Diverging Diamond Interchange at Front Street & I-435

[Some_Guy]

The city of Liberty/MoDOT just finished that interchange not too long ago.  I doubt they would want to revisit anytime soon.  Although, that idea does have merit but may not be practical for some time due to shortages in funding sources.

[enough]

i just experienced this interchange on foot. ddi interchanges are not pedestrian friendly.

admittedly there aren't many peds at i-435 and front street, but it's nearly a quarter mile of very hostile environment for anybody wanting to walk along front. 500 feet or more of that quarter mile is in the middle of the street with traffic going past on both sides, and about 150 feet of it is in a concrete chute 62 inches wide and with 48-inch walls on both sides.

take care not to fall. nobody will ever find you.

[AlbertHammond]

Last night KDOT held an info meeting on the upcoming diverging diamond at Roe & I-435. I travel this intersection almost daily and often during the peak of rush hour and I never found it to be a traffic nightmare. But…I guess they feel that it needs replaced, so they need to go full-blown fancy with a DD. ……Progress.

http://www.ksdot.org/kcMetro/pdf/KDOT%2 ... roject.pdf

https://www.ksdot.org/kcmetro/pdf/Final ... er2012.pdf

[Volker Dad]

Last night KDOT held an info meeting on the upcoming diverging diamond at Roe & I-435. I travel this intersection almost daily and often during the peak of rush hour and I never found it to be a traffic nightmare. But…I guess they feel that it needs replaced, so they need to go full-blown fancy with a DD. ……Progress.

http://www.ksdot.org/kcMetro/pdf/KDOT%2 ... roject.pdf

https://www.ksdot.org/kcmetro/pdf/Final ... er2012.pdf

If they should do anything at all (big if), I'd say put a roundabout where each of the lights are in that diagram.

[smh]

When these interchanges were first developed I thought they were a nifty innovation in moving cars. I now realize that while that may be the case, they are nightmares for pedestrians. I suppose there aren't any pedestrians on Roe anyway, but this interchange will guarantee it remains that way.

[shinatoo]

A nightmare made worse by a roundabout. Like the one proposed for 291 south and US 50 in Lee's Summit.

[flyingember]

Post subject: Re: Diverging Diamond Interchange at Front Street & I-435
When these interchanges were first developed I thought they were a nifty innovation in moving cars. I now realize that while that may be the case, they are nightmares for pedestrians. I suppose there aren't any pedestrians on Roe anyway, but this interchange will guarantee it remains that way.

that's modot for you. and the fix seems simple.

if you're on the right of traffic going northbound, when northbound traffic can get through the intersection it's actually leaving the perfect path right across southbound traffic to the middle of the intersection. you just cross anyone turning right onto the highway, and these people already yield for pedestrians today. then repeat going back to the same side of the road or you can use the other half of the cycle and change sides of the road. suddenly two pedestrian cycles becomes one and is actually shared with the car cycle. it would mean you always have a pedestrian go light no matter what, the ultimate setup. and to cross to the other side you don't need to slow traffic down, you just shift the best crossing spot to the intersection instead of a few blocks over at their destination.

seems like a DDI is more pedestrian friendly if modot would do it right

they just need to put a dedicated pedestrian path down the middle between the two lights. by sharing it with both directions you need less space to put one in.

If they should do anything at all (big if), I'd say put a roundabout where each of the lights are in that diagram.

a roundabout could easily hinder traffic more than even what's there today.

obviously they're perfect to replace stop signs and street lights in a light traffic environment. a roundabout means more cars can get through without stopping. there's plenty of cases where they make sense to do.

but picture what will happen if you have 30 cars show up at once from any of the four directions and all wanting to go any of the 10 different possible paths.

imagine a timid driver going onto the far onramp makes it through the first roundabout but then has problems getting a gap through the second one

while they're timidly waiting imagine if another 15 cars show up from different directions. than another 8. and another 10, etc.

if it were a single roundabout you can see everything at once and get a hole. traffic blocking one entrance doesn't block any other entrance from going to their destination. with two you have all the traffic from three sources blocked if the wrong place gets stuck.

and this has a ripple effect backwards. with a street light the driver has clear paths for all 10 possible paths.

over the current lights a DDI halves the number to to go through to get on/off the highway. and that's a huge improvement over what's there today.

current-
you have one light cycle to let all traffic getting off to get onto the bridge. you can't have both ways go past the bridge at the same time so the quickest is to get off and wait at the other light
you have another cycle to let traffic coming from town turn left onto the highway.
you have a thru option where the getting the highway turning left group continues on too.

you can share two of these one direction. like you can do off and on for northbound and then off and on for southbound as two cycles. you can share thru and on the same respectfully. it just doesn't cut a cycle, is just another option.

so to get all paths covered you go through four patterns in the light cycle and it's possible a ton of cars will need to sit through greater than one cycle if the timing is off for the traffic (like you get through light one but too many cars means you have to wait a cycle to turn left onto the highway

a DDI takes it down to 2. you have one light to cross traffic inbound to get under the highway and another to cross thru traffic outbound past the highway. people getting on the highway have one light to get thru, best case. if you're getting off you never wait for a light, only a gap in traffic, just like a roundabout. if you're getting on you go thru the light and worry about traffic from no other direction than what's in front of you and who else is getting on the ramp, and the latter is exactly like today.

[shinatoo]

The one in Springfield has the pedestrian path down the middle. I assumed they were all this way.

[smh]

The one in Springfield has the pedestrian path down the middle. I assumed they were all this way.

I believe they are all that way. I have to respectfully disagree with our friend that this is good for pedestrians. It puts you those on foot in the middle of four lanes of traffic. Mildly unpleasant to say the least.

[shinatoo]

The one in Springfield has the pedestrian path down the middle. I assumed they were all this way.

I believe they are all that way. I have to respectfully disagree with our friend that this is good for pedestrians. It puts you those on foot in the middle of four lanes of traffic. Mildly unpleasant to say the least.

As opposed to two lanes of traffic and a 20 foot drop on to 8 lanes of traffic?

[smh]

The one in Springfield has the pedestrian path down the middle. I assumed they were all this way.

I believe they are all that way. I have to respectfully disagree with our friend that this is good for pedestrians. It puts you those on foot in the middle of four lanes of traffic. Mildly unpleasant to say the least.

As opposed to two lanes of traffic and a 20 foot drop on to 8 lanes of traffic?

Also not great. But with something other than a chain link fence, the typical sidewalk on an over pass becomes a lot more pleasant.