A continuous flow intersection (CFI), also called a crossover displaced left-turn (XDL or DLT), is an alternative design for an at-grade road junction. Vehicles attempting to turn across the opposing direction of traffic (left in right-hand drive jurisdictions; right in left-hand drive jurisdictions) cross before they enter the intersection. No left turn signal in the intersection is then necessary. Instead, vehicles traveling in both directions can proceed, including through vehicles and those turning right or left, when a generic traffic signal/stop sign permits.
Its design also is promoted as part of the Federal Highway Administration's Every Day Counts initiative which started in 2011.[1]
A fly-over designed CFI interchange (separated grade) was invented by Francisco Mier. An intersection (at-grade) variant followed. Over 40 have been implemented since 2000. Mier patented his design and required a fee to obtain a license to the design.[2] The patent expired in the United States on 15 October 2003.[3]
This general configuration has appeared in different versions in various places, with the implementation of channelization in the United States since the 1950s, such as the Telegraph Road section of U.S. Route 24 in Michigan at Plymouth Road in Redford Charter Township, Michigan.[4]
| Australia | Queensland | Gold Coast | Salerno Street, Bundall Road and Ashmore Road | December 2017 | ||
| Victoria | Melbourne | Hoddle Street | 2017 | [5] | ||
| New South Wales | Moore Park | Intersection of Anzac Parade, Alison Road and Dacey Avenue | 2017 | |||
| Canada | Prince Edward Island | Charlottetown | Charlottetown Perimeter Highway and St. Peters Road | November 29, 2020 | 46.268692°N 63.114001°W | [6] |
| China | Guangdong | Shenzhen | Caitian Road and Fuhua | October 7, 2017 | ||
| Germany | Hamburg | Breitenfelder Straße (Bundesstraße 5) and Tarpenbekstraße (Bundesstraße 433) | 53.590267°N 9.982989°E | |||
| Mexico | Coahuila | Saltillo | Paseo de la Reforma and Periférico und Luis Echeverría | 25.42739°N 100.969859°W | ||
| Chihuahua | Juárez Municipality | Manuel Gómez Morin Bermúdez aund De La Industria | 31.70368°N 106.401998°W | |||
| Nuevo León | Guadalupe Island | Between Chapultepec, Puesta del Sol and Av Eloy Cavazos | 25.661967°N 100.258747°W | |||
| United Kingdom | Swindon | A4311 road, Cricklade Road and Thamesdown Drive | 2003 | 51.601158562°N 1.7812545°W | ||
| United States | New Jersey | Camden | New Jersey Route 168 at US Route 130 | |||
| Audubon, New Jersey | New Jersey Route 168 at Nicholson Road | 39.894161°N 75.091435°W | ||||
| New York | Shirley | 1996 | 40.826443°N 72.881042°W | |||
| Maryland | Accokeek | Routes 210 and 228 | 2000 | 38.664126°N 77.016928°W | ||
| Laurel | MD 200 and US 1 | November 7, 2014 | 39.065800°N 76.881176°W | |||
| Louisiana | Baton Rouge | Airline Highway and Siegen Lane | March 2006 | 30.398914°N 91.054119°W | ||
| Lafayette | US 167 (Johnston St.) and Camellia Boulevard | 2010 | 30.193744°N 92.058622°W | |||
| Utah | Taylorsville | Bangerter Highway and 5400 South (SR-173) | 40.652993°N 111.981339°W | No longer exists[7] | ||
| West Valley City | Bangerter Highway and 4700 South | 40.667596°N 111.981567°W | No longer exists | |||
| Bangerter Highway and 4100 South | 40.682132°N 111.981626°W | |||||
| Bangerter Highway and 3500 South (SR-171) | September 2007 | 40.696629°N 111.980869°W | ||||
| Bangerter Highway and 3100 South | 40.703918°N 111.980076°W | |||||
| Bangerter Highway and 6200 South (Bennion Boulevard) | 40.638581°N 111.976637°W | No longer exists | ||||
| 5400 S (SR-173) and Redwood Road | 40.653176°N 111.938802°W | |||||
| 6200 South (Bennion Boulevard) and Redwood Road | 40.638574°N 111.938824°W | [8] | ||||
| Riverton | Bangerter Highway and 13400 South | 40.507803°N 111.982747°W | ||||
| West Jordan | Bangerter Highway and 7000 South | 40.623983°N 111.976422°W | No longer exists | |||
| Orem | University Parkway and Sandhill Road | May 22, 2012 | 40.275014°N 111.713445°W | [9] | ||
| Mississippi | Natchez | US 61 and Junkin Drive | January 2010 | 31.528599°N 91.389213°W | ||
| Oxford | Mississippi Highway 6 and West Jackson Avenue | April 29, 2015 | ||||
| Colorado | Loveland | US 34 (Eisenhower Boulevard) and Madison Avenue | 40.407365°N 105.058764°W | [10] | ||
| Durango | US 160 and US 550 | 37.268540°N 107.884992°W | [11] | |||
| Colorado Springs | Woodmen Road and Union Boulevard | December 2017 | 38.933079°N 104.775202°W | [12] | ||
| North Carolina | Charlotte | NC 16 to Mount Holly-Huntersville Road | October 18, 2019 | |||
| Texas | Cedar Park | RM 1431 and Ronald Reagan Boulevard/Parmer Lane | August 2, 2016 | 30.534659°N 97.782645°W | ||
| San Marcos | Loop 82 (Aquarena Springs Drive) and I-35's southbound-to-northbound Texas U-turn | 29.893048°N 97.913367°W | ||||
| State Highway 80 (Hopkins Street), I-35's frontage roads and I-35's Texas U-turns | 29.882639°N 97.921915°W | |||||
| San Antonio | Bandera Road and Loop 1604 | April 28, 2019 | 29.553655°N 98.667302°W | [13] | ||
| Georgia | Dawsonville | SR 400 and SR 53 | May 15, 2017 | 34.363385°N 84.036474°W | [14] | |
| Indiana | Indianapolis | US 31 and Thompson Road | October 8, 2022 | 39.693213°N 86.148812°W | [15] | |
| Warrick County | IN 66 and Epworth Road | August 20, 2024 | 37.976790°N 87.441226°W | [16] | ||
| Ohio | Anderson Township | Beechmont Avenue (State Route 125) and Five Mile Road | May 19, 2017 | 39°4′22″N 84°21′7″W | [17] | |
| Miami Township (Montgomery County) | SR 741 and Miamisburg-Springboro Road/Austin Boulevard | 2009 | 39.596709°N 84.229029°W | [18] | ||
| Virginia | Norfolk | Military Highway onto Northampton Boulevard and Princess Anne Road | July 28, 2018 | 36.874804°N 76.210739°W | ||
| Florida | Fort Myers | State Road 82 to Daniels Parkway (west) and Gunnery Road (east) | July 9, 2019 | 26.581661°N 81.713761°W | [19] | |
| Kansas | Olathe | Old 56 Highway to Lone Elm Road | June 2021 | |||
| Missouri | Fenton | Highway 30 and Summit Drive/Gravois Bluffs Boulevard | October 2007 | 38.504276°N 90.456995°W | [20] |
Part of the delay at a typical high-volume right-hand traffic intersection is to accommodate left-turns; through-traffic must wait for the traffic turning left because it crosses the path of the through traffic. The continuous flow intersection moves the left-turn conflict out of the intersection and synchronizes it with the signal cycle of the intersecting road.
In the adjacent diagram, while the left/right traffic flows through the main intersection, the left-turn traffic crosses to the opposite side of the oncoming traffic a few hundred feet away. Doing this removes the crossing conflict. When the north/south through traffic is allowed through the main intersection, the north/south left-turn lanes are also allowed through the intersections as their paths are no longer crossing. All traffic flow is controlled by traffic signals as at a regular intersection.
The Louisiana DOTD article on the Baton Rouge CFI includes a particularly informative diagram of that intersection.[21]
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 the speed differential, a known cause of accidents, though conflicts could be reduced through the provision of an adequate acceleration lane and merge area. The Accokeek, MD CFI also has notable inequalities in traffic flow depending upon the direction of travel.
This type of intersection can require a significant amount of right-of-way to implement (dependent upon the configuration), which is why the technique is not frequently used in urban areas. However, the amount of right-of-way 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.
The redesign of the Redwood Road/6200 South intersection in Taylorsville, Utah cut emissions of carbon dioxide by 19 tons (17 tonnes) per year.[22] Compared to the previous design, the redesign of the Bangerter Highway/3500 South intersection saves minutes of travel time per vehicle and 800000abbr=offNaNabbr=off of fuel per year, and has 60% fewer accidents nearby; it also cost $20 million to $40 million less in construction costs than a grade-separated alternative.[23]
A parallel-flow intersection (PFI) is a variant similar to the CFI, patented in 2006.[24] It arranges the left-turning traffic in a different manner; it is not displaced, instead turning left closer to the intersection onto a parallel roadway, to the left of oncoming traffic.[25] This was first used in New Jersey at the junction of New Jersey Route 168 and US Highway 130, between Haddon Township and Camden (39.9041°N -75.0958°W).
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.