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In the field of road transport, an interchange is a road junction that typically utilizes grade separation, and one or more ramps, to permit traffic on at least one road to pass through the junction without crossing any other traffic stream. It differs from an intersection, at which roads cross at grade. Interchanges are almost always used when at least one of the roads is a freeway, though they may occasionally be used at junctions between two surface streets. ImageMetadata File history File links Download high resolution version (2032x976, 497 KB) Freeway interchange in Los Angeles, California. ...
ImageMetadata File history File links Download high resolution version (2032x976, 497 KB) Freeway interchange in Los Angeles, California. ...
Nickname: City of Angels Location within Los Angeles County in the state of California Coordinates: State California County Los Angeles County Mayor Antonio Villaraigosa Area - City 1,290. ...
Disruptions in organized traffic flow can create delays lasting hours. ...
A junction, when used in the context of traffic is a place where several traffic routes cross, eg. ...
An example of a four-level stack interchange in the Netherlands. ...
This article or section does not cite its references or sources. ...
In the field of road transport, an intersection is a road junction where two or more roads either meet or cross at grade (they are at the same level). ...
An at-grade intersection is a junction at which two or more transport axes cross at the same level (or grade). ...
A freeway is a type of highway that is designed for safer high-speed operation of motor vehicles through the elimination of at-grade intersections. ...
Terminology  A Mercedes-Benz station wagon exiting a freeway. Note: The descriptions of road junctions are for countries where vehicles drive on the right side of the road. For countries where driving is on the left the layout of the junctions is the same, only left/right is reversed. The Trikke is a Human Powered Vehicle (HPV) This article is about the means of transport. ...
drive on right drive on left Traffic going in opposite directions should be separated in such a way that they do not block each others way. ...
Layout, in publishing, is the process of arranging editorial content, advertising, graphics and other information in a manner that creates an effective presentation. ...
- A freeway junction or highway interchange (in the US) or motorway junction (in the UK) is a type of road junction, linking one motorway to another; to other roads; or sometimes to just a motorway service station. In the UK, all junctions on a motorway with other roads are numbered - the first being called "Junction 1", etc. In the US, interchanges are either numbered according to cardinal interchange number, or by mileage.
- A highway ramp (as in exit ramp and entrance ramp) or slip road is a short section of road which allows vehicles to enter or exit a freeway (motorway).
- A directional ramp always tends toward the desired direction of travel. This means that a ramp that makes a left turn exits from the left side of the roadway (a left exit). Left directional ramps are relatively uncommon as the left lane is usually reserved for high-speed through traffic. Right ramps are almost always directional.
- A non-directional ramp goes in a direction opposite to the desired direction of travel. Many loop ramps (as in a cloverleaf) are non-directional.
- A semi-directional ramp exits a road in a direction opposite from the desired direction of travel, but then turns toward the desired direction of travel. Many 'flyover ramps' (as in a stack) are semi-directional.
- A U-Turn ramp leaves the road in one driving direction, turns over it and rejoins in the opposite direction.
Weaving is an undesirable situation in which traffic veering right and traffic veering left must cross paths within a limited distance, to merge with traffic on the through lane. In the worst circumstances, a large portion of through traffic must change lanes to stay on the same roadway. Weaving creates both safety and capacity problems. Some interchanges use collector/distributor roads to deal with weaving--while doing so does not eliminate the problem entirely, it separates the weaving traffic from the freeway's main lanes, thus improving traffic flow. Some areas that had such bad junctions have gone through the expensive process of "unweaving the weave" to improve traffic flow. United States is the current Good Article Collaboration of the week! Please help to improve this article to the highest of standards. ...
Motorway symbol in UK, France and Ireland. ...
A motorway service station is a place where drivers can leave a motorway to refuel, rest, or take refreshement. ...
A freeway is a type of highway that is designed for safer high-speed operation of motor vehicles through the elimination of at-grade intersections. ...
Motorway symbol in UK, France and Ireland. ...
Overpass in East Potomac Park, Washington, D.C. Flyover in Miami Beach, Florida An overpass (In UK, India, Hong Kong flyover) is a bridge, road or similar structure that crosses over another road. ...
A collector/distributor road, often abbreviated as C/D road, is a one-way road next to a freeway that is used for some or all of the ramps that would otherwise merge into or split from the main lanes of the freeway. ...
The German Autobahn system splits Autobahn-to-Autobahn interchanges into two types - Autobahnkreuz (AK, translates as motorway cross), a crossing of two Autobahns (or something more complicated), and Autobahndreieck (AD, translates as motorway triangle), an interchange where one of the Autobahns ends. It has been suggested that this article or section be merged into freeway. ...
Complete interchanges A complete interchange has enough ramps to provide access from any direction of any road in the junction to any direction of any other road in the junction.
Barring u-turns, a complete interchange between two freeways requires eight ramps, while a complete interchange between a freeway and another road (not a freeway) requires at least four ramps. Using u-turns these numbers can be halved to four and two respectively, by making cars that want to turn left pass by the other road first, then make a u-turn and turn right. The use of u-turn ramps is common in less wealthy countries.
The general rule today is that freeways should have at least one mile between interchanges to prevent excessive weaving between entering and leaving traffic. Unfortunately, most older freeway interchanges do not follow this rule (and are congested as a result).
Types of interchanges
- A cloverleaf is a two-level interchange in which left turns are handled by loop ramps. To go left, vehicles first pass either over or under the other road, then bear right onto a one-way ramp that loops 270 degrees to the right and then merges onto the intersecting road. (In countries where cars drive on the left, this would be a left turn.) The major advantage of cloverleafs is that they require only one bridge, which makes such junctions cheap if land is plentiful. A major problem with cloverleafs is weaving (see definition of weaving, above). Cloverleafs also have a considerable land consumption which means that while they are common in the United States, Canada, Germany, and Netherlands, only four such junctions are found in the short-of-land United Kingdom, with just one on the motorway network (partial cloverleaf exists where the M25 meets the M40 west of London). In Germany the standard design is to separate all turning traffic into a parallel lane so that the extra road space minimizes the problem of weaving. Cloverleaves are often seen in urban highways within cities that grow out instead of growing up.
- A stack is an interchange in which left turns are handled by semi-directional flyover ramps. In order to go left, vehicles first turn slightly right (on a 'right-turn' ramp), then go left on a ramp which goes over (or under) both freeways and connects to the 'right-turn' ramp in the opposite quadrant of the interchange. A stack interchange, then, has two pairs of left-turning ramps, which can be "stacked" in various configurations above or below the two through routes. Stacks do not suffer from the problem of weaving associated with cloverleafs, but require massive construction works. A basic stack involves roads on four levels, but in stacks including ramps for direct movement between high occupancy vehicle lanes, even more levels of stack can be needed; the interchange between Interstate 105 and Interstate 110 in Los Angeles County, California, is a five-level stack. This is not only expensive, but also unsightly, leading to considerable NIMBY opposition.
An alternative to the stack which requires fewer levels while retaining semi-directional ramps throughout has the left-turning ramps sweep around the center of the interchange in a spiral pattern. This has slightly less capacity because the ramps turn and change height more quickly. One example of a freeway-to-surface street ramp in this style would be the Interstate 696/Mound Road interchange in Warren, Michigan. [1] Another example is the Interstate 95/U.S.Highway 6/Memorial Blvd. interchange in Providence, Rhode Island. [2] A freeway is a type of highway that is designed for safer high-speed operation of motor vehicles through the elimination of at-grade intersections. ...
Stacked highway interchange near The Hague, Netherlands Source and ©: picture archive of the ministry of traffic (V&W), Netherlands, 1983. ...
Stacked highway interchange near The Hague, Netherlands Source and ©: picture archive of the ministry of traffic (V&W), Netherlands, 1983. ...
Arms of The Hague Flag of The city of The Hague. ...
Los Angeles, California. ...
Los Angeles, California. ...
Nickname: City of Angels Location within Los Angeles County in the state of California Coordinates: State California County Los Angeles County Mayor Antonio Villaraigosa Area - City 1,290. ...
Image File history File links Petlja_2. ...
Image File history File links Petlja_2. ...
Zagreb (pronounced: ) is the largest and capital city of Croatia. ...
Trumpet highway interchange near Arnhem, Netherlands Source and ©: picture archive of the ministry of traffic (V&W), Netherlands, 1984. ...
Trumpet highway interchange near Arnhem, Netherlands Source and ©: picture archive of the ministry of traffic (V&W), Netherlands, 1984. ...
Arnhem is a municipality and a city in the east of the Netherlands, located on the Lower Rhine, and the capital of the Gelderland province. ...
A cloverleaf interchange is a two-level interchange in which right turns (in countries that drive on the left) are handled by loop ramps. ...
Motorway symbol in UK, France and Ireland. ...
The M25 motorway looking south between junctions 14 and 15, near Heathrow Airport. ...
The M40 in Warwickshire The M40 motorway is the second motorway in the English transport network to connect London to Birmingham. ...
full of cockneys. ...
A stack interchange is a free-flowing junction between two or more roads that allows turning in all directions. ...
A permanent, separated high-occupancy vehicle lane on I-91 in Connecticut A high occupancy vehicle (or HOV) is any vehicle with a driver and one or more (or sometimes two or more, or three or more) passengers. ...
The Glenn Anderson (Century) Freeway highlighted in red Interstate 105 (abbreviated I-105) is an interstate highway that runs east-west in southern Los Angeles County, California. ...
This Interstate Highway article needs to be cleaned up to conform to both a higher standard of article quality and accepted design standards outlined in the WikiProject U.S. Interstate Highways. ...
Los Angeles County is a county in California and is the most populous county in the United States. ...
NIMBY (an initialism for Not In My Back Yard) is an acronym for the phenomenon in which residents oppose a development as inappropriate for their local area, but by implication do not oppose such development in anothers. ...
In mathematics, a spiral is a curve which turns around some central point or axis, getting progressively closer to or farther from it, depending on which way you follow the curve. ...
Interstate 696 (abbreviated I-696) is an interstate highway entirely within the U.S. state of Michigan. ...
Mound Rd. ...
Warren is a city in Macomb County in the U.S. state of Michigan. ...
Interstate 95 (abbreviated I-95) is an Interstate highway that runs 1,927 miles (3,101 kilometers) north-south along the east coast of the United States. ...
U.S. Route 6 is a main route of the U.S. Highway system, running east from U.S. Route 395 in Bishop, California to Route 6A in Provincetown, Massachusetts (on Cape Cod) for a total of 3205 miles (5158 km). ...
Nickname: Beehive of Industry, The Renaissance City Location in Rhode Island Coordinates: Country United States State Rhode Island County Providence Mayor David N. Cicilline (D) Area - City 20. ...
A variation appropriate when the freeways meet at an angle is to have cloverleafs for the sharp left turns (less than 270° turning) and adjacent semi-directional ramps for the gentle left turns, one inside and one outside the junction. This design is compact and has no serious drawbacks.
A junction with two adjacent cloverleafs is sub-optimal and will be the result of a previous junction improvement subject to land restriction.
- A trumpet is an interchange traditionally used where one freeway terminates at another freeway; it involves at least one loop ramp connecting traffic either entering or leaving the terminating freeway with the far lanes of the continuous freeway. These junctions are also useful for toll roads as they concentrate all entering and leaving traffic in a single stretch of road, where toll booths can be installed. Double Trumpet interchanges can usually be found when a toll road meets another toll road or a freeway.
- A Directional T provides for high-speed ramps in all directions at a three-way interchange. A semi-directional T does the same, but some of the splits and merges are switched to avoid ramps to and from the passing lane.
- Hybrids, variations and rare types
A toll road, tollway, turnpike, pike or tollpike is a road on which a toll authority collects a fee for use. ...
A toll road, tollway, turnpike, pike or tollpike is a road on which a toll authority collects a fee for use. ...
A freeway is a type of highway that is designed for safer high-speed operation of motor vehicles through the elimination of at-grade intersections. ...
Diagram showing lanes and road layout, with Irish road markings. ...
Between a freeway and a non-freeway road - Diamond interchange
- Cloverleaf interchange
- Parclo interchange (partial cloverleaf - sometimes called a folded diamond when only four ramps, in two quadrants, are used)
- Single Point Urban Interchange
- Roundabout interchange--this uses a single roundabout or traffic circle which spans the freeway with two over/underpasses (either above or below the freeway). These are very common in the UK, Ireland and France, but almost unknown in the rest of Europe and the United States (though Washington, DC has several). Such junctions can be improved by adding a flyover for straight-through traffic on the non-freeway, creating a stacked roundabout.
- Dumbbell interchange - this is similar to a diamond except that it uses roundabouts rather than signals or stop signs where the ramps meet the non-freeway road.
A typical diamond interchange A diamond interchange is a common type of road junction. ...
A cloverleaf interchange is a two-level interchange in which right turns (in countries that drive on the left) are handled by loop ramps. ...
The parclo interchange (short for partial cloverleaf interchange) is a successor to the cloverleaf interchange. ...
A typical Single Point Urban Interchange. ...
A roundabout, rotary, or gyratory circus is a type of road junction (or traffic calming device) at which traffic streams circularly around a central island after first yielding to the circulating traffic. ...
It has been suggested that Cycle facilities at roundabouts be merged into this article or section. ...
A traffic circle is an intersection with a circular shape and, usually, a central island. ...
World map showing Europe A satellite composite image of Europe Europe is one of the six inhabited continents of the Earth. ...
Aerial photo (looking NW) of the Washington Monument and the White House in Washington, DC. Washington, D.C., officially the District of Columbia (also known as D.C.; Washington; the Nations Capital; the District; and, historically, the Federal City) is the capital city and administrative district of the United...
See also Image File history File links Commons-logo. ...
Wikimedia Commons logo by Reid Beels The Wikimedia Commons (also called Commons or Wikicommons) is a repository of free content images, sound and other multimedia files. ...
An example of a four-level stack interchange in the Netherlands. ...
A junction, when used in the context of traffic is a place where several traffic routes cross, eg. ...
In the field of road transport, an intersection is a road junction where two or more roads either meet or cross at grade (they are at the same level). ...
A ghost ramp is a ramp which is built (or partially built) to connect a freeway or other highway to another route which is planned or proposed, and left stranded when the latter route is abandoned or cancelled. ...
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