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2+1 road is a specific category of three-lane
road A road is a thoroughfare used primarily for movement of traffic. Roads differ from streets, whose primary use is local access. They also differ from stroads, which combine the features of streets and roads. Most modern roads are paved. Th ...
, consisting of two lanes in one direction and one lane in the other, alternating every few kilometres, and usually separated with a steel
cable barrier A cable barrier, sometimes referred to as guard cable or wire rope safety barrier (WRSB), is a type of roadside or median safety traffic barrier/guard rail. It consists of steel wire ropes mounted on weak posts. As is the case with any roadside ...
. The second lane allows faster-moving traffic to overtake slower vehicles at regular intervals. Traditional roads of at least width can be converted to 2+1 roads and reach near-
motorway 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 ...
safety levels at a much lower cost than an actual conversion to motorway or dual carriageway. Sometimes, during freeway reconstruction, a barrier transfer machine will be used on one half of the freeway while the other is being reconstructed.


By country


Canada

In 2023 the province of
Ontario Ontario is the southernmost Provinces and territories of Canada, province of Canada. Located in Central Canada, Ontario is the Population of Canada by province and territory, country's most populous province. As of the 2021 Canadian census, it ...
announced an assessment and design contract was awarded to convert Highway 11 north of North Bay to a 2+1 design; once the design has been finalized there will be a tender to build it.


Estonia

The construction of 2+1 roads in Estonia first started in autumn 2016, when a contract for a reconstruction of a 9 kilometre section of the national road 4 between
Ääsmäe Ääsmäe is a village in Saue Parish, Harju County in northern Estonia. Ääsmäe manor The manor in Ääsmäe traces its origins to 1574, when king John III of Sweden presented the estate as a gift to his secretary Johann Berends. The present ...
and Kohatu into a 2+1 road was signed. The road is being reconstructed as a 2+1 road, equipped with barriers along the entire length. Also there are several sections of the national road 2 between
Põltsamaa Põltsamaa is a town in Põltsamaa Parish, Jõgeva County, in central Estonia. The town stands on the Põltsamaa River, and it features a Põltsamaa Castle, 13th-century castle. History During the German occupation in World War II, a subcamp of ...
and
Tartu Tartu is the second largest city in Estonia after Tallinn. Tartu has a population of 97,759 (as of 2024). It is southeast of Tallinn and 245 kilometres (152 miles) northeast of Riga, Latvia. Tartu lies on the Emajõgi river, which connects the ...
planned for a conversion into 2+1 road. The first of them ( Annikvere- Neanurme) was opened in November 2017. The speed limits are during summer and during winter.


Finland

The first 2+1 road in Finland was opened in 1991 on
Finnish national road 4 Finnish national road 4 ( or ; or ; also known as Lahti Highway (; ) in the Helsinki Metropolitan Area) is a highway in Finland. It is the main route from Helsinki to Northern Finland and a major road link in the country. It runs from Erottaja ...
between
Järvenpää Järvenpää (; , ; ) is a town in Finland, located in the southern interior of the country. Järvenpää is situated in the centre of the Uusimaa region in the immediate vicinity of Lake Tuusula. The population of Järvenpää is approximately ...
and
Mäntsälä Mäntsälä () is a municipality in the province of Southern Finland, and is part of the Uusimaa region. It has a population of () and covers an area of of which is water. The population density is . The municipality is unilingually Finni ...
, which later was upgraded to a motorway. Since then, numerous 2+1 roads have been built as part of the national road network. They resemble motorways in that they are typically, although not always,
limited-access road A limited-access road, known by various terms worldwide, including limited-access highway, partial controlled-access highway, and expressway, is a highway or arterial road for high-speed traffic which has many or most characteristics of a contro ...
s and have no at-grade interchanges. In the mid-1990s, 2+1 roads with traffic separators were introduced; these are effective in preventing head-on collisions, and approaching the safety of motorways. In 2006, there were 440 km of 2+1 roads, e.g. along road 3 and road 4. However, they weren't that much of a panacea: interchanges made the roads much more expensive than planned and confusing to drivers. Thus, new construction halted and only 2+2 roads with traffic separators were built. These are however more expensive and require more widening of the road.


Germany

The "2+1-System" refers to expressways with three lanes on a single carriageway where bypassing on the lane of the opposite direction is prohibited so that speed restriction is not required to increase safety. These expressways are grade-separated with a design speed of and the side of two lanes (allowing to bypass lower speed vehicles) alternates about every 1.5 to 2 kilometres. In hilly parts, the uphill direction is usually the one with two lanes to allow overtaking of heavy, slow vehicles. In many cases, there is no median barrier or it consists of concrete blocks – additional safety measures are mostly needed near the end of the two lane section where some motorists tend to pull in very late so that a longer no-traffic section needs to be inserted on the middle lane. After some good experiences with test roads the system has been used often in places where the amount of traffic does not justify construction of a dual carriageway expressway but remote rural areas should be connected to major towns with a high speed road. Existing examples are B 1, B 4 near Uelzen, B 16, B 20, B 31n near Stockach (), B 33, B 54, B 56n, B 67 between Bocholt-West and Borken, B 72, B 210, B 300, B 473 between Bocholt and Hamminkeln, B 482 and parts of the A 98.


Israel

In
Israel Israel, officially the State of Israel, is a country in West Asia. It Borders of Israel, shares borders with Lebanon to the north, Syria to the north-east, Jordan to the east, Egypt to the south-west, and the Mediterranean Sea to the west. Isr ...
, route 437 is a 2+1 from Hizme Junction to Adam Junction. The road descends before ascending, and whichever direction is uphill is the one with two lanes.


Ireland

In the
Republic of Ireland Ireland ( ), also known as the Republic of Ireland (), is a country in Northwestern Europe, north-western Europe consisting of 26 of the 32 Counties of Ireland, counties of the island of Ireland, with a population of about 5.4 million. ...
, a 2+1 road was tried on a short section of the N20 near Mallow,
County Cork County Cork () is the largest and the southernmost Counties of Ireland, county of Republic of Ireland, Ireland, named after the city of Cork (city), Cork, the state's second-largest city. It is in the Provinces of Ireland, province of Munster ...
and the N2 near Castleblayney,
County Monaghan County Monaghan ( ; ) is a Counties of Ireland, county in Ireland. It is in the Provinces of Ireland, province of Ulster and is part of Border Region, Border strategic planning area of the Northern and Western Region. It is named after the town ...
. Following the pilot, the
National Roads Authority The National Roads Authority (NRA) () is a state body in Ireland, responsible for the national road network. The NRA was established as part of the Roads Act 1993 and commenced operations on 23 December 1993 in accordance with S.I. 407 of 1993 ...
announced in July 2007 that 2+1 roads were unsuitable and that new lower capacity trunk routes would instead be built as 2+2 roads (officially known as "Type 2 Dual Carriageways") – at grade dual-carriageways with a narrow median and no hard shoulder.


Lithuania

The first rural 2+1 road section finished in Lithuania was a short road section of A11 between
Šiauliai Šiauliai ( ; ) is a city in northern Lithuania, the List of cities in Lithuania, country's fourth largest city and the List of cities in the Baltic states by population, sixth largest city in the Baltic States, with a population of 112 581 in 202 ...
and the junction with the A18 road (
Šiauliai Šiauliai ( ; ) is a city in northern Lithuania, the List of cities in Lithuania, country's fourth largest city and the List of cities in the Baltic states by population, sixth largest city in the Baltic States, with a population of 112 581 in 202 ...
Bypass). It was opened in late 2017. All 1+1 sections of Via Baltica north of
Kaunas Kaunas (; ) is the second-largest city in Lithuania after Vilnius, the fourth largest List of cities in the Baltic states by population, city in the Baltic States and an important centre of Lithuanian economic, academic, and cultural life. Kaun ...
up to the
Latvia Latvia, officially the Republic of Latvia, is a country in the Baltic region of Northern Europe. It is one of the three Baltic states, along with Estonia to the north and Lithuania to the south. It borders Russia to the east and Belarus to t ...
n border are planned to be converted to 2+1 by 2035. The first section, the A17 road or
Panevėžys Panevėžys () is the fifth-largest List of cities in Lithuania, city in Lithuania and the List of cities in the Baltic states by population, eighth-most-populous city in the Baltic States. it occupies with 89,100 inhabitants. As defined by Eu ...
Bypass was constructed in 2019. Work took place in stages. The first section between junctions with the A8 and the A9 was finished in summer 2018. The remaining section up to the A10 road was completed in 2019. All planned 2+1 sections will be equipped with barriers.


New Zealand

In New Zealand, there are few 2+1 roads, although regular isolated 'passing lanes' exist frequently throughout the country, mainly in heavily trafficked areas and on hills. A trial of a 2+1 road with a wire-rope median barrier was undertaken on SH1 between Longswamp and Rangiriri south of Auckland, and there are plans to introduce more 2+1 roads. NZ research also investigated the design and operational effects of 2+1 roads to establish the most appropriate configurations for the country.


Portugal

In Portugal, there are plenty of 2+1 roads. Almost every national road in the country has a 2+1 profile, but the biggest part is located in the north because of the hills (for example, in Beira Baixa, or
Viseu Viseu () is a city and municipality in the Centro Region of Portugal and the capital of the Viseu District, district of the same name, with a population of 100,105 inhabitants in the entire municipality, and center of the Viseu Dão Lafões Interm ...
). One example of this is the N2 road, which goes from Faro (
Algarve The Algarve (, , ) is the southernmost NUTS statistical regions of Portugal, NUTS II region of continental Portugal. It has an area of with 467,495 permanent inhabitants and incorporates 16 municipalities (concelho, ''concelhos'' or ''município ...
) to Chaves. Also, this type of road isn't frequently used on parts of roads that have a village near, except in the
Lisbon District Lisbon District () is a district located along the western coast of Portugal. The district capital is the city of Lisbon, which is also the national capital. From its creation until 1926, it included the area of the current Setúbal District. ...
where most of them have that profile. In Portugal, there are 4 (major) types of roads: a national road (N) which sometimes contains the 2+1 profile, a complementary route (IC), which always contains the 2+1 profile, except inside villages, a principal route (IP) which either contains the 2+1 profile (with the IC profile) or the 2+2 profile (with the A profile) and a highway (A) which has its own profiles, like 2+2, 3+3 or 4+4.


Romania

The 2+1 road format in Romania often refers to sections, usually on steep inclines, where there is another lane, designed to be used by slow vehicles to avoid congestion when going uphill. The first 2+1 "alternative" road opened between Lazaret and Turnul Spart in 2018 on the Olt Valley section of the DN7. This section lacks cable barriers, but provisions have been made to install one, if needed. The next 2+1 road section to open will be between Sinești and Movilița on the DN2. The DN2 is currently configured as a 13 m wide road with emergency lanes, in the same style as 13 m wide roads in Sweden, however, drivers improperly use the emergency lanes, leading to the current high number of crashes. Once the roadworks will be completed, the 2+1 road is supposed to reduce the number of crashes, but it will lack the essential cable barrier. This is because the only cable barrier installed in Romania, at Afumați on the same DN2 was damaged because the lanes were too close to it and a truck hit it, but instead, the Romanian Roads Administration (CNADNR) blamed the "unsafety" of the barrier.


Russia

Some federal roads use the 2+1 design. The length of overtaking sections is 400 to 3,000 metres. Unlike in Western Europe, the majority of Russian 2+1 roads are not equipped with barriers and have a mediocre quality of the road surface. The most well-known example of a 2+1 is the M-10 road section between
Tver Tver (, ) is a types of inhabited localities in Russia, city and the administrative centre of Tver Oblast, Russia. It is situated at the confluence of the Volga and Tvertsa rivers. Tver is located northwest of Moscow. Population: The city is ...
and
Novgorod Oblast Novgorod Oblast () is a federal subject of Russia (an oblast). Its administrative center is the city of Veliky Novgorod. Some of the oldest Russian cities, including Veliky Novgorod and Staraya Russa, are located in the oblast. The historic m ...
. Other than that, the 2+1 roads are particularly popular in
Krasnodar Krai Krasnodar Krai (, ) is a federal subjects of Russia, federal subject of Russia (a krai), located in the North Caucasus region in Southern Russia and is administratively a part of the Southern Federal District. Its administrative center is the t ...
and
Sakhalin Oblast Sakhalin Oblast ( rus, Сахали́нская о́бласть, r=Sakhalinskaya oblastʹ, p=səxɐˈlʲinskəjə ˈobləsʲtʲ) is a federal subject of Russia (an oblast) comprising the island of Sakhalin and the Kuril Islands in the Russian ...
.


Sweden

In Sweden, many roads have been built, especially in the period 1955–1980. These have two lanes, and two shoulders, in the beginning planned as emergency strip, due to the relative unreliability of cars of that period. Around 1990, the idea emerged to build fences in the middle of them and to have 2+1 lanes. This was thought to be a cheap way of increasing traffic safety since these roads had a bad safety record of many head-on collisions at high speeds. Some people were, for example, overtaking against meeting traffic assuming meeting cars would go to the side. The roads are a little narrow for 3 lanes, but trials were carried out on a few roads. It turned out that not only did safety improve, but it was also easier to overtake than before as the 2-lane sections provide safe overtaking opportunities. After the year 2000, more than of roads in Sweden have been converted from wide ordinary roads into 2+1-road, all with barriers. Until around 2005, the roads had the original speed limit in use on most highways. As a result of this, many people drove at 90 km/h at 1-lane parts but at 2-lane parts, this being the speed limit on motorways. The speed limit has now been changed to with a notably smoother traffic flow. There is a problem that some people want to overtake as many slow cars as possible in the two-lane sections, sometimes with small margins at the end of the section.


United Kingdom

In the UK, 2+1 roads are known as 'Wide single 2+1 roads'. According to the Design Manual for Roads and Bridges, they should only be used on rural all-purpose single carriageways. The overtaking lane sections can be between 800 metres and 1500 metres. This is because this length allows for cars to overtake, but does not cause frustration for drivers on single-lane sections. It is recommended to use hatching with double solid lines to separate traffic flows to stop single-lane traffic from using the oncoming overtaking lane. 2+1 roads can also be used for climbing lanes, to allow slower vehicles to be overtaken by other vehicles when travelling uphill on a single carriageway. They should be used where the road is longer than 500 metres at a gradient of 2%.


United States

The United States has 2+1 roads in states such as
California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...
,
New Hampshire New Hampshire ( ) is a U.S. state, state in the New England region of the Northeastern United States. It borders Massachusetts to the south, Vermont to the west, Maine and the Gulf of Maine to the east, and the Canadian province of Quebec t ...
, Arkansas, and
Missouri Missouri (''see #Etymology and pronunciation, pronunciation'') is a U.S. state, state in the Midwestern United States, Midwestern region of the United States. Ranking List of U.S. states and territories by area, 21st in land area, it border ...
. The most prominent example is
Interstate 93 Interstate 93 (I-93) is an Interstate Highway in the New England states of Massachusetts, New Hampshire, and Vermont in the United States. Spanning approximately along a north–south axis, it is one of three primary Interstate Highways ...
in Franconia Notch State Park (before dropping down to a single lane in each direction, plus a steel divider). The mode is not unknown in the United States off Interstate roads, including for example
California State Route 1 State Route 1 (SR 1) is a major north–south 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 Route number, ...
between Malibu and
Oxnard Oxnard () is a city in Ventura County in the U.S. state of California, United States. On California's Central Coast (California), Central Coast, it is the most populous city in Ventura County and the List of largest California cities by populati ...
,
Arizona State Route 77 State Route 77 (SR 77) is a long state highway in Arizona that traverses much of the state's length, stretching from its southern terminus at a junction with I-10 in Tucson to its northern terminus with BIA Route 6 at the Navajo Nation boundar ...
north of
Oracle An oracle is a person or thing considered to provide insight, wise counsel or prophetic predictions, most notably including precognition of the future, inspired by deities. If done through occultic means, it is a form of divination. Descript ...
, U.S. Route 412 between Salem and Mountain Home, and the section of
Missouri Route 5 Missouri Route 5 is the longest state highway in Missouri and the only Missouri state highway to traverse the entire state. To the north, it continues into Iowa as Iowa Highway 5 and to the south it enters Arkansas as Arkansas Highway 5 as pa ...
between the towns of
Lebanon Lebanon, officially the Republic of Lebanon, is a country in the Levant region of West Asia. Situated at the crossroads of the Mediterranean Basin and the Arabian Peninsula, it is bordered by Syria to the north and east, Israel to the south ...
and Camdenton. In the United States, this term is not used and roads that would be in a configuration that could be described as 2+1 usually have an extra added climbing lane on steep grades for trucks and slow vehicles to climb or are dropping or expanding to 2 or 4 lanes respectively. These roads also exist in
Texas Texas ( , ; or ) is the most populous U.S. state, state in the South Central United States, South Central region of the United States. It borders Louisiana to the east, Arkansas to the northeast, Oklahoma to the north, New Mexico to the we ...
, called " Super 2", as that term has more than one definition. In the 1950s,
New York New York most commonly refers to: * New York (state), a state in the northeastern United States * New York City, the most populous city in the United States, located in the state of New York New York may also refer to: Places United Kingdom * ...
state built many highways which totalled 3 lanes wide, with traffic moving in either direction permitted to use the center lane for passing. After less than ten years of a frighteningly high head-on collision rate, all were re-striped into either two wide lanes, or a one-direction passing lane, or alternating between the two systems.


Elsewhere

Divided 2+1 roads are rare outside of Europe and the United States, though they are seen in a few places, such as
Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...
and the Canadian provinces of
Ontario Ontario is the southernmost Provinces and territories of Canada, province of Canada. Located in Central Canada, Ontario is the Population of Canada by province and territory, country's most populous province. As of the 2021 Canadian census, it ...
and
Quebec Quebec is Canada's List of Canadian provinces and territories by area, largest province by area. Located in Central Canada, the province shares borders with the provinces of Ontario to the west, Newfoundland and Labrador to the northeast, ...
. In Japan, a 2+1 road was implemented in the northern island of Hokkaido.Kazunori Munehiro (2015), Performance Evaluation of 2+1 Lane Highway in Hokkaido, Japan: Case Study of Saraki-tomanai Road
5th International Symposium on Highway Geometric Design, Vancouver, Canada.


See also

*
Reversible lane A reversible lane, also known as variable lane, dynamic lane, and tidal flow, is a managed lane in which traffic may travel in either direction, depending on certain conditions. Typically, it is meant to improve traffic flow during rush hours, b ...
*
Road diet A road is a thoroughfare used primarily for movement of traffic. Roads differ from streets, whose primary use is local access. They also differ from stroads, which combine the features of streets and roads. Most modern roads are paved. The ...
*
Two-lane expressway A two-lane expressway or two-lane freeway is an limited-access road, expressway or controlled-access highway, freeway with only one lane (road), lane in each direction, and usually no Jersey barrier, median barrier. It may be built that way becau ...
* Super 2 * 2-1 road * Dual carriageway


References


External links

*Iris
National Roads Authority

Interim Advice Note on Road Link Design for 2+1 roads
(
PDF Portable document format (PDF), standardized as ISO 32000, is a file format developed by Adobe Inc., Adobe in 1992 to present documents, including text formatting and images, in a manner independent of application software, computer hardware, ...
4.7 MB)
Major Road Schemes in Ireland 2008 update

NCHRP Research Synthesis #275 on 2+1 Roadway Design Standards
{{DEFAULTSORT:2 1 Road Road surface markings Types of roads Articles containing video clips