Curious has to how many of these intersections have been built, so:
Full
* MO 30 at Summit Road, near Fenton, MO:
http://maps.google.com/maps?hl=en&ie=UTF8&ll=38.504394,-90.457456&spn=0.003619,0.010986&t=k&z=17 (http://maps.google.com/maps?hl=en&ie=UTF8&ll=38.504394,-90.457456&spn=0.003619,0.010986&t=k&z=17)
* BL 55 at IL 9, Bloomington, IL (this one is confusing to drive through given the proximity of other intersection on IL 9; really could use to be an interchange on BL 55)
http://maps.google.com/maps?hl=en&ie=UTF8&ll=40.488068,-88.952769&spn=0.003517,0.010986&t=k&z=17 (http://maps.google.com/maps?hl=en&ie=UTF8&ll=40.488068,-88.952769&spn=0.003517,0.010986&t=k&z=17)
Half
* Big Bend at Geyer Road, Kirkwood, MO:
http://maps.google.com/maps?hl=en&ie=UTF8&ll=38.566757,-90.415179&spn=0.001808,0.005493&t=k&z=18 (http://maps.google.com/maps?hl=en&ie=UTF8&ll=38.566757,-90.415179&spn=0.001808,0.005493&t=k&z=18)
* IL 3 at IL 143, near Wood River, IL:
http://maps.google.com/maps?hl=en&ie=UTF8&ll=38.857823,-90.108565&spn=0.003601,0.010986&t=k&z=17 (http://maps.google.com/maps?hl=en&ie=UTF8&ll=38.857823,-90.108565&spn=0.003601,0.010986&t=k&z=17)
Other/Mutants
* Business 51 at IL 105, Decatur, IL. Two of the turning roadways on one side of the cross road:
http://maps.google.com/maps?hl=en&ie=UTF8&ll=39.822801,-88.957983&spn=0.003551,0.010986&t=h&z=17 (http://maps.google.com/maps?hl=en&ie=UTF8&ll=39.822801,-88.957983&spn=0.003551,0.010986&t=h&z=17)
Haven't seen too many, if any, like that.
Be well,
Bryant
What exactly is a full/half continuous flow intersection, I think I have an idea of what it is from looking at the pictures, but I'm not completely sure......
BigMatt
There's one on Airline Hwy (U.S. 61) in Baton Rouge.
Quote from: BigMatt on June 20, 2010, 04:51:54 PM
What exactly is a full/half continuous flow intersection, I think I have an idea of what it is from looking at the pictures, but I'm not completely sure......
BigMatt
A CFI is an intersection where left turns cross opposing traffic at a signal before the intersection with the cross street. Right turns from the cross street are aligned so they run parallel to the crossed-over left turns. For the purpose of this thread, I'm defining a full CFI as an intersection where the left turns are crossed over for both directions of the main street; a half CFI only has left turns crossed over for one direction (there's probably another name for this design, but I can't recall it at the moment - something turning roadway?).
The Maryland site on odd intersections and interchanges has a diagram of a CFI with left turns crossed over on all roadways:
http://attap.umd.edu/UAID_ags.php?UAIDType=5&iFeature=1 (http://attap.umd.edu/UAID_ags.php?UAIDType=5&iFeature=1)
To add on to Revive 755's explanation: The name "continuous flow" comes from the fact that the main intersection and left-turn crossover signals are all coordinated together, such that once the first signal is green, you should be able to flow continuously through the remainder of the intersection without stopping.
The theory behind CFI's is that by putting the left turns on a separate cross-over roadway, it eliminates left turn signal phasing at the main intersection. When working properly, it should drastically reduce delay at the junction because the signal operates in only two phases (as opposed to the eight phases needed to accommodate all lefts and throughs normally). The drawback to CFI's is a huge right-of-way, higher construction cost, higher maintenance/upkeep cost with the additional signal heads and signs needed, and greater potential for driver confusion.
Adding on to roadfro's comment, another argument used in favor of CFI's (and the one used in the US 61/Baton Rouge case) is that they're cheaper than building an interchange.
BTW, the MD 210/MD 228 (http://maps.google.com/?ie=UTF8&ll=38.664276,-77.017486&spn=0.005914,0.01369&t=k&z=17) junction is an example of a CFI at a 3-way intersection.
Ok, then I'm pretty sure that it's not what I was thinking, and I'm pretty positive that there's none in San Angelo.
BigMatt
Found the alternate name for the half CFI design: "Displaced Left Turn."
http://www.fhwa.dot.gov/publications/research/safety/09056/index.cfm (http://www.fhwa.dot.gov/publications/research/safety/09056/index.cfm)
Found a half CFI in Peoria, IL, at the US 150/IL 40 intersection. This one has the left turn crossover controlled by a yield sign instead of being signalized.
http://maps.google.com/maps?hl=en&ie=UTF8&ll=40.731966,-89.594015&spn=0.003073,0.0103&t=k&z=18 (http://maps.google.com/maps?hl=en&ie=UTF8&ll=40.731966,-89.594015&spn=0.003073,0.0103&t=k&z=18)
http://maps.google.com/maps?hl=en&ie=UTF8&ll=40.731966,-89.594015&spn=0,0.0103&t=k&z=18&layer=c&cbll=40.731055,-89.593509&panoid=CfmHwslf_tuZqoMKXE_8JA&cbp=12,320.54,,0,7.11 (http://maps.google.com/maps?hl=en&ie=UTF8&ll=40.731966,-89.594015&spn=0,0.0103&t=k&z=18&layer=c&cbll=40.731055,-89.593509&panoid=CfmHwslf_tuZqoMKXE_8JA&cbp=12,320.54,,0,7.11)
Quote from: roadfro on June 20, 2010, 06:30:52 PM
To add on to Revive 755's explanation: The name "continuous flow" comes from the fact that the main intersection and left-turn crossover signals are all coordinated together, such that once the first signal is green, you should be able to flow continuously through the remainder of the intersection without stopping.
The theory behind CFI's is that by putting the left turns on a separate cross-over roadway, it eliminates left turn signal phasing at the main intersection. When working properly, it should drastically reduce delay at the junction because the signal operates in only two phases (as opposed to the eight phases needed to accommodate all lefts and throughs normally). The drawback to CFI's is a huge right-of-way, higher construction cost, higher maintenance/upkeep cost with the additional signal heads and signs needed, and greater potential for driver confusion.
And in this day and age of befuddled drivers, do we really need the greater potential for driver confusion? Today's drivers can't even figure out that red lights mean "STOP" and green lights mean "GO" because they're too busy yapping on their cell phones! :pan:
One of the main reasons why I dislike all the new roundabouts that are popping up all over Arizona like weeds except you can't simply spray them with "Round-Up."
Quote from: hm insulators on July 01, 2010, 02:09:55 PM
Arizona like weeds except you can't simply spray them with "Round-Up."
Of course you can't; they're already round :pan:
Here in Utah Land, UDOT has fallen love with CFI's. They are currently in the process of building 3 more here to the 1 already built at 3500 S and bangerter Hwy
Existing built CFI
http://maps.google.com/maps?f=q&source=s_q&hl=en&geocode=&q=3500+south+and+bangerter+&sll=37.0625,-95.677068&sspn=60.806372,134.912109&ie=UTF8&hq=&hnear=Bangerter+Hwy+%26+W+3500+S,+West+Valley+City,+Salt+Lake,+Utah&ll=40.696616,-111.980692&spn=0,0.016469&z=17&layer=c&cbll=40.696619,-111.980808&panoid=a4eLwjceGF_3KPnKPEEPlQ&cbp=12,196.18,,0,5.45
New ones being built
http://www.udot.utah.gov/wego/
They are also in studying other areas in Salt Lake County for places to install these.
http://www.udot.utah.gov/7800South/home.aspx
http://www.udot.utah.gov/main/f?p=100:pg:0:::1:T,V:3029,
Found a combination of a CFI and a Michigan left in the Detroit area:
http://maps.google.com/maps?hl=en&ll=42.371128,-83.274382&spn=0.003357,0.008256&t=h&z=18 (http://maps.google.com/maps?hl=en&ll=42.371128,-83.274382&spn=0.003357,0.008256&t=h&z=18)
Here's a half-CFI in Peoria, IL: http://maps.google.com/?ll=40.731434,-89.592444&spn=0.002785,0.006539&hnear=Davenport,+Scott,+Iowa&t=k&z=18
There's actually a sort of a half-CFI in Eugene, Oregon along Franklin Blvd (OR-99) at Agate Street (http://maps.google.com/maps?q=Franklin+Boulevard+and+E+13th+Ave,+Eugene,+OR&hl=en&ll=44.045575,-123.067517&spn=0.002186,0.005284&sll=44.016151,-123.023701&sspn=0.069996,0.169086&hnear=Franklin+Blvd+%26+E+13th+Ave,+Eugene,+Lane,+Oregon+97403&t=k&z=18), right near the UO campus.
I'm feeling too lazy to look for more. This is just the most recent one I've looked at:
Saltillo, Coahuila
http://g.co/maps/tzcz7 (http://g.co/maps/tzcz7)
Quote from: roadfro on June 20, 2010, 06:30:52 PM
To add on to Revive 755's explanation: The name "continuous flow" comes from the fact that the main intersection and left-turn crossover signals are all coordinated together, such that once the first signal is green, you should be able to flow continuously through the remainder of the intersection without stopping.
The theory behind CFI's is that by putting the left turns on a separate cross-over roadway, it eliminates left turn signal phasing at the main intersection. When working properly, it should drastically reduce delay at the junction because the signal operates in only two phases (as opposed to the eight phases needed to accommodate all lefts and throughs normally). The drawback to CFI's is a huge right-of-way, higher construction cost, higher maintenance/upkeep cost with the additional signal heads and signs needed, and greater potential for driver confusion.
I am not sure if I understand how this is coordinated to have
both continuous-flow, as well as only two phases.
I am guessing that the two phases of the light are "traffic coming from east or west has right of way" and "traffic coming from north or south has right of way".
so, in the east-west situation, let's say eastbound cars want to turn left - northbound. They cross over the westbound lanes, as their signal is green. However, the westbound traffic which does not want to turn is coming westbound. If both have a green light, then we have an intersection with no protected left phase: east-to-north traffic is coming into conflict with westbound traffic.
is this resolved through timing? i.e. the east-to-north turning traffic is given a head start of several seconds before the westbound non-turning traffic is given green?
Here's an animated video that should help you understand the timing (this one has crossovers on all four legs):
http://www.youtube.com/watch?v=6B2NeuXA4lY (http://www.youtube.com/watch?v=6B2NeuXA4lY)
Quote from: kphoger on April 10, 2012, 01:56:00 PM
I'm feeling too lazy to look for more. This is just the most recent one I've looked at:
Saltillo, Coahuila
http://g.co/maps/tzcz7 (http://g.co/maps/tzcz7)
Oh, and here's the GMSV of the diagrammatic sign that the highway department thought might be useful to westbound traffic.
http://g.co/maps/rbgbq (http://g.co/maps/rbgbq)
Quote from: froggie on June 21, 2010, 07:11:27 AM
Adding on to roadfro's comment, another argument used in favor of CFI's (and the one used in the US 61/Baton Rouge case) is that they're cheaper than building an interchange.
BTW, the MD 210/MD 228 (http://maps.google.com/?ie=UTF8&ll=38.664276,-77.017486&spn=0.005914,0.01369&t=k&z=17) junction is an example of a CFI at a 3-way intersection.
Adam, I believe the eastern end of the Md. 200 (InterCounty Connector) toll road will be a CFI at U.S. 1 (Baltimore Avenue) between Laurel and Beltsville.
I believe the state was motivated to build an at-grade CFI (instead of a trumpet interchange, perhaps) because the CSX Capital Subdivision tracks run parallel to (and just east of) U.S. 1.
There's an incomplete one at Shady Oaks Dr & (Future Spencer Rd) in Denton, Tx
Interesting thing is that the left lanes that are left turn only lanes are open even though there is no street to turn left into.
http://maps.google.com/maps?hl=en&ll=33.203343,-97.097479&spn=0.001495,0.003133&t=h&z=19 (http://maps.google.com/maps?hl=en&ll=33.203343,-97.097479&spn=0.001495,0.003133&t=h&z=19)
Quote from: Brian556 on April 11, 2012, 07:56:08 PM
There's an incomplete one at Shady Oaks Dr & (Future Spencer Rd) in Denton, Tx
Interesting thing is that the left lanes that are left turn only lanes are open even though there is no street to turn left into.
http://maps.google.com/maps?hl=en&ll=33.203343,-97.097479&spn=0.001495,0.003133&t=h&z=19 (http://maps.google.com/maps?hl=en&ll=33.203343,-97.097479&spn=0.001495,0.003133&t=h&z=19)
That's not a CFI.
Quote from: kphoger on April 10, 2012, 04:30:07 PM
Here's an animated video that should help you understand the timing (this one has crossovers on all four legs):
http://www.youtube.com/watch?v=6B2NeuXA4lY (http://www.youtube.com/watch?v=6B2NeuXA4lY)
yep, all timing-based. it just stretches the definition of the word "phase", then.
I'm glad there's a second light at the
end of the left-turn "chute" because without it, it would be disastrous if slow-moving traffic did not clear the chute before crossing traffic was released across it.
Quote from: NE2 on April 11, 2012, 07:59:13 PM
Quote from: Brian556 on April 11, 2012, 07:56:08 PM
There's an incomplete one at Shady Oaks Dr & (Future Spencer Rd) in Denton, Tx
Interesting thing is that the left lanes that are left turn only lanes are open even though there is no street to turn left into.
http://maps.google.com/maps?hl=en&ll=33.203343,-97.097479&spn=0.001495,0.003133&t=h&z=19 (http://maps.google.com/maps?hl=en&ll=33.203343,-97.097479&spn=0.001495,0.003133&t=h&z=19)
That's not a CFI.
More specifically, that is (or will be) a High-T intersection.
The US 130/NJ 168 intersection (http://g.co/maps/m58h7) in Collingswood, NJ appears to be a CFI.
Quote from: PennDOTFan on April 15, 2012, 03:45:46 PM
The US 130/NJ 168 intersection (http://g.co/maps/m58h7) in Collingswood, NJ appears to be a CFI.
The earliest design I know of that would qualify, certainly predating any attempt to copyright the design. If I were to design a CFI, I would not pay royalties to the copyright holders and use this as evidence to dispute.
I think the patent expired a few years back - and it appears to have applied only where the turn lanes are grade separated: http://www.google.com/patents/US5049000
Someone else tried to patent a standard spread-out directional interchange like at I-94 and M-10 in Detroit: http://www.google.com/patents/US3107590
There are a bunch of interesting designs in the related patents.
Quote from: kphoger on April 10, 2012, 01:56:00 PM
I'm feeling too lazy to look for more. This is just the most recent one I've looked at:
Saltillo, Coahuila
http://g.co/maps/tzcz7 (http://g.co/maps/tzcz7)
OK, scratch that. It looks like that whole corridor is being upgraded to a freeway, and that intersection in particular is now home to a stacked interchange.
http://maps.google.com/?ll=39.013732,-95.744659&spn=0.006861,0.009645&t=k&z=17
SW 29th and Fairlawn in Topeka: A combination Half-CFI and a Diamond interchange with I-470. The ramps to and from the southeast end at Fairlawn, the ramps to and from the northwest terminate at 29th. The signals at each end of the CFI connector also serve as the signals from WB 470 to Fairlawn and from 29th to WB 470. The ramp from Fairlawn to EB 470 is unsignalized.
Quote from: route56 on April 21, 2012, 09:21:42 PM
http://maps.google.com/?ll=39.013732,-95.744659&spn=0.006861,0.009645&t=k&z=17
SW 29th and Fairlawn in Topeka: A combination Half-CFI and a Diamond interchange with I-470. The ramps to and from the southeast end at Fairlawn, the ramps to and from the northwest terminate at 29th. The signals at each end of the CFI connector also serve as the signals from WB 470 to Fairlawn and from 29th to WB 470. The ramp from Fairlawn to EB 470 is unsignalized.
I don't see how that's like a CFI at all. Am I missing something?
Quote from: kphoger on April 21, 2012, 10:56:44 PM
I don't see how that's like a CFI at all. Am I missing something?
A CFI moves left turning traffic away from the main intersection. In the case of 29th and Fairlawn, the movement affected is Northbound Fairlawn to Westbound 29th. Since the connecting roadway is aligned with the ramps to and from Westbound I-470, it also eliminates a weaving move for traffic from NB Fairlawn to WB I-470.
Quote from: route56 on April 22, 2012, 01:17:35 AM
Quote from: kphoger on April 21, 2012, 10:56:44 PM
I don't see how that's like a CFI at all. Am I missing something?
A CFI moves left turning traffic away from the main intersection. In the case of 29th and Fairlawn, the movement affected is Northbound Fairlawn to Westbound 29th. Since the connecting roadway is aligned with the ramps to and from Westbound I-470, it also eliminates a weaving move for traffic from NB Fairlawn to WB I-470.
The main aspect of the CFI intersection is that there is the one big intersection with left turns split out and separated from the main middle of the intersection, and that such left turns are spaced and signal timed in such a way that once the left turns make the crossover they don't stop at all in the intersection. The above example doesn't follow that at all...it's essentially a split diamond interchange with one two-way connector road in between (instead of two one-way connectors) located adjacent to the intersection of the two cross streets creating the split diamond.
I'd like to add the intersection of US 65/84 and US 61 in Natchez (the eastern terminus of US 65). It looks to be at least a partial CFI.
Quote from: roadfro on April 22, 2012, 05:11:23 AM
The main aspect of the CFI intersection is that there is the one big intersection with left turns split out and separated from the main middle of the intersection, and that such left turns are spaced and signal timed in such a way that once the left turns make the crossover they don't stop at all in the intersection. The above example doesn't follow that at all...it's essentially a split diamond interchange with one two-way connector road in between (instead of two one-way connectors) located adjacent to the intersection of the two cross streets creating the split diamond.
However, if you take the interchange ramps out of the picture, the intersection would function the same way as Revive 755's Wood River example.
If, however, having left turns being separated from the main intersection via a connector road disqualifies an intersection as being a CFI, than the Wood River and Bloomington examples would have to be thrown out.
Quote from: PennDOTFan on April 15, 2012, 03:45:46 PM
The US 130/NJ 168 intersection (http://g.co/maps/m58h7) in Collingswood, NJ appears to be a CFI.
This location looks more like the CFI's cousin: the "parallel flow intersection".
See http://www.paraflow.info/ (http://www.paraflow.info/) for a video with more info.
I don't believe there are any recently built examples of the parallel flow, although the consultant who has a patent on it is trying to promote its use. The main difference between the two types is that in a parallel flow the left turns cross over
after the intersection, while in a CFI the left turns cross over
before the intersection. It seem to me that the CFI would tend to operate more efficiently than the parallel flow, since thru traffic only has to pass 2 signals, whereas it has to pass 3 signals in a parallel flow. The more signals traffic has to pass through, the more difficult it is to properly coordinate them.
The FHWA document on alternative intersections has a more in-depth discussion on both types: http://www.fhwa.dot.gov/publications/research/safety/09060/09060.pdf (http://www.fhwa.dot.gov/publications/research/safety/09060/09060.pdf)
Quote from: 2Co5_14 on April 26, 2012, 10:39:09 PM
Quote from: PennDOTFan on April 15, 2012, 03:45:46 PM
The US 130/NJ 168 intersection (http://g.co/maps/m58h7) in Collingswood, NJ appears to be a CFI.
This location looks more like the CFI's cousin: the "parallel flow intersection".
See http://www.paraflow.info/ (http://www.paraflow.info/) for a video with more info.
I don't believe there are any recently built examples of the parallel flow, although the consultant who has a patent on it is trying to promote its use. The main difference between the two types is that in a parallel flow the left turns cross over after the intersection, while in a CFI the left turns cross over before the intersection. It seem to me that the CFI would tend to operate more efficiently than the parallel flow, since thru traffic only has to pass 2 signals, whereas it has to pass 3 signals in a parallel flow. The more signals traffic has to pass through, the more difficult it is to properly coordinate them.
The FHWA document on alternative intersections has a more in-depth discussion on both types: http://www.fhwa.dot.gov/publications/research/safety/09060/09060.pdf (http://www.fhwa.dot.gov/publications/research/safety/09060/09060.pdf)
Interesting! I had not heard of parallel flow yet. This gives me something to chew on.