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[Beltway]

NJ Turnpike's 3/3/3/3 setup is mostly for roadway management. If you get an accident in one set of lanes, you can shift traffic over to the next set. It also makes overnight construction easy - just close one roadway and set your crews up as you like. However, these are things you can also do when you have a single roadway with 6 lanes by partitioning off 3 of them... and you could easily have 7-8 lanes in the same ROW as 3/3.

A 4-lane directional roadway is the widest before per-lane capacities start declining as more lanes are added.  A 3x3 has significantly more capacity than a 6-lane roadway, and has operational advantages also.

[Steve]

NJ Turnpike's 3/3/3/3 setup is mostly for roadway management. If you get an accident in one set of lanes, you can shift traffic over to the next set. It also makes overnight construction easy - just close one roadway and set your crews up as you like. However, these are things you can also do when you have a single roadway with 6 lanes by partitioning off 3 of them... and you could easily have 7-8 lanes in the same ROW as 3/3.

A 4-lane directional roadway is the widest before per-lane capacities start declining as more lanes are added.  A 3x3 has significantly more capacity than a 6-lane roadway, and has operational advantages also.

3x3 compared to 6, yes. What about 3x3 compared to 7? You'd have to be under 2,100 per lane with 7 lanes to dip below capacity with 3x3 if it's ideal (2400). And when you consider two shoulders plus guiderails, you could probably get 8 in there - I think it's no contest that 8 does better than 3x3.

[Beltway]

NJ Turnpike's 3/3/3/3 setup is mostly for roadway management. If you get an accident in one set of lanes, you can shift traffic over to the next set. It also makes overnight construction easy - just close one roadway and set your crews up as you like. However, these are things you can also do when you have a single roadway with 6 lanes by partitioning off 3 of them... and you could easily have 7-8 lanes in the same ROW as 3/3.

A 4-lane directional roadway is the widest before per-lane capacities start declining as more lanes are added.  A 3x3 has significantly more capacity than a 6-lane roadway, and has operational advantages also.

3x3 compared to 6, yes. What about 3x3 compared to 7? You'd have to be under 2,100 per lane with 7 lanes to dip below capacity with 3x3 if it's ideal (2400). And when you consider two shoulders plus guiderails, you could probably get 8 in there - I think it's no contest that 8 does better than 3x3.

But then you have the problem of how many lanes you need to cross to get to an exit, or how many lanes are between a vehicle and a shoulder.  With 4 lanes you have to cross at most one lane to get to a shoulder in an emergency, assuming that there is a full left shoulder.

If you need 8 lanes directional, it could be 4x4.

I would much rather see dual-divided for anything 10 lanes or wider.

[kphoger]

If you need 8 lanes directional, it could be 4x4.

Not in the same ROW constraints.

[Beltway]

If you need 8 lanes directional, it could be 4x4.

Not in the same ROW constraints.

That assumes that there are such 'constraints'. 

Eight lanes with only 2 shoulders is not an efficient design.

[kphoger]

That assumes that there are such 'constraints'. 

Well, yes I did make the assumption, since the post you were replying to gave ROW constraints:

3x3 compared to 6, yes. What about 3x3 compared to 7? You'd have to be under 2,100 per lane with 7 lanes to dip below capacity with 3x3 if it's ideal (2400). And when you consider two shoulders plus guiderails, you could probably get 8 in there - I think it's no contest that 8 does better than 3x3.

[Beltway]

That assumes that there are such 'constraints'.  

Well, yes I did make the assumption, since the post you were replying to gave ROW constraints:

3x3 compared to 6, yes. What about 3x3 compared to 7? You'd have to be under 2,100 per lane with 7 lanes to dip below capacity with 3x3 if it's ideal (2400). And when you consider two shoulders plus guiderails, you could probably get 8 in there - I think it's no contest that 8 does better than 3x3.

That assumes that there are such 'constraints'.  

Well, yes I did make the assumption, since the post you were replying to gave ROW constraints:

3x3 compared to 6, yes. What about 3x3 compared to 7? You'd have to be under 2,100 per lane with 7 lanes to dip below capacity with 3x3 if it's ideal (2400). And when you consider two shoulders plus guiderails, you could probably get 8 in there - I think it's no contest that 8 does better than 3x3.

A rather artificial constraint, as I don't know of any situation where such a decision needed to be made (8 lane roadway rather than 3x3).

[Steve]

That assumes that there are such 'constraints'. 

Well, yes I did make the assumption, since the post you were replying to gave ROW constraints:

3x3 compared to 6, yes. What about 3x3 compared to 7? You'd have to be under 2,100 per lane with 7 lanes to dip below capacity with 3x3 if it's ideal (2400). And when you consider two shoulders plus guiderails, you could probably get 8 in there - I think it's no contest that 8 does better than 3x3.

That assumes that there are such 'constraints'. 

Well, yes I did make the assumption, since the post you were replying to gave ROW constraints:

3x3 compared to 6, yes. What about 3x3 compared to 7? You'd have to be under 2,100 per lane with 7 lanes to dip below capacity with 3x3 if it's ideal (2400). And when you consider two shoulders plus guiderails, you could probably get 8 in there - I think it's no contest that 8 does better than 3x3.

A rather artificial constraint, as I don't know of any situation where such a decision needed to be made (8 lane roadway rather than 3x3).

It's not artificial, I'm talking about a better use of the current 3x3 space as an 8 lane roadway. That's a very real constraint, even if the decision is not one that needs to be made.

[blawp]

Needs moar parclos in AZ. The diamonds are really inefficient.

[Beltway]

A rather artificial constraint, as I don't know of any situation where such a decision needed to be made (8 lane roadway rather than 3x3).

It's not artificial, I'm talking about a better use of the current 3x3 space as an 8 lane roadway. That's a very real constraint, even if the decision is not one that needs to be made.

I've never heard of any highway agency considering such a thing.  IMO it would be a monstrosity to put that many lanes on a directional roadway.

NJTP has already widened a long 3x3x3x3 section to 4x3x3x4, and could do more if needed.  That has more capacity than 8x8, and has operational advantages as well.

[Steve]

A rather artificial constraint, as I don't know of any situation where such a decision needed to be made (8 lane roadway rather than 3x3).

It's not artificial, I'm talking about a better use of the current 3x3 space as an 8 lane roadway. That's a very real constraint, even if the decision is not one that needs to be made.

I've never heard of any highway agency considering such a thing.  IMO it would be a monstrosity to put that many lanes on a directional roadway.

NJTP has already widened a long 3x3x3x3 section to 4x3x3x4, and could do more if needed.  That has more capacity than 8x8, and has operational advantages as well.

The real point is, they don't need more capacity there, so it's a moot point. The 4x4 section was to add an HOV lane, the only one left in the state (and possibly on its way out) except for PANYNJ approaches. It actually necks to 3x3 at Interchange 13, so it's not all that much help anyway. The points that have been made about safety re: shoulder availability and number of lane changes are ones that stick with me.

[SSOWorld]

When I was in the Phoenix area last year, I took all three loops (starting with the partially constructed 303 that morning) and just plain gawked at the stacks.  I especially appreciated the stack when I went under it on I-17.  The short stack is nice too - but compare nothing to the SuperSanTan - red and all!  I was last in Phoenix as a kid in 1983(ish) and back then the Superstition freeway ended at Gilbert Road and was 2 or 3 lane nearly all the way - the short stack didn't exist and the Stack was not all there.  Now with 5-6 lane Superstition, all those loops and stacks - I just was plain amazed by the architecture. 

Phoenix grows out - not up, and the freeways accommodate for it.  They can build them that wide there unlike NYC, Chicago, Philly SureKill, Pittsburgh, etc.  Interchanges can be large enough to prevent traffic from slowing down as it transitions from road to road (just like Texas).  The freeways grew as the metro area grew so (IMO) the chance of NIMBYism was less (Though it does exist)

[qguy]

Phoenix grows out - not up…

Funny you should put it like that. One of the biggest reasons that Phoenix is threatening to overtake Philadelphia as the county's 5th largest city (although Phila did show growth in the 2010 census for the first time since 1950) is that it has been annexing neighboring populated land area. Philadelphia hasn't had that option since the 1850s (and probably wouldn't even want to do it now if it could).

Not that I'm complaining. If neighboring communities want to throw their lot in with Phoenix, that's their business.

[blawp]

The stacks in the inland empire are more impressive than the ones in Phoenix, a city that cannot comprehend a ParClo.

[NE2]

The stacks in the inland empire are more impressive than the ones in Phoenix, a city that cannot comprehend a ParClo.

What the hell is wrong with you?

[blawp]

The stacks in the inland empire are more impressive than the ones in Phoenix, a city that cannot comprehend a ParClo.

What the hell is wrong with you?

Nope.

[Steve]

The stacks in the inland empire are more impressive than the ones in Phoenix, a city that cannot comprehend a ParClo.

What the hell is wrong with you?

He needs an 85 mph ride on I-366.

[kphoger]

 

(we need a shaking-my-head-in-disappointment emoticon)

[Takumi]

(we need a shaking-my-head-in-disappointment emoticon)

How about ?

[Steve]

(we need a shaking-my-head-in-disappointment emoticon)

How about ?

[kphoger]

(we need a shaking-my-head-in-disappointment emoticon)

How about ?

No, no, not all like that....  Or maybe.....  Exactly.

[blawp]

When the parclo at the 17 and Carefree Highway was built you would've thought ADOT landed someone on the moon with the way they were educating the public.
Post Merge: May 16, 2012, 06:50:16 PMThe hilarious thing about that parclo though is that they designed it so that it doesn't eliminate any phases from the signal. lol o ADOT.

[Brandon]

The stacks in the inland empire are more impressive than the ones in Phoenix, a city that cannot comprehend a ParClo.

What.  The.  Fuck?

Dude, find yourself a parclo and a cheap motel room.  Diamonds work just fine for many applications (and to be honest, LA had a lot of them too, when I took I-5 through town).  As for stacks, a four-level stack is impressive whether it is in LA, Phoenix, Houston, or Detroit.

[agentsteel53]

the thing Phoenix cannot comprehend is a single route number for the through highway.  I-10 and US-60 both exit off themselves at least once, and the only north-south route which is in any way "through" is I-17 and that ends as a staggeringly confusing square loop which somehow manages to intersect I-10 twice.

Phoenix's obsession with maintaining an almost completely rectilinear freeway grid leads to driver confusion.  what's wrong with a road that deviates 5 degrees from a pure cardinal direction, as opposed to making several sharp turns downtown?

[Compulov]

the thing Phoenix cannot comprehend is a single route number for the through highway.  I-10 and US-60 both exit off themselves at least once, and the only north-south route which is in any way "through" is I-17 and that ends as a staggeringly confusing square loop which somehow manages to intersect I-10 twice.

Phoenix's obsession with maintaining an almost completely rectilinear freeway grid leads to driver confusion.  what's wrong with a road that deviates 5 degrees from a pure cardinal direction, as opposed to making several sharp turns downtown?

Wouldn't that have more to do with when I-10 was built and the availability of land/right of way at that time? Where does I-10 exit off itself? I've driven that section of I-10 quite often (well often for someone who doesn't live in the area) and it always seemed fairly obvious to me that you were just taking a wide 90 degree curve rather than some sort of long ramp. I do agree that 90 degree turns are somewhat unusual for a freeway, though not unheard of. It *is* confusing as an out-of-towner when you're aiming to get back to the freeway from surface streets and don't recall if you need to head north or west (or south or east) to get back to I-10...