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why are these popular and being used to replace cloverleafs? |
Lazy Devil (talk | contribs) m Supplying a missing example. Source: Minnesota D.O.T. website |
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{{Short description|Modification of a cloverleaf interchange}}
{{Globalize|article
[[File:Derry and 407.jpg|right|thumb|upright=1.3|A parclo A4 type interchange on the [[Ontario Highway 407|Highway 407 Electronic Toll Route]] of [[List of numbered roads in Halton Region|Derry Road]] in [[Mississauga]]/[[Milton, Ontario]], [[Canada]]<br />{{coord|43.571623|n|79.789925|w}}]]
[[File:Qb interchange.jpg|right|thumb|A five-ramp parclo of [[British Columbia Highway 4|Alberni Pacific Rim BC Highway 4]] and [[British Columbia Highway 19|Inland Island Highway 19]] at [[Qualicum Beach]] in [[British Columbia]], [[Vancouver Island]] {{coord|49.324786|N|124.441373|W}}]]
A '''partial cloverleaf interchange''' or '''parclo''' is a modification of a [[cloverleaf interchange]].
The design has been well received, and has since become one of the most popular [[freeway]]-to-[[arterial road|arterial]] [[Interchange (road)|interchange]] designs in North America.{{why|date=January 2025}} It has also been used occasionally in some [[Europe]]an countries, such as [[Germany]], [[Hungary]], [[Italy]], the [[Netherlands]], and the [[United Kingdom]].
[[File:Matkus business area from air.jpg|right|thumb|alt=Diagram of a partial cloverleaf highway interchange|An aerial view of a parclo
==Comparison with other interchanges==
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The following B4 interchanges were changed from full cloverleafs:
* [[U.S. Route 73 in Kansas|U.S. 73]]/[[K-7 (Kansas highway)|K-7]] at [[U.S. Route 24 in Kansas|U.S. 24]]/[[U.S. Route 40 in Kansas|U.S. 40]]/State Avenue near [[Basehor, Kansas]], was changed in 2008.
* [[Interstate 695 (Maryland)|I-695]] at [[U.S. Route 40 in Maryland|U.S. 40]] in [[Catonsville, Maryland]], was changed in 2005/2006.
* [[U.S. Route 14 in Minnesota|U.S. 14]]/[[U.S. Route 52 in Minnesota|U.S. 52]] at Civic Center Drive in [[Rochester, Minnesota]], was changed from a cloverleaf in 2004/2005.
* [[Interstate 5 in Washington|I-5]] at South 38th Street in [[Tacoma, Washington]], was changed in the mid 1990s.
Some parclo B4 interchanges such as the intersection of [[Interstate 40]] and [[U.S. Route 401]] in [[Raleigh, North Carolina]], have been fitted with signals at each ramp meeting the arterial in order to allow more lanes on the offramps. This technique along with the ability to provide two-way signal progression along the arterial allows the parclo B4 to handle an extremely high flow of traffic along the arterial.
=== Other variations ===
[[File:Halfklaverbladaansluiting.png|thumb|upright|A parclo AB2 interchange or folded diamond.<br />Sample: The US 10/MN 23 interchange in Saint Cloud, Minnesota {{coord|45.566448|n|94.138929|W}} ]]
[[File:Parclo-AB3.svg|thumb|upright|A parclo AB3 interchange (hybrid).<br />Samples: The [[Laurensberg]] interchange in [[Aachen]], Germany {{coord|50.804072|n|6.075574|e}} and US 74/NC 51 interchange near Matthews, North Carolina {{coord|35.125862|n|80.705334|W}} ]]
Parclo designs with only two quadrants are commonly referred to as folded diamonds, due to their similarity with [[diamond interchange]]s. Sometimes the ramps in a folded diamond are actually local streets; surface roads upgraded to higher standards often do this to save money on land acquisition. This type of interchange long predates the parclo; the [[Merritt Parkway]] and [[Queen Elizabeth Way]], both built in the 1930s, used mainly folded diamonds and [[cloverleaf interchange|cloverleaves]]. Another example of this is [[Ontario Highway 401|Highway 401]]'s interchange with [[Highway 2 (Ontario)|Highway 2]] east of Tilbury (Exit 63): the ramps also have intersections fairly close to the freeway to allow traffic to continue on a rural country road (Jeannette's Creek Road / McKinlay Road) which formerly met Highway 2. One of the examples in Asia includes the [[Clark Freeport and Special Economic Zone|Clark]] South exit in [[Subic–Clark–Tarlac Expressway|SCTEX]], which is a
Depending on traffic and land needs, hybrid designs, such as the ''parclo AB'' and ''parclo A3'', can be created. A notable example of a parclo AB interchange includes the [[Ontario Highway 417|Highway 417]] and the [[Woodroffe Avenue]] interchange in [[Ottawa]]. Other variants, not describable using Ontario's system, eliminate one or more outside ramps, while leaving the loop ramps in those quadrants. In the United States, folded diamonds are frequently used in interchanges with roads that have a [[railroad]] line closely paralleling the surface street; entrance/exit ramps are not permitted to have [[level crossing]]s in modern American practice.<ref>{{cite web|author=Dan ''Dan the Man''|title=The Cloverleaf Interchange|url=http://whereroadsmeet.8k.com/article/clover.htm|access-date=2008-04-24|url-status=dead|archive-url=https://web.archive.org/web/20080514013630/http://www.whereroadsmeet.8k.com/article/clover.htm|archive-date=2008-05-14}}.</ref>
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==Implementation==
[[File:Autobahn anschluss1.jpg|thumb|An [[Autobahn]] parclo interchange variation in [[Germany]].<br />{{coord|47.6413|n|10.5278|e}}<br />The [[Nesselwang]] interchange on [[Autobahn 7]]]]
In [[California]], [[Caltrans]] currently has a policy{{Citation needed|date=September 2011}} that whenever cloverleaf interchanges between freeways and surface streets are being rebuilt, they are turned into parclo interchanges by removing some of the loop ramps (or in rare cases bridges will be added between adjacent loop ramps—see [[cloverleaf interchange]] for details).{{why|date=January 2025}}
Various forms of parclo interchanges are used on the [[North Luzon Expressway]] in the [[Philippines]]. The configuration of parclo interchanges allows for the consolidation of toll barriers at points where onramps and offramps run alongside each other. A single large barrier can serve each onramp/offramp pair simultaneously, reducing construction and operation expenses at through junctions. When possible, such as at terminal junctions, [[trumpet interchange]]s are preferred since they only require one large toll barrier for all four on/off-ramps.
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