4 ms·

The article doesn't mention the numerous downsides to pedestrians for diverging diamond interchanges. Four crossing points means a lot more conflict points and

The article doesn't mention the numerous downsides to pedestrians for diverging diamond interchanges. Four crossing points means a lot more conflict points and a lot more chances for death.

bongodongobob 2y ago
Yeah, that's why it's illegal to walk on the side of highways.
- PaulDavisThe1st 2y ago
  We have an intersection like this just south of Santa Fe, where NM14 intersects I25. NM14 is not a highway.
- ipqk 2y ago
  But you may want to walk across the highway which is almost always allowed.
- whoopdedo 2y ago
  Making walking illegal is how you create the car-first culture that we now know the downsides of.
  - bigstrat2003 2y ago
    Not everyone agrees that car-first design is a problem.
    - ravetcofx 2y ago
      Not everyone who smokes cigarettes agrees that they are a problem
    - EricE 2y ago
      Amen!
  - IncreasePosts 2y ago
    Even without car first culture, you're going to have big roadways meeting at some points, and it doesn't seem particularly smart to have pedestrians mixed in with that.
- aidenn0 2y ago
  It's completely legal to walk on the side of one of these two highways (US-15, a.k.a James Madison Highway) there's even an asphalt MUP for just such a purpose.
howenterprisey 2y ago
Wouldn't the crossings themselves be safer because the cars are coming from fewer directions? I'd rather have four crossings, each with only one direction to look in, than two where I have to scan a whole intersection.
notatoad 2y ago
I dunno, they seem better to me (from experience actually walking across [1], not just looking at pictures on the internet) The crossing are controlled, distances are relatively short and the cars are only coming from one direction. It's a couple of crossings to get all the way through, but they're easy crossings. [1] https://maps.app.goo.gl/6SwfTPrnXkUtTyym8?g_st=ic https://maps.app.goo.gl/6SwfTPrnXkUtTyym8?g_st=ic
ipqk 2y ago
But each conflict point is crossing only one direction of traffic, and there are no cars turning left or right into the crosswalks (which is huge cause of pedestrian impacts). So even though there are 4 crosswalks, maybe the aggregate danger is less?
- bobthepanda 2y ago
  It’s just extremely unpleasant as a pedestrian to be in the middle of 55MPH (88km/h) traffic, even if you are separated by concrete barriers, due to all the noise and particulates. Each individual crossing is also wider if you are staying on the same side of the road. In a traditional diamond you’d be crossing one-lane on and off ramps, not half of one of the major roads each time.
edward28 2y ago
Roadguyrob has a video detailing this issue. https://youtube.com/watch?v=xlnz04EZpMQ https://youtube.com/watch?v=xlnz04EZpMQ
- marcinzm 2y ago
  I don't see why this is unique to a divergent diamond as it only applies to non-light controlled points of conflict of which there are at most two in both designs...
Piskvorrr 2y ago
Four crossing points (two with traffic lights, in this case), whereas for a "normal" interchange, you'd get...also four crossing points. diverging diamond: https://www.openstreetmap.org/directions?engine=fossgis_osrm_foot&route=38.81993%2C-77.63737%3B38.81679%2C-77.64198#map=17/38.81836/-77.63967 https://www.openstreetmap.org/directions?engine=fossgis_osrm... cloverleaf: https://www.openstreetmap.org/directions?engine=fossgis_osrm_foot&route=38.74104%2C-77.52235%3B38.74408%2C-77.51356#map=17/38.74261/-77.51798 https://www.openstreetmap.org/directions?engine=fossgis_osrm...
firesteelrain 2y ago
There is one ten mins from me. It is definitely safer for pedestrians and bike riders. It wasn’t built for golf carts (this is Florida) which really chaps people here. But once they got the lights synchronized, the design works really well. There are little to no accidents. We also have two traffic circles that people call murder circles. The main one has high incident of traffic accidents albeit very very minor in terms of damage and almost no injury.
skywhopper 2y ago
There’s actually fewer crossings involved, so safety for pedestrians should improve as well. But notably these interchanges are often in extremely pedestrian-hostile areas anyway, but it seems more likely that a newly constructed interchange will make at least some attempt to accommodate pedestrians, whereas interchanges built 30+ years ago often ignore pedestrian concerns entirely.
aidenn0 2y ago
This specific interchange looks superior to both a traditional diamond and a cloverleaf for pedestrians. All crossing points are controlled by a light (unlike a cloverleaf), and you don't have to worry about cars taking an unprotected left-turn into you: https://www.google.com/maps/@38.8171139,-77.6412514,3a,75y,344.55h,77.81t/data=!3m6!1e1!3m4!1sOgBPt36zM9RFaYeNTw3d9Q!2e0!7i16384!8i8192?hl=en&entry=ttu https://www.google.com/maps/@38.8171139,-77.6412514,3a,75y,3... [edit] The westbound on-ramp crossing appears to not be protected by a light[1], so would be similar to a cloverleaf onramp; still it's "not bad" as far as non-human-scale interchanges go. 1: https://www.google.com/maps/@38.8191922,-77.6383384,3a,75y,278.34h,98.68t/data=!3m6!1e1!3m4!1sHLmf7t9gWjUjWBTylBMprg!2e0!7i16384!8i8192?hl=en&entry=ttu https://www.google.com/maps/@38.8191922,-77.6383384,3a,75y,2...
presentation 2y ago
Anywhere with an intersection this large seems like it is inherently hostile to pedestrians to begin with.
JeremyNT 2y ago
It seems OK as pictured in the article with a dedicated MUP on one side of the formation. There's probably no interchange design for this volume of traffic that will work all that well for pedestrians and cyclists, though.

The article doesn't mention the numerous downsides to pedestrians for diverging diamond interchanges. Four crossing points means a lot more conflict points and a lot more chances for death.

bongodongobob 2y ago

Yeah, that's why it's illegal to walk on the side of highways.

PaulDavisThe1st 2y ago
We have an intersection like this just south of Santa Fe, where NM14 intersects I25. NM14 is not a highway.
ipqk 2y ago
But you may want to walk across the highway which is almost always allowed.
whoopdedo 2y ago
Making walking illegal is how you create the car-first culture that we now know the downsides of.
- bigstrat2003 2y ago
  Not everyone agrees that car-first design is a problem.
  - ravetcofx 2y ago
    Not everyone who smokes cigarettes agrees that they are a problem
  - EricE 2y ago
    Amen!
- IncreasePosts 2y ago
  Even without car first culture, you're going to have big roadways meeting at some points, and it doesn't seem particularly smart to have pedestrians mixed in with that.
aidenn0 2y ago
It's completely legal to walk on the side of one of these two highways (US-15, a.k.a James Madison Highway) there's even an asphalt MUP for just such a purpose.

howenterprisey 2y ago

Wouldn't the crossings themselves be safer because the cars are coming from fewer directions? I'd rather have four crossings, each with only one direction to look in, than two where I have to scan a whole intersection.

notatoad 2y ago

I dunno, they seem better to me (from experience actually walking across [1], not just looking at pictures on the internet) The crossing are controlled, distances are relatively short and the cars are only coming from one direction. It's a couple of crossings to get all the way through, but they're easy crossings. [1] https://maps.app.goo.gl/6SwfTPrnXkUtTyym8?g_st=ic https://maps.app.goo.gl/6SwfTPrnXkUtTyym8?g_st=ic

ipqk 2y ago

But each conflict point is crossing only one direction of traffic, and there are no cars turning left or right into the crosswalks (which is huge cause of pedestrian impacts). So even though there are 4 crosswalks, maybe the aggregate danger is less?

bobthepanda 2y ago
It’s just extremely unpleasant as a pedestrian to be in the middle of 55MPH (88km/h) traffic, even if you are separated by concrete barriers, due to all the noise and particulates. Each individual crossing is also wider if you are staying on the same side of the road. In a traditional diamond you’d be crossing one-lane on and off ramps, not half of one of the major roads each time.

edward28 2y ago

Roadguyrob has a video detailing this issue. https://youtube.com/watch?v=xlnz04EZpMQ https://youtube.com/watch?v=xlnz04EZpMQ

marcinzm 2y ago
I don't see why this is unique to a divergent diamond as it only applies to non-light controlled points of conflict of which there are at most two in both designs...

Piskvorrr 2y ago

Four crossing points (two with traffic lights, in this case), whereas for a "normal" interchange, you'd get...also four crossing points. diverging diamond: https://www.openstreetmap.org/directions?engine=fossgis_osrm_foot&route=38.81993%2C-77.63737%3B38.81679%2C-77.64198#map=17/38.81836/-77.63967 https://www.openstreetmap.org/directions?engine=fossgis_osrm... cloverleaf: https://www.openstreetmap.org/directions?engine=fossgis_osrm_foot&route=38.74104%2C-77.52235%3B38.74408%2C-77.51356#map=17/38.74261/-77.51798 https://www.openstreetmap.org/directions?engine=fossgis_osrm...

firesteelrain 2y ago

There is one ten mins from me. It is definitely safer for pedestrians and bike riders. It wasn’t built for golf carts (this is Florida) which really chaps people here. But once they got the lights synchronized, the design works really well. There are little to no accidents. We also have two traffic circles that people call murder circles. The main one has high incident of traffic accidents albeit very very minor in terms of damage and almost no injury.

skywhopper 2y ago

There’s actually fewer crossings involved, so safety for pedestrians should improve as well. But notably these interchanges are often in extremely pedestrian-hostile areas anyway, but it seems more likely that a newly constructed interchange will make at least some attempt to accommodate pedestrians, whereas interchanges built 30+ years ago often ignore pedestrian concerns entirely.

aidenn0 2y ago

This specific interchange looks superior to both a traditional diamond and a cloverleaf for pedestrians. All crossing points are controlled by a light (unlike a cloverleaf), and you don't have to worry about cars taking an unprotected left-turn into you: https://www.google.com/maps/@38.8171139,-77.6412514,3a,75y,344.55h,77.81t/data=!3m6!1e1!3m4!1sOgBPt36zM9RFaYeNTw3d9Q!2e0!7i16384!8i8192?hl=en&entry=ttu https://www.google.com/maps/@38.8171139,-77.6412514,3a,75y,3... [edit] The westbound on-ramp crossing appears to not be protected by a light[1], so would be similar to a cloverleaf onramp; still it's "not bad" as far as non-human-scale interchanges go. 1: https://www.google.com/maps/@38.8191922,-77.6383384,3a,75y,278.34h,98.68t/data=!3m6!1e1!3m4!1sHLmf7t9gWjUjWBTylBMprg!2e0!7i16384!8i8192?hl=en&entry=ttu https://www.google.com/maps/@38.8191922,-77.6383384,3a,75y,2...

presentation 2y ago

Anywhere with an intersection this large seems like it is inherently hostile to pedestrians to begin with.

JeremyNT 2y ago

It seems OK as pictured in the article with a dedicated MUP on one side of the formation. There's probably no interchange design for this volume of traffic that will work all that well for pedestrians and cyclists, though.