Continuous flow intersection

.

Locations outside of Mexico

Listed in order of implementation:

#Oaklyn, New Jersey, New Jersey Route 168 at U.S. Route 130 (Closer to a Parallel Flow Intersection than a CFI).
#Shirley, New York, opened in 1996, at the entrance to Dowling College.cite web | url=http://www.cenews.com/article.asp?id=312 | title=Continuous flow intersections | accessdaymonth=13 June | accessyear=2007 | author=Bruce, Michael G., P.E., and Paul W. Gruner, P.E., P.S. | date=2005-12-28 | year=2005 | month=12 | publisher=CENews.com]
#Accokeek, Maryland, opened in 2000, at the intersection of Routes 210 and 228..
#Baton Rouge, Louisiana, opened in March 2006, at the intersection of Airline Hwy and Siegen Lane.cite web | url=http://www.dotd.louisiana.gov/press/pressrelease.asp?nRelease=627 | title=First 'continuous-flow' intersection in the state opens on Airline today | accessdaymonth=13 June | accessyear=2007 | author=Ruiz de Chavez, Lindsay | date=2006-03-21 | year=2006 | month=03 | publisher=Louisiana Department of Transportation & Development]
#West Valley City, Utah, opened in September 2007,cite web | url=http://www.ksl.com/?nid=148&sid=1818294 | title=Continuous Flow Intersection Opens to Rush Hour Traffic | accessdaymonth=17 September | accessyear=2007 | author=Whit Johnson | publisher=KSL Newsradio] at the intersection of Bangerter Highway and 3500 Southcite web | url=http://www.udot.utah.gov/cfi/ | title=3500 South & Bangerter Highway CFI (Continuous Flow Intersection) | accessdaymonth=13 June | accessyear=2007 | author=Utah Department of Transportation | publisher=Utah Department of Transportation]
#Fenton, Missouri, opened October 2007,cite web | url=http://www.stltoday.com/stltoday/news/stories.nsf/stlouiscitycounty/story/98FA052BF09ED6468625738500198B0C?OpenDocument | title=How do you get through this? | accessdaymonth=31 October | accessyear=2007 | author=Elisa Crouch | publisher=St. Louis Post-Dispatch] at the intersection of Highway 30 and Summit Drive/Gravois Bluffs Blvd.cite web | url=http://www.modot.org/stlouis/links/ContinuousFlowIntersections2.htm | title=Continuous Flow Intersections | accessdaymonth=13 June | accessyear=2007 | author=Missouri Department of Transportation - St. Louis Area District | publisher=Missouri Department of Transportation - St. Louis Area District] .

Operational details

Part of the delay at a regular, high-volume intersection is because of the left-turn cycle of the traffic signals; through-traffic must wait for the traffic turning left. The continuous flow intersection moves the left-turn conflict to the signal cycle of the cross-traffic.

In the diagram to the right, while the east/west traffic is flowing through the intersection, the north/south left-turn traffic is allowed through each of the smaller intersections that are a few hundred feet from the main intersection. When the north/south through traffic is allowed through the main intersection, the north/south left-turn lanes are also allowed through the intersections. All traffic flow is controlled by traffic signals as at a regular intersection.

To reduce confusion regarding the left-turn lane, the left-turn lane and the straight-through lanes are usually separated by a concrete barrier or traffic island. This diagram shows the straight-through lanes offset by one lane through the intersection and are guided by lines painted through the intersection. But this is just a sample configuration; the lanes may be offset by more lanes or none at all.

Nonetheless, due to the provision of traffic between two directions of opposing traffic, some motorists tend to maintain an ongoing criticism of the intersection. Additionally, as in the case of the half-CFI in Accokeek, the offset left-turn traffic reenters the main traffic stream via a half-signal, requiring motorists to merge from a stop condition onto the higher-speed mainline. Motorists sometimes cite discomfort due to this, though conflicts can be reduced through the provision of an adequate acceleration lane and merge area.

This type of intersection can require a significant amount of right-of-way to implement, which is why such configurations are not frequently used in urban areas. However, the amount of land necessary for construction and final operation is still typically less than that of an interchange. Additionally, as there is no grade separation involved, costs are considerably less than that of an interchange alternative.

References

External links

*Federal Highway Administration, [http://www.tfhrc.gov/safety/pubs/04091/10.htm#1023 Alternative Intersection Treatments - CFI]
*University of Maryland, [http://attap.umd.edu/UAID_ags.php?UAIDType=5&iFeature=2 ATTAP] - Animation of a CFI (Quicktime required). Additional information may be accessed via the links on the left side.

*coord|39.90401|N|75.09585|W| Location of a CFI in Oaklyn, New Jersey, USA
*coord|40.826443|N|72.881042|W| Location of a CFI in Shirley, New York, USA
*coord|38.664126|N|77.016928|W| Location of a CFI in Accokeek, Maryland, USA
*coord|30.398914|N|91.054119|W| Location of a CFI in Baton Rouge, Louisiana, USA
*coord|40.696690|N|111.980920|W| Location of a CFI in West Valley City, Utah, USA
*coord|38.504276|N|90.456995|W| Location of a CFI in Fenton, Missouri, USA::"Note that due to the relatively recent installation of the CFI in Baton Rouge, West Valley, UT, and Fenton, MO, some images may not show the existing conditions."
* [http://deseretnews.com/dn/view/0,1249,610152168,00.html Deseret News story about CFI]
* [http://www.ksl.com/?nid=148&sid=109039 KSL News story about CFI]
* [http://www.tfhrc.gov/pubrds/05jan/03.htm U.S. Department of Transportation]
* [http://www.pbworld.com/news_events/publications/network/tools/print_article.asp?referrer=/news_events/publications/network/issue_61/61_02_Jonathan.asp PB CFI Engineering Website]
* [http://www.abmb.com/cfi-testdrive.html ABMB Engineers site includes CFI diagrams and video]