I spotted this unusual design for a new diverging diamond interchange at the US 50 / Route 291 interchange in Lee's Summit.
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FU8uTyDA.jpg&hash=7854905655ccbfe382b9bbd5755adfa000e0bbbb)
http://www.modot.org/kansascity/major_projects/Route_50_291_Interchange.htm
I am concerned about the upper-most signal being too close to the roundabout. Traffic backing up into the roundabout is not a good thing.
Quote from: Big John on May 06, 2015, 03:34:08 PM
I am concerned about the upper-most signal being too close to the roundabout. Traffic backing up into the roundabout is not a good thing.
And why would the signal even be needed? It's a merge. A yield sign would be more appropriate.
Shoot, with a second roundabout similar to the top one, all signals could be eliminated from this interchange. Think about it,
the first DDI with no signals, and the only potential collisions would be sideswipes.
They're doing something similar at I-49 and 155th Street
http://www.modot.org/kansascity/major_projects/I-49_155th_Interchange.htm
This hurts my brain.
Quote from: Brandon on May 07, 2015, 03:42:32 PM
Quote from: Big John on May 06, 2015, 03:34:08 PM
I am concerned about the upper-most signal being too close to the roundabout. Traffic backing up into the roundabout is not a good thing.
And why would the signal even be needed? It's a merge. A yield sign would be more appropriate.
Shoot, with a second roundabout similar to the top one, all signals could be eliminated from this interchange. Think about it, the first DDI with no signals, and the only potential collisions would be sideswipes.
That occurred to me, too, though...
This design appears to be very site specific (https://www.google.com/maps/place/Lee's+Summit,+MO/@38.9315648,-94.378559,13z/data=!4m2!3m1!1s0x87c0dff6a8b596fd:0x8d2c2e9a007b187) as opposed to being prototypical because of the unusual distribution of traffic flows: very heavy between MO 291 south and US 50 in both directions, much lighter (and with little likelihood of growth) to the north. I assume that's why that northernmost signal is there instead of a yield or merge.
The scheme for I-49 at 155th (http://www.modot.org/kansascity/major_projects/documents/_J4P2256_Public_Hearing_0917_zoomed.pdf) looks more prototypical to me-- just mirror the east side to the west. However, doing that would entail putting all the through traffic for the arterial on the same short segment of the roundabouts, something that wouldn't happen if the arterial roadways didn't do the DDI swap.
FWIW:
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FXOWrJlf.jpg&hash=0e5d86eeb1f7cc15838f09833023461d9aa53de6)
I hereby trademark the term "Diverging Death Roundabout".
This seems like something that should be built with a standard roundabout on the east, and a teardrop on the west. Adding the crossover is just confusing.
This is an interesting solution to the problem of two-way frontage roads. Personally, my inclination was that they should be converted to one-way frontage roads along US 50 in Lee's Summit, but I can see merit to MoDOT's approach here.
I found some drone videos on YouTube (6 by that same user)
(note there is a similar thread on the "national board" https://www.aaroads.com/forum/index.php?topic=15496.25)
Bizarre. The demolition of the pre-existing overpass and proposed construction of the two skewed overpasses is going to be the bulk of the costs. Would find a way to preserve the pre-existing overpass. Am assuming here it is neither fracture critical or functionally or structurally obsolete. A example of governmental over-reach, i.e. waste.
Quote from: DJStephens on September 21, 2018, 04:06:13 PMBizarre. The demolition of the pre-existing overpass and proposed construction of the two skewed overpasses is going to be the bulk of the costs. Would find a way to preserve the pre-existing overpass. Am assuming here it is neither fracture critical or functionally or structurally obsolete. A example of governmental over-reach, i.e. waste.
There are two US 50/SR 291 interchanges owing to a dogleg overlap, with the SR 291 connections flying over US 50 in both cases. I suspect all of the overpasses classify as functionally obsolete because they do not have sidewalks and have no room to add any, which is a very common problem with bridges at urban freeway service interchanges in Missouri.
And before you ask why anyone would want to walk along a sidewalk on a freeway bridge: in many cases there is a motel on one side of the freeway and a breakfast joint on the other. It is a benefit not to have to start the car up and drive less than a quarter-mile just to get across the freeway without having to sidle along a one-foot-wide strip between the shoulder stripe (if one is even provided) and the crash barrier.
A walkway bridge could simply be constructed alongside the existing no walkway bridge, also.
That single lane off ramp, that cuts a significant chunk out of that shopping malls' parking, that certainly will be a problem. Does Pete Rahn have something to do with this?? As an outside consultant? I'd go back to the drawing board.
I've driven through this monstrosity a few times. It's a confusing mess.
I have to say that MoDOT is good at putting "out there" ideas to the test. Wasn't the first SPUI in MO?
And MoDOT is usually pretty good with signage, but anybody from out of the area that has to drive through that is going to have a very hard time.
I know it's development-based, but I hate frontage roads on Interstates (looking at you, Texas).
Quote from: M86 on September 24, 2018, 12:57:03 AM
I have to say that MoDOT is good at putting "out there" ideas to the test. Wasn't the first SPUI in MO?
And MoDOT is usually pretty good with signage, but anybody from out of the area that has to drive through that is going to have a very hard time.
I know it's development-based, but I hate frontage roads on Interstates (looking at you, Texas).
And DDI.