A new kind of interchange eliminates left turns.

http://www.slate.com/id/2300425/

by brianmckenzie • 15 years ago

59 23 15 years ago

"New" ?? This was discussed 410 days ago:: http://news.ycombinator.com/item?id=1437430

Also just recently re-submitted: http://news.ycombinator.com/item?id=2833446

In particular, here's the WikiPedia article about the design: http://en.wikipedia.org/wiki/Diverging_diamond_interchange

gojomo• 15 years ago

New to most people; I haven't driven through one yet. And on the timescales of road engineering, pretty much anything novel in the past 20 years that's not yet widespread is still 'new'.

Semiapies• 15 years ago

Also, the "new" is in the headline.

chadgeidel2• 15 years ago

I live in a town of spectacularly bad drivers so I may be jaded, but I just can't believe folks will "figure this out". People where I live have a hard enough time figuring out what lane they should be in on a straight two lane road let alone merging, signalling, stopping at intersections, one-lane roundabouts, etc.

treeface3• 15 years ago

You might think so, but everyone says this everywhere in the world. For example, this is the top argument that people use against the implementation of the generally-safer, higher-throughput modern roundabouts. Without fail, every time a modern roundabout is installed, the exact same thing happens: congestion is eased, the incidence of fatal accidents falls some 90%, and a multitude of people say things like "well, I just couldn't believe that these people where I live were smart enough to handle it, but it worked!"

What people usually attribute to bad driving is usually the fault of poor traffic planning. Humans tend to be the same, circumstances change.

asmithmd1• 15 years ago

Massachusetts has the worst drivers in the the country - that is a fact - MA has the highest accident rate in the US. I blame the roads. Every intersection in MA is unique - there are no idioms. Take a look at these two intersections with 4 lane roads that were recently "fixed"

Just keep moving or you will be stuck for hours: http://maps.google.com/?ll=42.361501,-71.070455&spn=0.00...

Something for everyone: overpass, circle, and jug handles:

http://maps.google.com/?ll=42.24915,-71.171166&spn=0.002...

chadgeidel2• 15 years ago

(sorry for replying so late - I just remembered this comment)

I wholeheartedly agree that we should increase driving standards, and better traffic engineering is the first step. I was just commenting on the fact that most people I talk to don't want to learn how to make their morning commute safer and more efficient.

psadauskas• 15 years ago

They have something similar near the town I grew up: http://maps.google.com/maps?q=columbus,+in+&hl=en&ll...

It was terrible the first few years. Nobody could ever figure out which lane they were supposed to be in, and ended up driving on the wrong side of the crossed-over section. Granted, the people here are still having trouble figuring out roundabouts, but I found this very confusing my first couple times through the intersection.

m0nastic• 15 years ago

I didn't get very much sleep last night, but it seems like a more complicated solution than just using "jug handles".

matwood• 15 years ago

I'm glad someone brought this up. I think it's NJ that has a lot of jug handles and they do a pretty good job at eliminating all left hand turns and once I understood the term they were easy to use. I also think they would be easier to implement on existing roads.

juiceandjuice• 15 years ago

They started putting in lots of continuous flow intersections in Utah: http://en.wikipedia.org/wiki/Continuous-flow_intersection

vyrotek• 15 years ago

The new Pioneer Crossing intersection is great. I drive through it every day.

Here's a video describing the flow: http://www.youtube.com/watch?v=xWHEi8baCPE

oflannabhra• 15 years ago

They're in the process of building one of these here in Lexington, KY. The link the the video simulation was definitely enlightening. We'll see whether drivers will actually be able to pick up how to navigate it.

pedalpete• 15 years ago

isn't each point of cross-over/merging a more likely point of failure?

I could see there being less accidents of the left-turn variety being exchanged for more less-dramatic accidents.

Aren't we better of just using roundabouts? or http://en.wikipedia.org/wiki/Roundabout#Turbo_roundabouts??

digitalstax• 15 years ago

I lived a few blocks from the one in Springfield, MO when it was built. It just doesn't feel right at first. But I haven't heard of any problems and it seems to serve its purpose.

protomyth• 15 years ago

I cannot help but think this thing will be a nightmare in the snow. It just has a slide into the wrong place vibe.

savrajsingh• 15 years ago

You mean a roundabout?

murz• 15 years ago

Reminds me of Michigan left.

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

Bo102010• 15 years ago

There is one of these 300 meters from my apartment.

It's not very confusing exiting the highway and turning left - just follow the lights.

It is kind of confusing exiting the highway and turning right. Right-on-red is allowed, and to make such a maneuver you have to look in strange places for traffic that might hit you. I've almost messed it up a few times. The other option is to let people honk at you while you wait for a green.

I'm curious as to what will happen when the power to the lights fails.

A new kind of interchange eliminates left turns.

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