![Greensboro road signs](https://upload.wikimedia.org/wikipedia/commons/e/e9/Greensboro_road_signs.jpg)
A concurrency in a road network is an instance of one physical roadway bearing two or more different
route number
A route (or road) number, designation or abbreviation is an identifying numeric (or alphanumeric) designation assigned by a highway authority to a particular stretch of roadway to distinguish it from other routes and, in many cases, also to indic ...
s. When two roadways share the same
right-of-way
Right of way is the legal right, established by grant from a landowner or long usage (i.e. by prescription), to pass along a specific route through property belonging to another.
A similar ''right of access'' also exists on land held by a gov ...
, it is sometimes called a common section or commons. Other terminology for a concurrency includes overlap, coincidence, duplex (two concurrent routes), triplex (three concurrent routes), multiplex (any number of concurrent routes),
dual routing or triple routing.
Concurrent numbering can become very common in jurisdictions that allow it. Where multiple routes must pass between a single mountain crossing or over a bridge, or through a major city, it is often economically and practically advantageous for them all to be accommodated on a single physical roadway. In some jurisdictions, however, concurrent numbering is avoided by posting only one route number on highway signs; these routes disappear at the start of the concurrency and reappear when it ends. However, any route that becomes unsigned in the middle of the concurrency will still be signed on most maps and road atlases.
Overview
Most concurrencies are simply a combination of at least two route numbers on the same physical roadway. This is often practically advantageous as well as economically advantageous; it may be better for two route numbers to be combined into one along rivers or through mountain valleys. Some countries allow for concurrencies to occur, however, others specifically do not allow it to happen. In those nations which do permit concurrencies, it can become very common. In these countries, there are a variety of concurrences which can occur.
An example of this is the concurrency of
Interstate 70 (I-70) and
I-76
Interstate 76 may refer to:
Interstate Highways in the United States
* Interstate 76 (Colorado–Nebraska)
* Interstate 76 (Ohio–New Jersey), running through Pennsylvania
Video gaming
* ''Interstate '76
''Interstate '76'' is a vehicular ...
on the
Pennsylvania Turnpike
The Pennsylvania Turnpike (Penna Turnpike or PA Turnpike) is a toll highway operated by the Pennsylvania Turnpike Commission (PTC) in the U.S. state of Pennsylvania. A controlled-access highway, it runs for across the state. The turnpike's we ...
in western
Pennsylvania
Pennsylvania (; ( Pennsylvania Dutch: )), officially the Commonwealth of Pennsylvania, is a state spanning the Mid-Atlantic, Northeastern, Appalachian, and Great Lakes regions of the United States. It borders Delaware to its southeast, ...
. I-70 merges with the Pennsylvania Turnpike so the route number can ultimately continue east into Maryland; instead of having a second physical highway built to carry the route, it is combined with the Pennsylvania Turnpike and the I-76 designation.
A triple Interstate concurrency is found in Wisconsin along the section of
I-41
Interstate 41 (I-41) is a north–south Interstate Highway connecting the interchange of I-94 and U.S. Route 41 (US 41), located south of the Wisconsin–Illinois border at the end of the Tri-State Tollway in metropolitan C ...
,
I-43
Interstate 43 (I-43) is a Interstate Highway located entirely within the US state of Wisconsin, connecting I-39/ I-90 in Beloit with Milwaukee and I-41, U.S. Highway 41 (US 41) and US 141 in Green Bay. State Trunk Highwa ...
, and
I-894 in
Milwaukee, Wisconsin
Milwaukee ( ), officially the City of Milwaukee, is both the most populous and most densely populated city in the U.S. state of Wisconsin and the county seat of Milwaukee County, Wisconsin, Milwaukee County. With a population of 577,222 at th ...
. The concurrency of I-41 and I-43 on this roadway is an example of a
wrong-way concurrency
A concurrency in a road network is an instance of one physical roadway bearing two or more different route numbers. When two roadways share the same right-of-way, it is sometimes called a common section or commons. Other terminology for a concurr ...
.
The longest Interstate highway concurrency is
I-80
Interstate 80 (I-80) is an east–west transcontinental freeway that crosses the United States from downtown San Francisco, California, to Teaneck, New Jersey, in the New York metropolitan area. The highway was designated in 1956 as one o ...
and
I-90
Interstate 90 (I-90) is an east–west transcontinental freeway and the longest Interstate Highway in the United States at . It begins in Seattle, Washington, and travels through the Pacific Northwest, Mountain West, Great Plains, Midwest, and ...
for across
Indiana
Indiana () is a U.S. state in the Midwestern United States. It is the 38th-largest by area and the 17th-most populous of the 50 States. Its capital and largest city is Indianapolis. Indiana was admitted to the United States as the 19th s ...
and
Ohio
Ohio () is a state in the Midwestern region of the United States. Of the fifty U.S. states, it is the 34th-largest by area, and with a population of nearly 11.8 million, is the seventh-most populous and tenth-most densely populated. The sta ...
.
There are at least two examples of eight-way concurrencies. The first example is in
Indianapolis
Indianapolis (), colloquially known as Indy, is the state capital and most populous city of the U.S. state of Indiana and the seat of Marion County. According to the U.S. Census Bureau, the consolidated population of Indianapolis and Marion ...
, between exits 46 and 47 of the
I-465 beltway
A ring road (also known as circular road, beltline, beltway, circumferential (high)way, loop, bypass or orbital) is a road or a series of connected roads encircling a town, city, or country. The most common purpose of a ring road is to assist i ...
, where the highway is concurrent with
U.S. Route 31 (US 31),
US 36,
US 40,
US 52,
US 421,
State Road 37 (SR 37), and
SR 67.
Once
I-69
Interstate 69 (I-69) is an Interstate Highway in the United States currently consisting of 10 unconnected segments with an original continuous segment from Indianapolis, Indiana, northeast to the Canadian border in Port Huron, Michigan, at ...
is extended south of Indianapolis, this segment will have a nine-way concurrency. The second example is in
downtown Athens, Georgia, between exits 4 and 8 of
Georgia State Route 10 Loop, where the highway is concurrent with
US 29
U.S. Route 29 (US 29) is a north–south United States highway that runs for from Pensacola, Florida to the western suburbs of Baltimore, Maryland in the Southern United States, connecting the Florida Panhandle to the Baltimore-Washington ...
,
US 78,
US 129,
US 441,
State Route 8 (SR 8),
SR 15, and
SR 422.
Regional examples
North America
![QEW and Hwy 403 Concurrency](https://upload.wikimedia.org/wikipedia/commons/f/f8/QEW_and_Hwy_403_Concurrency.jpg)
In the United States, concurrencies are simply marked by placing signs for both routes on the same or adjacent posts. The federal ''
Manual on Uniform Traffic Control Devices
The ''Manual on Uniform Traffic Control Devices for Streets and Highways'' (usually referred to as the ''Manual on Uniform Traffic Control Devices'', abbreviated MUTCD) is a document issued by the Federal Highway Administration (FHWA) of the Unit ...
'' prescribes that when mounting these adjacent signs together that the numbers will be arranged vertically or horizontally in order of precedence. The order to be used is
Interstate Highway
The Dwight D. Eisenhower National System of Interstate and Defense Highways, commonly known as the Interstate Highway System, is a network of controlled-access highways that forms part of the National Highway System in the United States. Th ...
s,
U.S. Highway
The United States Numbered Highway System (often called U.S. Routes or U.S. Highways) is an integrated network of roads and highways numbered within a nationwide grid in the contiguous United States. As the designation and numbering of these h ...
s,
state highway
A state highway, state road, or state route (and the equivalent provincial highway, provincial road, or provincial route) is usually a road that is either ''numbered'' or ''maintained'' by a sub-national state or province. A road numbered by a ...
s, and finally
county road
A county highway (also county road or county route; usually abbreviated CH or CR) is a road in the United States and in the Canadian province of Ontario that is designated and/or maintained by the County (United States), county highway departme ...
s, and within each class by increasing numerical value.
Several states do not officially have any concurrencies, instead officially ending routes on each side of one. There are several circumstances where unusual concurrencies exist along state borders. One example occurs along the
Oklahoma
Oklahoma (; Choctaw language, Choctaw: ; chr, ᎣᎧᎳᎰᎹ, ''Okalahoma'' ) is a U.S. state, state in the South Central United States, South Central region of the United States, bordered by Texas on the south and west, Kansas on the nor ...
–
Arkansas
Arkansas ( ) is a landlocked state in the South Central United States. It is bordered by Missouri to the north, Tennessee and Mississippi to the east, Louisiana to the south, and Texas and Oklahoma to the west. Its name is from the Osage ...
state line. At the northern end of this border
Oklahoma State Highway 20
State Highway 20 (abbreviated SH-20) is a highway in northeastern Oklahoma. Its eastern terminus is at the corner of Oklahoma, Arkansas, and Missouri near Southwest City, Missouri; its western terminus is at State Highway 18 near Ralston. The ...
runs concurrently with
Arkansas Highway 43
Highway 43 (AR 43, Ark. 43, and Hwy. 43) is a designation for three north–south state highways in Arkansas. One segment of runs from Highway 264 in Siloam Springs north into Delaware County, Oklahoma along Oklahoma S ...
and the two highways run north–south along the boundary.
![ON_400_TCH](https://upload.wikimedia.org/wikipedia/commons/f/f4/ON_400_TCH.jpg)
Concurrencies are also found in Canada.
British Columbia Highway 5 continues east for concurrently with
Highway 1 and
Highway 97, through
Kamloops
Kamloops ( ) is a city in south-central British Columbia, Canada, at the confluence of the South flowing North Thompson River and the West flowing Thompson River, east of Kamloops Lake. It is located in the Thompson-Nicola Regional District, w ...
. This stretch of road, which carries Highway 97 south and Highway 5 north on the same roadway (and vice versa), is the only wrong-way concurrency in British Columbia. Concurrencies are also very common in
Quebec
Quebec ( ; )According to the Canadian government, ''Québec'' (with the acute accent) is the official name in Canadian French and ''Quebec'' (without the accent) is the province's official name in Canadian English is one of the thirtee ...
. Most notably, the
Samuel-de-Champlain Bridge features a concurrency with three Autoroutes:
A-10
The Fairchild Republic A-10 Thunderbolt II is a single-seat, twin-turbofan, straight-wing, subsonic attack aircraft developed by Fairchild Republic for the United States Air Force (USAF). In service since 1976, it is named for the Republi ...
,
A-15, and
A-20. Another example is
A-55, which runs concurrently with A-10, A-20, and
A-40, all of which are major highways.
In
Ontario
Ontario ( ; ) is one of the thirteen provinces and territories of Canada.Ontario is located in the geographic eastern half of Canada, but it has historically and politically been considered to be part of Central Canada. Located in Central Ca ...
, the
Queen Elizabeth Way
The Queen Elizabeth Way (QEW) is a 400-series highway in the Canadian province of Ontario linking Toronto with the Niagara Peninsula and Buffalo, New York. The freeway begins at the Peace Bridge in Fort Erie and travels around the western ...
and
Highway 403 run concurrently between
Burlington
Burlington may refer to:
Places Canada Geography
* Burlington, Newfoundland and Labrador
* Burlington, Nova Scotia
* Burlington, Ontario, the most populous city with the name "Burlington"
* Burlington, Prince Edward Island
* Burlington Bay, no ...
and
Oakville, forming the province's only concurrency between two
400-series highways.
The concurrency was not in the original plan which intended for both the QEW and Highway 403 to run parallel to each other, as the Hamilton–Brantford and Mississauga sections of Highway 403 were initially planned to be linked up along a corridor (later planned to be
tolled) now occupied by
Highway 407. To avoid forcing drivers to pay tolls to use a section of a continuous Highway 403, the new link was designated as a western extension of the tolled Highway 407, with the Mississauga section of Highway 403 planned to be renumbered as Highway 410. The renumbering to 410 never came to pass, and consequently Highway 403 was signed concurrently along the Queen Elizabeth Way in 2002, remedying the discontinuity. Nonetheless, many surface street signs referring to that section of freeway with the QEW/Highway 403 concurrency still only use the highway's original designation of QEW, although the MTO has updated route markers on the QEW to reflect the concurrency.
At the national level, the
Trans-Canada Highway
The Trans-Canada Highway ( French: ; abbreviated as the TCH or T-Can) is a transcontinental federal–provincial highway system that travels through all ten provinces of Canada, from the Pacific Ocean on the west coast to the Atlantic Ocean o ...
, which does not bear a uniform number in the eastern provinces, follows various provincial highways. In the
Atlantic Provinces
Atlantic Canada, also called the Atlantic provinces (french: provinces de l'Atlantique), is the region of Eastern Canada comprising the provinces located on the Atlantic coast, excluding Quebec. The four provinces are New Brunswick, Newfoundlan ...
the main designated TCH route either follows a single numbered route across each province (an exception being the switching of the designation between
Nova Scotia Highways 104 and
105), or has branches that are signed exclusively as TCH routes. In Ontario and Quebec, The TCH follows a series of provincial highways, and also has branches that follow sections of others that have concurrencies with it, signed with TCH shields alongside the provincial number.
Europe
![Labský most, značky silnic](https://upload.wikimedia.org/wikipedia/commons/7/7d/Labsk%C3%BD_most%2C_zna%C4%8Dky_silnic.jpg)
In the United Kingdom, routes do not run concurrently with others. Where this would normally occur, the roadway takes the number of only one of the routes (usually, but not always, the most important route), while the other routes are considered to have a gap and are signed in brackets (the equivalent of "to" signs in North America). An example is the meeting of the
M60 and the
M62 northwest of
Manchester
Manchester () is a city in Greater Manchester, England. It had a population of 552,000 in 2021. It is bordered by the Cheshire Plain to the south, the Pennines to the north and east, and the neighbouring city of Salford to the west. The t ...
: the motorways coincide for the between junctions 12 and 18 but the motorway between those points is only designated as the M60 (although in this case the same junction numbers would also apply to the M62).
European route
The international E-road network is a numbering system for roads in Europe developed by the United Nations Economic Commission for Europe (UNECE). The network is numbered from E1 up and its roads cross national borders. It also reaches Centr ...
numbers as designated by
UNECE
The United Nations Economic Commission for Europe (ECE or UNECE) is one of the five regional commissions under the jurisdiction of the United Nations Economic and Social Council. It was established in order to promote economic cooperation and i ...
may have concurrencies (for instance
E15 and
E30 around
Greater London
Greater may refer to:
*Greatness, the state of being great
*Greater than, in inequality (mathematics), inequality
*Greater (film), ''Greater'' (film), a 2016 American film
*Greater (flamingo), the oldest flamingo on record
*Greater (song), "Greate ...
), but since the E-route numbers are unsigned and unused in the UK, the existence of these concurrencies is purely theoretical.
In Sweden and Denmark, the most important highways use only the European route numbers that have cardinal directions. In Sweden the
European route E6 and
E20 run concurrently for . In Denmark the
E47 and
E55 run concurrently for . There are more shorter concurrencies. There are two stretches in Sweden and Denmark where three European routes run concurrently; these are E6, E20 and
E22 in Sweden, and E20, E47, and E55 in Denmark. Along all these concurrencies, all route numbers are posted with signs.
In the Czech Republic, the European route numbers are only additional, and they are always concurrent with the state route numbering, usually highways or first-class roads. In the state numbering system, concurrences exist only in first-class and second-class roads; third class roads do not have them. The local term for such concurrences is (from the French word ). In the road register, one of the roads is considered the main ("source") road and the others as the ''péaging'' (guest) roads. The official road map enables a maximum of five concurrent routes of the intrastate numbering system. Cycling routes and hiking routes are often concurrent.
The Middle East
In Israel, two
freeway
A controlled-access highway is a type of highway that has been designed for high-speed vehicular traffic, with all traffic flow—ingress and egress—regulated. Common English terms are freeway, motorway and expressway. Other similar terms ...
s, the
Trans-Israel Highway #REDIRECT Highway 6 (Israel)
Yitzhak Rabin Highway he, כביש יצחק רבין, Kvish Yitzḥak Rabin, link=no
, length_km = 204
, direction_a = South
, map =
, map_custom = yes
, terminus_a = Shoket (Shoket Interchange)
, cities = Be'er ...
(Highway 6), and
Highway 1 run concurrently just east of
Ben Shemen Interchange
Ben Shemen Interchange ( he, מחלף בן שמן) is a major freeway interchange complex in central Israel, connecting Highway 1, Highway 6, Route 443 and Route 444, as well as several local roads. The interchange is located near moshav Be ...
. The concurrency is officially designated "
Daniel Interchange
Daniel Interchange is a key freeway interchange in the Central District of Israel, located west of its namesake, the village of Kfar Daniel and just south of Ben Shemen Interchange. The interchange takes the form of a 1.5 kilometer long road c ...
", providing half of the possible interchange directions. It is a segment consisting of eight lanes providing high-speed access between the two highways. Access from Highway 1 west to Highway 6 south and Highway 6 north to Highway 1 east is provided via
Route 431, while access between Highway 1 east to Highway 6 north and Highway 6 south to Highway 1 west are provided at Ben Shemen Interchange. The other movements are provided through the concurrency.
Wrong-way concurrencies
![NB77SB81](https://upload.wikimedia.org/wikipedia/commons/6/6c/NB77SB81.JPG)
Since highways in the United States and Canada are usually signed with assigned
cardinal direction
The four cardinal directions, or cardinal points, are the four main compass directions: north, east, south, and west, commonly denoted by their initials N, E, S, and W respectively. Relative to north, the directions east, south, and west are at ...
s based on their primary orientation, it is possible for a stretch of roadway shared between two highways to be signed with conflicting, even opposite, cardinal directions in a wrong-way concurrency. For example, near
Wytheville, Virginia
Wytheville is a town in, and the county seat of, Wythe County, in southwestern Virginia, United States. It is named after George Wythe, a signer of the United States Declaration of Independence, and mentor to Thomas Jefferson. Wytheville's populat ...
, there is a concurrency between
Interstate 77
Interstate 77 (I-77) is a north–south Interstate Highway in the eastern United States. It traverses diverse terrain, from the mountainous state of West Virginia to the rolling farmlands of North Carolina and Ohio. It largely supplants the ...
(which runs primarily north–south, as it is signed) and
Interstate 81
Interstate 81 (I-81) is a north–south (physically northeast–southwest) Interstate Highway in the eastern part of the United States. Its southern terminus is at I-40 in Dandridge, Tennessee; its northern terminus is on Wellesley Island ...
(which runs primarily northeast–southwest, but is also signed north–south). Because of the way they intersect, the section of Interstate where they overlap has the two roads signed for opposite directions, leading to the town's nickname of "Which-Way-Ville". One might simultaneously be on I-77 northbound and I-81 southbound, while actually traveling due westbound.
An unusual example of a three-directional concurrency occurs southeast of
Rhinelander, Wisconsin
Rhinelander is a city in and the county seat of Oneida County, Wisconsin, Oneida County, Wisconsin, United States. The population was 8,285 at the 2020 United States Census, 2020 census.
History
The area that eventually became the city of Rhine ...
, where
US 8 westbound (the actual compass direction) converges with southbound
Wisconsin Highway 17
State Trunk Highway 17 (often called Highway 17, STH-17 or WIS 17) is a state highway in the U.S. state of Wisconsin. The highway is a secondary route in northeastern Wisconsin that directly connects Rhinelander, Eagle River and the central and ...
and northbound
Wisconsin Highway 47
State Trunk Highway 47 (often called Highway 47, STH-47 or WIS 47) is a state highway in the northeastern and northern parts of the US state of Wisconsin that runs in a diagonal northwest–southeast from Menasha to Manitowish.
Route descript ...
.
Effect on exit numbers
Often when two routes with
exit number
An exit number is a number assigned to a road junction, usually an exit from a freeway. It is usually marked on the same sign as the destinations of the exit. In some countries, such as the United States, it is also marked on a sign in the go ...
s overlap, one of the routes has its exit numbers dominate over the other and can sometimes result in having two exits of the same number, albeit far from each other along the same highway. An example of this is from the concurrency of
I-94 and
US 127 near
Jackson
Jackson may refer to:
People and fictional characters
* Jackson (name), including a list of people and fictional characters with the surname or given name
Places
Australia
* Jackson, Queensland, a town in the Maranoa Region
* Jackson North, Qu ...
, Michigan. The concurrent section of freeway has an exit with
M-106, which is numbered exit 139 using I-94's mileage-based numbers. US 127 also has another exit 139 with the southern end of the
US 127 business loop in
Mount Pleasant, Michigan. (US 127's
mile marker
A milestone is a numbered marker placed on a route such as a road, railway line, canal or boundary. They can indicate the distance to towns, cities, and other places or landmarks; or they can give their position on the route relative to s ...
s in Michigan reflect the cumulative distance north of the Ohio state line; the numbers resume north of the I-94 overlap and reflect the distance accumulated on that concurrency.)
However, there are also instances where the dominant exit number range is far more than the secondary route's highest exit number, for example the
concurrency of I-75 and I-85 in
Atlanta, Georgia
Atlanta ( ) is the capital and most populous city of the U.S. state of Georgia. It is the seat of Fulton County, the most populous county in Georgia, but its territory falls in both Fulton and DeKalb counties. With a population of 498,715 ...
— where I-75 is dominant — the exit numbers range from 242 to 251, while I-85's highest independent
mile marker
A milestone is a numbered marker placed on a route such as a road, railway line, canal or boundary. They can indicate the distance to towns, cities, and other places or landmarks; or they can give their position on the route relative to s ...
in
Georgia
Georgia most commonly refers to:
* Georgia (country), a country in the Caucasus region of Eurasia
* Georgia (U.S. state), a state in the Southeast United States
Georgia may also refer to:
Places
Historical states and entities
* Related to the ...
is 179.
Consolidation plans
![NJ guide sign](https://upload.wikimedia.org/wikipedia/commons/9/9f/NJ_guide_sign.jpg)
Some brief concurrencies in the past have been eliminated by reassigning the designations along the roadways. This can involve scaling back the terminus of one designation to the end of a concurrent section. At the same time, there could be an extension of another highway designation that is used to replace the newly shortened designation with another one.
Between states,
US 27 in Michigan previously ran concurrently with
I-69
Interstate 69 (I-69) is an Interstate Highway in the United States currently consisting of 10 unconnected segments with an original continuous segment from Indianapolis, Indiana, northeast to the Canadian border in Port Huron, Michigan, at ...
from the Michigan–Indiana state line to the
Lansing, Michigan
Lansing () is the capital of the U.S. state of Michigan. It is mostly in Ingham County, although portions of the city extend west into Eaton County and north into Clinton County. The 2020 census placed the city's population at 112,644, making ...
, area. From there it turned northwards to its terminus at
Grayling. In 1999, the
Michigan
Michigan () is a state in the Great Lakes region of the upper Midwestern United States. With a population of nearly 10.12 million and an area of nearly , Michigan is the 10th-largest state by population, the 11th-largest by area, and the ...
and
Indiana
Indiana () is a U.S. state in the Midwestern United States. It is the 38th-largest by area and the 17th-most populous of the 50 States. Its capital and largest city is Indianapolis. Indiana was admitted to the United States as the 19th s ...
departments of transportation petitioned the
for permission to truncate US 27 at
Fort Wayne, Indiana
Fort Wayne is a city in and the county seat of Allen County, Indiana, United States. Located in northeastern Indiana, the city is west of the Ohio border and south of the Michigan border. The city's population was 263,886 as of the 2020 Censu ...
.
In 2002, Michigan removed the US 27 designation from I-69 and extended the
US 127 designation from Lansing to Grayling.
MDOT's stated reason for the modification was to "reduce confusion along the US 27/US 127 corridor".
[ After US 27's signage was removed, the highway north of the Lansing area was renumbered US 127, and the US 27 designation was removed from I-69.]
Some consolidation schemes involve the use of incorporating two single-digit numbers onto one marker, as along the US 1/9 concurrency in northern New Jersey
New Jersey is a state in the Mid-Atlantic and Northeastern regions of the United States. It is bordered on the north and east by the state of New York; on the east, southeast, and south by the Atlantic Ocean; on the west by the Delaware ...
. In the mid-20th century, California
California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...
had numerous concurrencies, but the California Legislature
The California State Legislature is a bicameral state legislature consisting of a lower house, the California State Assembly, with 80 members; and an upper house, the California State Senate, with 40 members. Both houses of the Legisla ...
removed most of them in a comprehensive reform of highway numbering in 1964.
See also
*
*
Notes
References
External links
{{DEFAULTSORT:Concurrency (Road)
Road transport