Favorite Interchange Type?

[jakeroot]

Is it practical to have interchanges between two surface-level arterials?

I think so. Over- or under-passes can blight the landscape, so they have to be exceptionally well-designed. But if you have two extraordinarily busy arterials meeting, and a standard junction isn't cutting it, I think a grade-separated junction is a good idea. Parallel-flow intersections are becoming popular where left turn volumes are high, but these junctions take up an exceptional amount of land; If you can squeeze a tight SPUI or diamond in to that space instead, I'd prefer that (less pedestrian crossings, better overall flow, etc).

[20160805]

Is it practical to have interchanges between two surface-level arterials?

I think so. Over- or under-passes can blight the landscape, so they have to be exceptionally well-designed. But if you have two extraordinarily busy arterials meeting, and a standard junction isn't cutting it, I think a grade-separated junction is a good idea. Parallel-flow intersections are becoming popular where left turn volumes are high, but these junctions take up an exceptional amount of land; If you can squeeze a tight SPUI or diamond in to that space instead, I'd prefer that (less pedestrian crossings, better overall flow, etc).

I really like SPUIs, personally, but I have one question - is it necessary to have three phases?  The left turning people could just go at the regular green, get their own separate turning lane, and wait until the oncoming traffic is clear, couldn't they?

Either way, I'm fine with either and besides, if you have these, not a lot of traffic lights, and not too much cross traffic, you can have at least 40-45 mph speed limits, don't you think? 

In any case, thank you for your input; have a nice day.

[jakeroot]

Is it practical to have interchanges between two surface-level arterials?

I think so. Over- or under-passes can blight the landscape, so they have to be exceptionally well-designed. But if you have two extraordinarily busy arterials meeting, and a standard junction isn't cutting it, I think a grade-separated junction is a good idea. Parallel-flow intersections are becoming popular where left turn volumes are high, but these junctions take up an exceptional amount of land; If you can squeeze a tight SPUI or diamond in to that space instead, I'd prefer that (less pedestrian crossings, better overall flow, etc).

I really like SPUIs, personally, but I have one question - is it necessary to have three phases?  The left turning people could just go at the regular green, get their own separate turning lane, and wait until the oncoming traffic is clear, couldn't they?

Either way, I'm fine with either and besides, if you have these, not a lot of traffic lights, and not too much cross traffic, you can have at least 40-45 mph speed limits, don't you think? 

Well, it's hard to say. Most SPUIs (nearly all that I can think of) operate with protected left turns. I believe this is because the left turns have to clear a lot of "junction" before reaching the on-ramp (which may present a traffic flow issue when you have four or five cars that have to clear the intersection). There are a couple of SPUIs that operate with permissive phasing (here and here), but they're only half-SPUIs; the latter doesn't even half an overpass.

Personally, I think you could offset the left turns enough that four or five cars could wait in the intersection, each line of cars sitting next to each other (passenger side to passenger side). As long as the protected left turn lags behind the permissive phase, I don't think traffic flow would be an issue (four or five cars clearing the intersection, blocking cars trying to go on green).

If I have a moment, I'll make a mock-up of what I'm thinking.

In any case, thank you for your input; have a nice day.

[cappicard]

I just drove through the newly reconstructed DDI at 95th St and I-35 in Lenexa. It opened up for traffic yesterday.

It's quite nice. I just need to make sure I'm not in the left lane when entering it on 95th St if not turning left. [emoji5]


iPhone

[20160805]

Is it practical to have interchanges between two surface-level arterials?

I think so. Over- or under-passes can blight the landscape, so they have to be exceptionally well-designed. But if you have two extraordinarily busy arterials meeting, and a standard junction isn't cutting it, I think a grade-separated junction is a good idea. Parallel-flow intersections are becoming popular where left turn volumes are high, but these junctions take up an exceptional amount of land; If you can squeeze a tight SPUI or diamond in to that space instead, I'd prefer that (less pedestrian crossings, better overall flow, etc).

I really like SPUIs, personally, but I have one question - is it necessary to have three phases?  The left turning people could just go at the regular green, get their own separate turning lane, and wait until the oncoming traffic is clear, couldn't they?

Either way, I'm fine with either and besides, if you have these, not a lot of traffic lights, and not too much cross traffic, you can have at least 40-45 mph speed limits, don't you think? 

Well, it's hard to say. Most SPUIs (nearly all that I can think of) operate with protected left turns. I believe this is because the left turns have to clear a lot of "junction" before reaching the on-ramp (which may present a traffic flow issue when you have four or five cars that have to clear the intersection). There are a couple of SPUIs that operate with permissive phasing (here and here), but they're only half-SPUIs; the latter doesn't even half an overpass.

Personally, I think you could offset the left turns enough that four or five cars could wait in the intersection, each line of cars sitting next to each other (passenger side to passenger side). As long as the protected left turn lags behind the permissive phase, I don't think traffic flow would be an issue (four or five cars clearing the intersection, blocking cars trying to go on green).

What do you mean by "clear the intersection"?

Either way, thank you - I wasn't sure and I don't want traffic flow to be too much of a problem.

If I have a moment, I'll make a mock-up of what I'm thinking.

Thank you very much as I'm not sure I really understand. 

[kphoger]

Roundabout interchange.  Full roundabout, not dogbone.

[20160805]

Roundabout interchange.  Full roundabout, not dogbone.

Roundabout interchanges, unlike roundabouts/traffic circles/whatever themselves, are pretty cool.

[CrystalWalrein]

Four-level stack, especially those braided with local diamond or loop interchanges (the ON 400 and ON 407 stack comes to mind). The interchange between the Garden State Parkway and Atlantic City Expressway should have been built as one during the recent construction.

[SeriesE]

SPUI for freeway-to-arterial and full stack for freeway-to-freeway

[CapeCodder]

RI-RO. I-81 in VA has them in the mountainous areas.

[I-55]

Roundabout interchange.  Full roundabout, not dogbone.

I'm going to assume by full you mean "A" and by dogbone you mean "B"?

I don't think by dogbone you mean"C".

[ilpt4u]

Call me crazy, but I like Trumpets, most commonly seen on Toll Roads/Turnpikes. Single intersection/light for the crossroad; freeflowing for the Freeway/Tollway

Its simple and it works, even if it does require an additional overpass for the Trumpet ramps

[Henry]

Being from Chicago, I'm impartial to the Circle Interchange, which has the coolest design of any freeway-freeway interchange ever! For freeway-surface road interchanges, I love the SPUI.

[kphoger]

Roundabout interchange.  Full roundabout, not dogbone.

I'm going to assume by full you mean "A" and by dogbone you mean "B"?

I don't think by dogbone you mean"C".

Correct.  The dogbone in 'C' is missing an end.  But the one just to the west is beautiful.

[jmacswimmer]

I'll second SPUI as my favorite for freeway-to-surface.  For freeway-to-freeway I like the full turbine interchange (such as I-85 & I-485 northeast of Charlotte) and the symmetrical stack interchange (such as my local I-70/I-695 exchange...if only I-70 had been completed to I-95 so it could have functioned as designed, and not as it does now with half the ramps overloaded and the other half underloaded).

[Ned Weasel]

Ones that show daring, bold creativity instead of a standardized formula.

https://goo.gl/maps/8r8sHMEy9TRCcNks7
https://goo.gl/maps/ngARw575cr18Xgsv9
https://goo.gl/maps/ipi2Tdv4z67pfhgAA

[SeriesE]

Ones that show daring, bold creativity instead of a standardized formula.

https://goo.gl/maps/8r8sHMEy9TRCcNks7
https://goo.gl/maps/ngARw575cr18Xgsv9
https://goo.gl/maps/ipi2Tdv4z67pfhgAA

The last one looks confusing to drive through.

[Ned Weasel]

Ones that show daring, bold creativity instead of a standardized formula.

https://goo.gl/maps/8r8sHMEy9TRCcNks7
https://goo.gl/maps/ngARw575cr18Xgsv9
https://goo.gl/maps/ipi2Tdv4z67pfhgAA

The last one looks confusing to drive through.

Unlike a lot of western states and some midwestern and southern states, New Jersey is usually great at conveying pertinent information on road signs.  I say "usually," because like every state/DOT/agency, you'll find a few sign arrangements leaving something to be desired.

There's often value in having road design that keeps you on your toes, rather than mile after mile of the same diamond copied and pasted everywhere.  But there is an old saying, "If you can't sign it, don't design it."  And New Jersey usually has no problem signing it.

Also, those intricate windings and connections of roadways, designed for optimal flows and smoothly transitioning movements, are just plain beautiful, both from an aerial perspective and from a driver's point of view.

Oh, and I never had any problem driving through the I-78/I-95/NJTP interchange, but I only remember using it to transition from or to I-95 once in my lifetime, because I tend to stick to I-287 for most things in Central to North Jersey.

[jakeroot]

Unlike a lot of western states and some midwestern and southern states, New Jersey is usually great at conveying pertinent information on road signs.  I say "usually," because like every state/DOT/agency, you'll find a few sign arrangements leaving something to be desired.

Could you expand a bit on what you mean by "a lot of western states"? I don't know crap about the midwest (apart from a brief stint in STL before my roadgeek days), but I would not associate the west with poor road signage.

California gets a bad rap for its height limitations, but the signs themselves, and the information on them, are typically very well designed and of high quality. Oregon and Washington have very good signage overall as well. I won't even touch on Nevada, Idaho, Arizona, Utah, or Colorado, as those states are rarely mentioned as contenders for bad signs, or places that don't sign enough "pertinent information" (whatever that even means?).

[Ned Weasel]

Could you expand a bit on what you mean by "a lot of western states"? I don't know crap about the midwest (apart from a brief stint in STL before my roadgeek days), but I would not associate the west with poor road signage.

California and New Mexico stand out.  Colorado also pisses me off for not signing US 6 in such a way that you could actually follow it by reading the signs (ain't it nice now it just disappears? https://goo.gl/maps/HPZ4Mdyz2gQajkbm8 ).

California gets a bad rap for its height limitations, but the signs themselves, and the information on them, are typically very well designed and of high quality.

I'm not going to call you Shirley, but you can't be serious!  Poor maintenance?  Little to no consistency?  Missing exit numbers all over the place?  Where do I even begin?

Oregon and Washington have very good signage overall as well.

Oregon is good from what I've seen.  Washington is so-so.

I won't even touch on Nevada, Idaho, Arizona, Utah, or Colorado, as those states are rarely mentioned as contenders for bad signs, or places that don't sign enough "pertinent information" (whatever that even means?).

See above regarding Colorado.  And that brings me to my point about why I love New Jersey so much.  They almost always sign all of their US, state, and even county routes in such a way that they can be followed and recognizably approached from any direction, even when there are many of them overlapping and intersecting.  Other states tend to take more of a "Who cares about the secondary routes?" approach.  Kansas gets praised for its road signs, but have you tried following US 169?  It's barely legible in the northbound direction, and it's impossible in the southbound direction (and, as mentioned here: https://www.aaroads.com/forum/index.php?topic=15260.msg2520896#msg2520896, the brand new sign plan doesn't even correct that).  As for US 50, that's an important route, right?  https://goo.gl/maps/CwBhusiqE4NztXbu6  [Sarcasm]How could anyone possibly miss those great, big, freeway-standard signs for it while going 65 MPH in busy I-35 traffic?[/Sarcasm]  I can almost guarantee you NJDOT would include US 50 on the overhead signs without hesitation (although you might see a black background around the shield, but it's not like other states have never committed that [sarcasm]horrible atrocity[/sarcasm]: https://goo.gl/maps/NyG4ydZZc6RJse9X9 ).

And it's not only that, but do you ever need to turn around?  If you're on a divided roadway, chances are you will at least once in a while.  Fortunately, New Jersey has signs all over the place telling you where to do it (relevant example: https://goo.gl/maps/dbkuQ9KFgfWdXB4P9 ).  And, as I've mentioned many times before, New Jersey's method for signing jughandles became the 2009 MUTCD standard!  That's the closest thing to an award for sign design that I've ever heard of.  Okay, Oregon did a decent job with that one, even though it's not standard: https://goo.gl/maps/5He5PY6unxfq5AB9A .  But let's take a look at one closer to home for me: https://goo.gl/maps/LuGUn2efCFgXgFAp9 .  Is there a reason to use use a tiny, overly worded green sign instead of the tried-and-true "ALL TURNS FROM RIGHT LANE?"  As for the turn itself: https://goo.gl/maps/6iAmtY3fnEXSjj1Q8 .  Nice job, KCMO!  Now, in fairness, MoDOT does a better job with the ones closer to St. Louis: https://goo.gl/maps/vk67STYDF5mHuJaP7 .  How about Illinois?  https://goo.gl/maps/r97K5hFjzG5G4ws9A , https://goo.gl/maps/6nJ1ReoSCUfNbg737 .  Since that's a construction zone, I'll just say, I hope that isn't the final draft.  So, let's see a couple of others on an Illinois state highway: https://goo.gl/maps/3PNmT1L6K6FyCBeG6 , https://goo.gl/maps/rKM5Ce1fxyLpDnLA9 .  Um, do those even have any signs at all?

So, all of the above is what I mean by "pertinent information."  New Jersey does what a lot of other states fail to do.  And it's not just states outside of the northeast.  Try following US 1 through Rhode Island: https://goo.gl/maps/adpyuZzAEfcozkyMA , https://goo.gl/maps/uLdNhBF9KrHnAz4D8 .  I mean, come on, it's US One!