construction.com/images2/2007/09/070921-Crossover.jpg

What do you all think?

Found it! Here are the new ones they've put in Salt Lake City:

http://enr.construction.com/images2/2007/09/070921-Crossover.jpg

What do you all think?

woooooooooooow crazy people men,its very dangerous.

I think that one in Salt Lake City is a continuous flow intersection. It was invented and patented by the Mexican engineer Francisco Mier.

In Mexico it's usually called "vuelta inglesa" (english turn)


http://en.wikipedia.org/wiki/Continuous_flow_intersection

These are everywhere in Melbourne due to trams. They're called "hook turns (http://en.wikipedia.org/wiki/Hook_turn)".

I've never seen any of these in Canada. They are quite counter-intuitive, though it seems that in all cases they have dedicated traffic lights, which makes the risk very small, since it doesn't mean that one has to give way to cars going straight (and the ones coming from the other direction).

I would still probably get confused if I encountered such an intersection without any knowledge of it in advance.

I think it's great! Very useful for intersections with lots of trucks.

To reduce confusion regarding the left-turn lane, the left-turn lane and the straight-through lanes are usually separated by a concrete barrier or traffic island.

If properly isolated, drivers shouldn't really notice they're in a continous flow interchange, all you have to do is follow the directions and obey the traffic light.

That looks dangerous.

why are you all talking about this as dangerous? it is absolutely not more dangerous than ordinary intersection with traffic lights. the only problem is this what TheCat has said - they are counter intuitive

These are everywhere in Melbourne due to trams. They're called "hook turns (http://en.wikipedia.org/wiki/Hook_turn)".

I was just coming along to post that. :lol:

If you follow the traffic lights, it's not more dangerous than an average intersection.

^^ It's not very common in some places, which might lead to confusion, hence possibly dangerous situations. Road layouts should be standardized as much as possible at all times. People expect situations to be similar.

How about this?

http://images29.fotosik.pl/13/6946cd72884ef879.jpg

This sign is somewhere around the highest tree in the foreground:
http://images23.fotosik.pl/13/27593b9cb0fff4fb.jpg

^^ This would be better and simpler;

http://www.signaco.si/znaki/obvestila/obvest8.jpg
( and then turn left again)

^^ This would be better and simpler;

http://www.signaco.si/znaki/obvestila/obvest8.jpg
( and then turn left again)

we have a lot of these. unfortunately, people are often stupid and don't understand the purpose of that sign, and are forcing to turn direct left.

Found it! Here are the new ones they've put in Salt Lake City:

http://enr.construction.com/images2/2007/09/070921-Crossover.jpg

What do you all think?

i'm not sure, but this was invented in mexico....

an example of 'vuelta inglesa' (english turn)

http://img523.imageshack.us/img523/2640/dibujo2xu1.jpg (http://imageshack.us)
http://img141.imageshack.us/img141/4863/dibujo4jb4.jpg (http://imageshack.us)
http://img141.imageshack.us/img141/4852/dibujo3ib8.jpg (http://imageshack.us)

2,3,9,10 stright
1,4,5,6 left turns
7,8,11,12 to change of line

^^ what is actually the purpose od this? additional trafficlights and slowing down the traffic?

Remember the left turn is the most problematic on many intersections, especially if two flows cross eachother at that left turn.

^^ what is actually the purpose od this? additional trafficlights and slowing down the traffic?

no, it´s faster than simple left turns (like 5 and 6)

look image up

1,2,3,4,11,12 go at same time
9,10,7,8 after
5,6 at end.
and all again...

(i edited the order)

no, it´s faster than simple left turns (like 5 and 6)

look image up

1,2,3,4 go at same time
5,6,7,8 after
9,10,11,12 at end.
and all again...

ok, but anyway 1234 have additional traffic lights at 7 and 8. green wave can solve only half of those if it exists, other half still waits at another traffic lights.

ok sorry, may be I didn't explain you correctly.

when you are on 7 or 8 and get green, you go to 1 or 4 (50 meters), when you arrive to 1 or 4 it change to green (you don´t wait more time) and 7 and 8 change to red, because if you are on 2 or 3 and get green, 11 and 12 change green too (you don´t wait more time).

9 and 10 haven´t any problem they change to green after 1,2,3,4.

you only wait more time if get green on 5 or 6 (simple left turn) because when you arrive to 11 or 12, they are on red (and you have to wait 7 or 8 change to red, and 1,2,3,4,11,12 are green at same time) :lol :D

i hope don´t get you confuse xD

I'll be in SLC this June, will have to try it to see how it works! It doesn't seem like it would save any extra time but it'll be neat to see.

Found it! Here are the new ones they've put in Salt Lake City:

http://enr.construction.com/images2/2007/09/070921-Crossover.jpg

What do you all think?

I think the continuous flow intersection is one of the most brilliant innovations in intersection design ever (although the name is misleading, traffic definitely doesn't flow continuously). If used on all four legs, it can effectively double the capacity of the intersection without using grade separations. At an intersection of two high-volume urban arterials, where it would most likely be used, only two signal cycles are needed instead of the typical four (north-south left turns, north-south through, east-west left turns, east-west through), so there could be double the number of cars traveling through the intersection at any one time. It's also logical for drivers (unlike a New Jersey jughandle) because all turns are made from the expected lanes (left from left, right from right) just like a normal intersection. The only drawbacks I see are that the right-of-way may need to be a little wider, and access to any businesses located on the corners is more difficult.

The Utah Dept. of Transportation has a website that explains the "CFI."

http://www.dot.utah.gov/main/f?p=100:pg:4156810128996814:::1:T,V:2008,

It also has an excellent animation that shows how it works better than I could ever describe in words:

http://www.udot.utah.gov/i/udot/ucon/cfi_anim.swf

Since this is my first post here, I would like to thank Chris for this wonderful forum, as well as all the posters who make it so interesting. Thanks!!

wow, this is a really cool animation! Thanks for posting! I was extremely amazed. Well, it might be a bit oversized for European suburban intersections and the waiting times for pedestrians to cross the street when left turners AND drivers going straight have green signals should be quite long but anyway, an interesting and creative way of handling high vehicle volumes at at-grade intersections.

Cool work! :cheers:

Anyhow, the European versions with the left turners on the right forming a "quasi-semi-roundabout" (very frequently used in Spain and France) seem to be a bit more appropriate for more urban intersections regarding urban design issues/ qualities.

The only main problem I can see happening is if more cars want to get into that left turn part on the left, and so they end up blocking half the road.

why are you all talking about this as dangerous? it is absolutely not more dangerous than ordinary intersection with traffic lights.

Imagine the traffic lights being out of duty...

These are everywhere in Melbourne due to trams. They're called "hook turns (http://en.wikipedia.org/wiki/Hook_turn)".

Not quite correct. Hook turns are right turns from left lanes, not left turns from right lanes. :cheers:

They are all found in the CBD (or downtown Melbourne), except for some unpopular ones in South Melbourne.

Australia has a few similar intersections, not relating to trams:

Elwood, Melbourne (left turn from right lane) : http://maps.google.com.au/maps?ie=UTF8&ll=-37.891184,144.990676&spn=0.000955,0.001717&t=k&z=19

Gold Coast Hwy on Main Beach (right turn from left lane). http://maps.google.com.au/maps?ie=UTF8&ll=-27.979802,153.422034&spn=0.001068,0.001717&t=k&z=19

Mark.

These are everywhere in Melbourne due to trams. They're called "hook turns (http://en.wikipedia.org/wiki/Hook_turn)".

Here's a photo of 2 cars in Melbourne waiting on the left side of the intersection to turn right over the tram tracks. You can (barely) see the "right turn from left only" sign overhead.

http://farm2.static.flickr.com/1188/3164563474_224324d1a6.jpg?v=0

Better picture of the hook turn sign.

http://farm4.static.flickr.com/3131/3163393411_4954dc99a8.jpg?v=0

Found it! Here are the new ones they've put in Salt Lake City:

http://enr.construction.com/images2/2007/09/070921-Crossover.jpg

What do you all think?


Yeah, this kind of interseccions are common in many cities around Mexico.
This is an exemple in Tijuana.

http://i79.photobucket.com/albums/j152/nattetimen101/cfi.jpg

Closer look
http://i79.photobucket.com/albums/j152/nattetimen101/cf12.jpg

Not quite correct. Hook turns are right turns from left lanes, not left turns from right lanes. :cheers:

They are all found in the CBD (or downtown Melbourne), except for some unpopular ones in South Melbourne.

Australia has a few similar intersections, not relating to trams:

Elwood, Melbourne (left turn from right lane) : http://maps.google.com.au/maps?ie=UTF8&ll=-37.891184,144.990676&spn=0.000955,0.001717&t=k&z=19

Gold Coast Hwy on Main Beach (right turn from left lane). http://maps.google.com.au/maps?ie=UTF8&ll=-27.979802,153.422034&spn=0.001068,0.001717&t=k&z=19

Mark.

The only reason that the thread talks about left turn from right lanes is that most countries drive on the other side of the road to Australia, thus the principle of right turn from left lanes is the same as left turns from right lanes in the rest of the world where people drive on the right. ;)

The continuous flow intersection is an interesting concept. I imagine it could be done here in Melbourne one day.

What's the justification of last few cars driving through intersection to stop at second pair of light for oncoming left turn traffic - why not let all cars through?

The animated video helped me to understand purpose of the idea. At first I was also asking what was the point of it.