A roundabout interchange is a type of interchange between a controlled access highway, such as a motorway or freeway, and a minor road. The slip roads to and from the motorway carriageways converge at a single roundabout, which is grade-separated from the motorway lanes with bridges.
Antalyaspor Interchange of Antalya. The underpass serve the transit traffic of city center to Konyaaltı, while the upper part Dumlupınar Bulvarı and roundabout are maintained by General Directorate of Highways as D-400 Highway.
The western entryway into Linköping, Sweden (a branch off the backbone E4 highway) passes on a bridge above this roundabout, which connects a national road and a local road into a residential area with ramps leading up to the free-flowing road (note the green signage denoting that in these directions you are entering a motorway).
A roundabout interchange is similar to a rotary interchange, which uses a rotary rather than a roundabout. Roundabouts may also be used in conjunction with other interchange types such as a standard or folded diamond interchange, but such use should not be confused with a roundabout interchange.
Roundabout interchanges are extremely common in the United Kingdom and Ireland with hundreds on the motorway network alone. However, recent cost cutting has meant that dumbbell interchanges are increasingly used instead. These are essentially diamond interchanges with roundabouts instead of signals or stop signs where the slip roads meet the minor road. They are cheaper than roundabout interchanges as only one bridge is required instead of two.
Roundabout interchanges are much less common in North America but have been built more frequently since 1995, to improve safety, and to reduce traffic delays and bridge widening costs. However, many of the older and more dangerous rotary-style overpass interchanges have been signalized to improve throughput and safety, such as the former Drum Hill Rotary (now Drum Hill Square) in Chelmsford, Massachusetts, in New England, where such interchanges are unusually common.
A divided diamond, in which the minor road is separated into four intersections, rather than two, also acts like a roundabout interchange, but it is more square in shape and, typically, has traffic light control.
Washington Circle, in Foggy Bottom, Washington, D.C., is another example of a roundabout interchange similar to the one in Dupont Circle. Here, K Street traverses beneath the intersection.
A roundabout is used as an interchange between Quebec Autoroute 20 and Quebec Autoroute 520 in Montreal, Quebec. The roundabout is known as the Dorval Circle. Ramps to side streets are added as well. The interchange is currently[when?] being replaced.
The Rottepolderplein in the Netherlands is a three-level roundabout
Three-level stacked roundabout
The three-level stacked roundabout is a variation on the roundabout interchange in which both roads are grade-separated. It is similar to the three-level diamond interchange except that the small square of that latter interchange is enlarged to a true roundabout. If the roundabout is sufficiently large, the interchange may require only two levels.
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A roundabout interchange is a type of interchange between a controlled access highway such as a motorway or freeway and a minor road The slip roads to and from the motorway carriageways converge at a single roundabout which is grade separated from the motorway lanes with bridges Antalyaspor Interchange of Antalya The underpass serve the transit traffic of city center to Konyaalti while the upper part Dumlupinar Bulvari and roundabout are maintained by General Directorate of Highways as D 400 Highway The western entryway into Linkoping Sweden a branch off the backbone E4 highway passes on a bridge above this roundabout which connects a national road and a local road into a residential area with ramps leading up to the free flowing road note the green signage denoting that in these directions you are entering a motorway Contents 1 Design 2 Examples 3 Three level stacked roundabout 4 External linksDesign EditA roundabout interchange is similar to a rotary interchange which uses a rotary rather than a roundabout Roundabouts may also be used in conjunction with other interchange types such as a standard or folded diamond interchange but such use should not be confused with a roundabout interchange Roundabout interchanges are extremely common in the United Kingdom and Ireland with hundreds on the motorway network alone However recent cost cutting has meant that dumbbell interchanges are increasingly used instead These are essentially diamond interchanges with roundabouts instead of signals or stop signs where the slip roads meet the minor road They are cheaper than roundabout interchanges as only one bridge is required instead of two Roundabout interchanges are much less common in North America but have been built more frequently since 1995 to improve safety and to reduce traffic delays and bridge widening costs However many of the older and more dangerous rotary style overpass interchanges have been signalized to improve throughput and safety such as the former Drum Hill Rotary now Drum Hill Square in Chelmsford Massachusetts in New England where such interchanges are unusually common A divided diamond in which the minor road is separated into four intersections rather than two also acts like a roundabout interchange but it is more square in shape and typically has traffic light control Examples Edit Motorways crossing in the Czech Republic The junction of the M1 M69 and A4560 at Braunstone in England is an example of a British style in this case partially signalized roundabout interchange 52 36 2 N 1 11 42 W 52 60056 N 1 19500 W 52 60056 1 19500 Braunstone Leicestershire Kinsale Road Roundabout south of Cork Ireland on the N40 South Ring Road at the N27 Airport Road is a signalized roundabout interchange 51 52 25 N 8 28 12 W 51 87361 N 8 47000 W 51 87361 8 47000 Cork Ireland New York State Route 201 and Riverside Drive Johnson City New York has the roundabout to the side of the freeway with underpasses for the on and off ramps 42 6 25 N 75 57 59 W 42 10694 N 75 96639 W 42 10694 75 96639 Johnson City New York Denham Roundabout M40 and Oxford Road Denham Buckinghamshire connects the motorway ramps to local streets using a large circular roadway containing multiple intersections several of which are roundabouts 51 33 40 N 0 29 45 W 51 56111 N 0 49583 W 51 56111 0 49583 Denham Buckinghamshire U S Route 9 and New York State Route 2 Latham New York is a roundabout interchange with U turn lanes for the freeway 42 44 53 N 73 45 39 W 42 74806 N 73 76083 W 42 74806 73 76083 Latham New York Dupont Circle Washington D C is a roundabout interchange between several local roads including Connecticut Avenue NW which passes underneath the roundabout Washington Circle in Foggy Bottom Washington D C is another example of a roundabout interchange similar to the one in Dupont Circle Here K Street traverses beneath the intersection Echangeur de Villarcher in Voglans near Chambery is a rare example of roundabout interchange in France It links two former national roads D 1201 and D 1504 where D 1201 passes above the roundabout through a bridge 45 36 58 8 N 5 53 02 6 E 45 616333 N 5 884056 E 45 616333 5 884056 Villarcher Voglans A roundabout is used as an interchange between Quebec Autoroute 20 and Quebec Autoroute 520 in Montreal Quebec The roundabout is known as the Dorval Circle Ramps to side streets are added as well The interchange is currently when being replaced The Rottepolderplein in the Netherlands is a three level roundaboutThree level stacked roundabout EditThe three level stacked roundabout is a variation on the roundabout interchange in which both roads are grade separated It is similar to the three level diamond interchange except that the small square of that latter interchange is enlarged to a true roundabout If the roundabout is sufficiently large the interchange may require only two levels Causeway Boulevard LA 3046 and Airline Highway US 61 Metairie Louisiana has the traffic circle between the two roads 29 58 29 N 90 9 23 W 29 97472 N 90 15639 W 29 97472 90 15639 Metarie Louisiana Staples Corner A406 and A5 Dollis Hill Greater London has the roundabout on the ground 51 34 16 N 0 13 55 W 51 57111 N 0 23194 W 51 57111 0 23194 Dollis Hill London Three level stacked roundabouts are quite common in Britain because they use less land than other four way junctions where both roads are grade separated However they have lower capacity for turning movements some have had direct linking slip roads added later in an attempt to solve this problem Examples of such junctions are found at Lofthouse West Yorkshire M1 M62 53 43 55 N 1 30 47 W 53 73194 N 1 51306 W 53 73194 1 51306 Lofthouse West Yorkshire and Swanley Kent M20 M25 51 23 19 N 0 11 38 E 51 38861 N 0 19389 E 51 38861 0 19389 Swanley Kent External links EditMap all coordinates using OpenStreetMap Download coordinates as KML Retrieved from https en wikipedia org w index php title Roundabout interchange amp oldid 1111596666, wikipedia, wiki, book, 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