Full CFI?

[MCRoads]

I know there are CFIs with the Main street having crossovers, and the perpendicular road not, but are there any "full CFIs" ? As in, both streets have crossovers?

[Brandon]

Something like this: Woodward Avenue & 8 Mile Road, Detroit?

[tradephoric]

There was a full CFI proposed for US-20/26 in Caldwell, Idaho:


There is also a full PFI proposed for US 41 / SR-54 in Land "˜O Lakes, Florida:


^A simple Michigan Left would probably function just as well as these two proposed intersections. 

[Scott5114]

Is maintenance on one of these called "CFI care"?

(say it out loud)

[MCRoads]

LOL. i wish ODOT would make one in OKC.

[aztoucan]

4100 south and Bangerter hwy.  West Valley City,UT


iPhone

[kphoger]

4100 south and Bangerter hwy.  West Valley City,UT

Awesome!  Thanks for posting it.

[MCRoads]

4100 south and Bangerter hwy.  West Valley City,UT

Awesome!  Thanks for posting it.

Dude, that's cool! It does exist!!!

Too bad it might be torn out if/when Bangarter Hwy is turned into an expressway.

[US 89]

4100 south and Bangerter hwy.  West Valley City,UT

Awesome!  Thanks for posting it.

Dude, that's cool! It does exist!!!

Too bad it might be torn out if/when Bangarter Hwy is turned into an expressway.

I've been through that intersection many times, but I had no idea that the left-turn movements from 4100 South were crossovers as well. I had to run through all the other CFIs on Bangerter to make sure there wasn't another four-way CFI like this one.

And yes, the plan is to convert Bangerter into a freeway, but UDOT is focusing more on the southern half right now. Of the 11 intersections that remain to be converted into interchanges, 4100 South is listed as priority 9, so this intersection is probably going to stick around a while.

[johndoe]

This site is pretty cool, although I'm not sure who updates the lists (you can filter by interchange/intersection type, location), how they get the information, and why it hasn't been updated in quite a while:

http://www.continuousflowintersections.org/

[Joe The Dragon]

There was a full CFI proposed for US-20/26 in Caldwell, Idaho:


There is also a full PFI proposed for US 41 / SR-54 in Land "˜O Lakes, Florida:


^A simple Michigan Left would probably function just as well as these two proposed intersections.

Trains will mess up the Continuous Flow

[MCRoads]

[snip!]

There is also a full PFI proposed for US 41 / SR-54 in Land "˜O Lakes, Florida:


^A simple Michigan Left would probably function just as well as these two proposed intersections.

Trains will mess up the Continuous Flow

trains will mess up any intersection, including the proposed SPUI.

[Roadsguy]

There is also a full PFI proposed for US 41 / SR-54 in Land "˜O Lakes, Florida:

Holy crap, that intersection is huge! Contender for the biggest?

[hotdogPi]

There is also a full PFI proposed for US 41 / SR-54 in Land "˜O Lakes, Florida:

Holy crap, that intersection is huge! Contender for the biggest?

It's only proposed, not reality.

[Roadsguy]

There is also a full PFI proposed for US 41 / SR-54 in Land "˜O Lakes, Florida:

Holy crap, that intersection is huge! Contender for the biggest?

It's only proposed, not reality.

Yeah, but if it were built it seems it should be a contender for the biggest in the country.

[Tom958]

This is the first CFI I ever encountered, messing around on Google Earth before I'd even heard of the CFI concept. My recollection is that it had displaced left turns on every entry, though I could be wrong. When I first discovered it, it was all at grade, though (per Streetview)  an elevated metro was built sometime before 2009 and the two north-south flyovers sometime before 2014. I encourage you to drop the Streeview dude in the middle and have a look at things then and now.

https://www.google.com/maps/@25.7676758,-100.2922612,409m/data=!3m1!1e3

[jeffandnicole]

The absolute first CFI I believe is where US 130 and NJ 168 in Collingswood/Haddon Twp, NJ just outside of Camden here: https://goo.gl/maps/PsPw5PMEKZ22 .  It was actually built back in the 1940's or 1950's, replacing an elongated traffic circle.  Clearly it was something wayyyyy before its time as the next one wasn't built anywhere from what I can tell for another 50 years or so (and it was proclaimed to be the first in America by the local paper or engineers, but this one in NJ clearly existed for decades already).

The turn lanes are much shorter than in some of the newer examples, and while the CFI function is available to turn left from 130 to 168 in either direction, you can't turn left from 168 to 130 (nearby streets allow for that movement though). 

This intersection still functions quite well even in very heavy traffic conditions, although due to the slight curve on 130 and the narrow lanes, it can be a bit unnerving for someone not used to the area, or traveling alongside a truck (or for the truck drivers themselves)!  Until the traffic light system was upgraded as part of (believe it or not) the I-295/I-76/NJ 42 interchange project, it also used to feature horizontal 8" traffic lights, as shown in this 2008 GSV: https://goo.gl/maps/g9kmsPG6M6N2

[tradephoric]

The absolute first CFI I believe is where US 130 and NJ 168 in Collingswood/Haddon Twp, NJ just outside of Camden here: https://goo.gl/maps/PsPw5PMEKZ22 .  It was actually built back in the 1940's or 1950's, replacing an elongated traffic circle.  Clearly it was something wayyyyy before its time as the next one wasn't built anywhere from what I can tell for another 50 years or so (and it was proclaimed to be the first in America by the local paper or engineers, but this one in NJ clearly existed for decades already).

The US 130 and NJ 168 intersection in NJ is actually known as a parallel flow intersection (PFI).  Here's a website that lists some advantages of PFI's over CFI's and also looks at when to choose PFIs (or CFIs for that matter) over modern roundabout designs:

PFI advantages over continuous flow intersection (CFI):

-More intuitive (left turn is not displaced)
-Requires 50% less approach length
-Lower risk of misjudged crossover maneuver and head-on collisions
-Lower risk with improper turns (e.g. improper left turn at CFI can be high speed crash)
-Results in more space between adjacent main street intersections for lane changing
-Fewer property and driveway impacts
-No overhead guide signs (standard signage only for the PFI)
-Slightly higher capacity with more right turn volume (CFI slightly higher with more left turn volume)
-Simpler signal timing, operation and design
-Faster conversion of existing intersection if no changes (lane addition or lengthening) of left turn lanes

Choosing between the PFI and CFI is largely site dependent. The interchange (or grade separation) should be the option of last resort when the roundabout and two phase at-grade designs are shown to be insufficient to accommodate design year traffic volumes. Interchanges are expensive, take a long time to clear regulations, have higher impacts and often degrade operation on the arterial (in favor of the freeway movement).

PFI advantage over modern roundabout:

-Much higher capacity than three or four lane roundabout

In general, GFParsons recommends the following order of preference for intersection designs based on capacity needs

1.  Modern roundabout — for low to medium traffic volumes (< 4,500 vph) or unless site conditions dictate otherwise such as 3+ approach lanes or very high cost impacts

2.  2-phase signal — generally for high traffic volumes (> 4,500 vph) — the PFI and CFI can accommodate traffic volumes exceeding 10,000 vehicles per hour with 3 or 4 through lanes

The modern roundabout and 2-phase intersections (PFI and CFI) are not competing designs but rather have different traffic capacities. The modern roundabout should be treated as preferred to any signalized intersection where the roundabout has adequate capacity (to a maximum of three circulating lanes up to approx. 4,500 vehicles per hour and maximum two approach lanes). This is due to the roundabout's superior safety and other advantages over signals. But when traffic volumes exceed the capacity of the roundabout, the PFI and CFI should be considered preferable to interchange construction.
http://gfparsons.com/pfi/

I also stumbled upon a model of the PFI concept they are considering in Florida:
https://www.youtube.com/watch?v=9zzRrem87cQ

[UCFKnights]

The simulation seems to indicate a CFI requires a minimum of 2 cycles to make a left, and often 3. How does that effect things in practice? I guess shorter cycles is supposed to help prevent the way of that 2-3 cycles to make a left be not so bad? It really only feels like a 2 phase for traffic going straight.

[jakeroot]

The simulation seems to indicate a CFI requires a minimum of 2 cycles to make a left, and often 3. How does that effect things in practice? I guess shorter cycles is supposed to help prevent the way of that 2-3 cycles to make a left be not so bad? It really only feels like a 2 phase for traffic going straight.

With the CFI, more movements can occur at once than at a normal intersections. So although there are more signals, there's less waiting (at least in theory).

[UCFKnights]

The simulation seems to indicate a CFI requires a minimum of 2 cycles to make a left, and often 3. How does that effect things in practice? I guess shorter cycles is supposed to help prevent the way of that 2-3 cycles to make a left be not so bad? It really only feels like a 2 phase for traffic going straight.

With the CFI, more movements can occur at once than at a normal intersections. So although there are more signals, there's less waiting (at least in theory).

It seems to enter the left turning lane, you have a 50% chance of getting red, then a 100% chance of red when trying to cross the main intersection, and 100% chance of red when moving back to the right side of the road. What is the time it takes if you get all 3 reds (considering 2 are guaranteed)?

[tradephoric]

It seems to enter the left turning lane, you have a 50% chance of getting red, then a 100% chance of red when trying to cross the main intersection, and 100% chance of red when moving back to the right side of the road. What is the time it takes if you get all 3 reds (considering 2 are guaranteed)?

Coming to a guaranteed red isn't so bad if you can turn when there are available gaps in traffic.  Unfortunately, this isn't possible at a PFI design.  That's why I think Median U-Turns are a much more elegant solution as drivers who come to a median u-turn can turn left on red at the crossover when there are available gaps.  But I think with any innovative intersection that eliminates direct left turns, people get hung up with the "relatively minor"  delays that left-turning traffic may experience, and don't focus on the improved traffic flow of the entire network.  In the video below, the driver has a 100% chance of traveling through 124 consecutive green lights, traveling over 40 miles for nearly an hour without hitting a red light.  This drive was only possible because of innovative intersections that eliminate inefficient left turn phases.   

https://www.youtube.com/watch?v=mb2R2fPB1nE

Just imagine driving through Orlando without ever hitting a red light.  Like most cities, Orlando has a bunch of conventional signals with inefficient left turn phases that kills good progression.  Which is  a shame, because many major Florida arterials would be perfect candidates for some innovative intersection designs - since many have wide medians and you have some room to play with innovative designs that redirect those inefficient lefts.  It's good to see that Florida is at least considering some innovative intersections like the PFI, even if it has its faults.

EDIT: The Michigan boulevard starts about 20 seconds into the video.  The first 20 seconds is along a conventional street with traffic signals seemingly every 200 feet apart (maybe a slight exaggeration).  Once you get to the boulevard section, the spacing of traffic signals dramatically increases.  You just don't need traffic signals servicing every strip mall, church, school, or business along a median u-turn corridor.  Having a PFI or CFI at major intersections doesn't really eliminate the need for all those "minor" signals between the major ones, thus your improvement in signal progression won't be that great with CFIs and PFIs.

[jeffandnicole]

The absolute first CFI I believe is where US 130 and NJ 168 in Collingswood/Haddon Twp, NJ just outside of Camden here: https://goo.gl/maps/PsPw5PMEKZ22 .  It was actually built back in the 1940's or 1950's, replacing an elongated traffic circle.  Clearly it was something wayyyyy before its time as the next one wasn't built anywhere from what I can tell for another 50 years or so (and it was proclaimed to be the first in America by the local paper or engineers, but this one in NJ clearly existed for decades already).

The US 130 and NJ 168 intersection in NJ is actually known as a parallel flow intersection (PFI).  Here's a website that lists some advantages of PFI's over CFI's and also looks at when to choose PFIs (or CFIs for that matter) over modern roundabout designs:

PFI advantages over continuous flow intersection (CFI):

-More intuitive (left turn is not displaced)
-Requires 50% less approach length
-Lower risk of misjudged crossover maneuver and head-on collisions
-Lower risk with improper turns (e.g. improper left turn at CFI can be high speed crash)
-Results in more space between adjacent main street intersections for lane changing
-Fewer property and driveway impacts
-No overhead guide signs (standard signage only for the PFI)
-Slightly higher capacity with more right turn volume (CFI slightly higher with more left turn volume)
-Simpler signal timing, operation and design
-Faster conversion of existing intersection if no changes (lane addition or lengthening) of left turn lanes

Choosing between the PFI and CFI is largely site dependent. The interchange (or grade separation) should be the option of last resort when the roundabout and two phase at-grade designs are shown to be insufficient to accommodate design year traffic volumes. Interchanges are expensive, take a long time to clear regulations, have higher impacts and often degrade operation on the arterial (in favor of the freeway movement).

Because New Jersey is New Jersey, many of these don't apply fully, but are nonetheless appreciated.  In my example:

There is overhead signage, but mostly due to ROW constraints.  Actually the signage supports are an interesting feature.  They look like this: https://goo.gl/maps/bCcMeEFN8L92 .  Clearly they are decades old (probably dates back to when the intersection was built), and I can't think of another similar example like it elsewhere in the state.  Obviously newer signage has been installed on them over the past several years.

Because of the X shape of the intersection, right turns are a pain in the ass from 130.  From 168, they're simply odd.  168 North to 130 North is basically a straight movement with clarification you can't turn right on red: https://goo.gl/maps/EKGCBVBhwb62 However, 168 South to 130 South is just odd: It's not controlled by a traffic light, and the movement past the crosswalk isn't controlled at all, unlike the rest of the crosswalk.  Just slightly past this point is a stop sign where one would merge onto 130 South. https://goo.gl/maps/fh1tSMi2a5w

That said, many of the other items mentioned of a PFI do match, at least in some form, the former and current features of the intersection. 

How many PFI's are there in the country?

[tradephoric]

How many PFI's are there in the country?

I guess this intersection outside Columbus would be considered a PFI.  It's a T-intersection only along one leg though.
https://www.google.com/maps/@40.1164973,-83.0347524,100m/data=!3m1!1e3

Apart from America, they got one proposed in Australia (i think it's a PFI after i sort out the cars driving on the opposite side of the road):
https://www.youtube.com/watch?time_continue=39&v=86X7XkBX7Vk

[tradephoric]

Here is a cross between a PFI and a quadrant intersection in Bloomington, Indiana.  There is no commercial development on the corner parcel.
https://www.google.com/maps/@40.4883592,-88.9528379,395m/data=!3m1!1e3

Here is a full blown quadrant intersection in Bloomfield Hills, Michigan with commercial development on the corner.  Operationally, it functions very similar to a PFI.
https://www.google.com/maps/@42.5455348,-83.2834547,271m/data=!3m1!1e3