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General Category => General Discussion => Topic started by: pehayes on February 26, 2018, 12:57:59 PM

Title: Traffic Flow
Post by: pehayes on February 26, 2018, 12:57:59 PM

Diverging Diamond.
Newspaper today had an article about the concept of a "Diverging Diamond" highway interchange.  Several years ago I confronted one of these intersections in Joplin, Missouri while running a Route-66 tour.  First impression was that the traffic engineers were on LSD when they drew it up!  Today's newspaper says the design is growing in fame and now there are more than 40 across the country.  I've attached a satellite view of the Joplin interchange and a short YouTube video animation to show you how it works.  I especially like that it safely includes bicycles and pedestrians in the mix.


(http://thumb.ibb.co/fLj2Xc/joplin.jpg) (http://ibb.co/fLj2Xc)


https://www.youtube.com/watch?v=HD-0QnUlLOQ


Patrick Hayes
Fremont CA

Title: Re: Traffic Flow
Post by: screamday on February 26, 2018, 01:37:49 PM

Should be an interesting mix with cell phone users and some of the other technology distractions drivers have in their cars today.

Title: Re: Traffic Flow
Post by: smdl on February 26, 2018, 01:48:42 PM

Here's a good overview from WSDOT:

https://www.youtube.com/watch?v=5gLxlXamhgY (https://www.youtube.com/watch?v=5gLxlXamhgY)

I haven't experienced one of these yet, but will withhold judgement until I give it a fair go.  Similar to roundabouts, it will certainly take drivers some time to acclimate!

Cheers,
Shaun

Title: Re: Traffic Flow
Post by: twowings on February 26, 2018, 01:53:17 PM

Am I seeing correctly? It looks like there are two criss-cross sections of the north-south highway?

Just like my old Aurora "Model Motoring" HO slot-car set!  That was fun but... :shocked:

Title: Re: Traffic Flow
Post by: KiwiKev on February 26, 2018, 02:20:59 PM

Holey Moley - looks like a formula for disaster to me. Dreamed up by some crack pot university graduate dare I say it ?


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Title: Re: Traffic Flow
Post by: Carlo DeSantis on February 26, 2018, 02:55:43 PM

There have been several pf these intersections installed as part of the I-90 Tollroad rebuild in Illinois.

Additionally, there is one going into a local intersection in my area.

They do move a lot of traffic, but it takes a while for the traffic control lights to cycle through all of the positions.  Jury's out in my mind.

Best,

Carlo

Title: Re: Traffic Flow
Post by: Guzzi Gal on February 26, 2018, 03:02:55 PM

 :shocked:

Title: Re: Traffic Flow
Post by: oldbike54 on February 26, 2018, 03:32:09 PM

 While I do like the pedestrian and bicycle lanes , wouldn't it be easier to just build a large roundabout with elevated pedestrian and bike lanes ?

 Dusty

Title: Re: Traffic Flow
Post by: rocker59 on February 26, 2018, 03:42:25 PM

I-44 Exit 77 in Springfield Missouri has this.  Works great, in my experience.

I exit here, needing to turn left, North on Hwy 13.  With this "double diamond" crossover, there is no waiting to turn left.

Love it!

Title: Re: Traffic Flow
Post by: pehayes on February 26, 2018, 04:23:39 PM

I wonder what happens when you get a light snow and it covers the lane lines???!!!!

Patrick Hayes
Fremont CA

Title: Re: Traffic Flow
Post by: Devildog on February 26, 2018, 04:33:40 PM

It's a brilliant design, at least in concept. I picture confused elderly drivers bringing traffic to a standstill.

Title: Re: Traffic Flow
Post by: stormshearon on February 26, 2018, 04:34:05 PM

Sheesh - considering how well Washingtonians currently handle roundabouts (treat them like stopabouts) this DDI thing should work really, really well. /sarc

Title: Re: Traffic Flow
Post by: travelingbyguzzi on February 26, 2018, 04:57:55 PM

I have seen one on aerial photos under I-15 near St. George Utah. I keep meaning to plot a trip thru there just for the experience, but now that I know of the one near Joplin.....

Title: Re: Traffic Flow
Post by: jwinwi on February 26, 2018, 05:05:04 PM

Brilliant engineering when most drivers in my home town have no idea how deal with a roundabout :violent1:
Pat: Thanks for the warning!

Title: Re: Traffic Flow
Post by: RinkRat II on February 26, 2018, 05:17:18 PM

Quote from: travelingbyguzzi on February 26, 2018, 04:57:55 PM

I have seen one on aerial photos under I-15 near St. George Utah. I keep meaning to plot a trip thru there just for the experience, but now that I know of the one near Joplin.....

      It's actually more of a triangle because you can't continue eastbound, but it works great as now traffic flows better as you are dealing with I-15, A shopping center and a major North/ South  surface street. Much better than the interchange they had before.  IMHO

         Paul B :boozing:

Title: Re: Traffic Flow
Post by: rss29 on February 26, 2018, 06:18:22 PM

I drive through one of these twice a day. When it first opened about two years ago it seemed odd, but now is just normal. It’s not at all confusing at ground level. I think they help with traffic flow. They transformed that intersection’s gridlock into something slightly less congested than gridlock since it lengthened the effective turning lanes.

Title: Re: Traffic Flow
Post by: nc43bsa on February 27, 2018, 12:56:41 AM

I know of three of these within a 30 minute drive of my house.

Believe me, it's a lot clearer in person than it is in the aerial drawings and animations I've seen.

Once you've been through it once, it makes a lot of sense, especially with intersections of heavily traveled surface streets and expressways.