Roundabout interchange

Roundabout interchange

A roundabout interchange is an interchange between a freeway and a minor road. It can be formed either by adding an overpass to a roundabout to provide grade separation (with ramps connecting the freeway to the roundabout), or by building the roundabout above the freeway, straddling it on a pair of bridges.

Roundabout interchanges are extremely common in the United Kingdom, with hundreds on the motorway network alone. However, recent cost-cutting has meant that Raindrop interchanges (UK: "Dumbell junction") 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.

* Modern roundabout with flyover in Johnson City, NY. [http://maps.google.com/maps?f=q&hl=en&geocode=&q=johnson+city,+ny&ie=UTF8&ll=42.106254,-75.967262&spn=0.005683,0.009302&t=k&z=17&iwloc=addr]
* Traffic circle with grade separation in Latham, NY: [http://maps.google.com/maps?f=q&hl=en&geocode=&q=latham,+ny&ie=UTF8&ll=42.748084,-73.760705&spn=0.005625,0.009302&t=k&z=17]
* Roundabout (Rotary) interchanges in [http://maps.google.com/maps?q=Braintree,+MA&ie=UTF8&ll=42.210235,-70.996732&spn=0.0036,0.007296&t=h&z=17&om=1 Braintree, MA, USA] , [http://maps.google.com/maps?q=Gardner,+MA&ie=UTF8&ll=42.564156,-71.979353&spn=0.003429,0.003648&t=h&z=18&om=1 Gardner, MA, USA] , and [http://maps.google.com/maps?f=q&hl=en&geocode=&q=42.5853,+-72.6214&ie=UTF8&ll=42.585263,-72.621142&spn=0.005806,0.013947&t=h&z=17 Greenfield, MA, USA.]
* Shirlington Circle, a roundabout interchange on Interstate 395 on the border between Alexandria and Arlington County, Virginia

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.

External links

* [http://www.cbrd.co.uk/reference/interchanges/roundabout.shtml CBRD: Roundabout Interchange]
* [http://www.cbrd.co.uk/reference/interchanges/3round.shtml CBRD: Three-Level Stacked Roundabout Interchange]


Wikimedia Foundation. 2010.

Игры ⚽ Поможем написать курсовую

Look at other dictionaries:

  • Roundabout — This article is about the road junction. For other uses, see Roundabout (disambiguation). Movement within a roundabout in a country where traffic drives on the right. Note the anticlockwise circulation …   Wikipedia

  • Interchange (road) — A high capacity interchange: the Judge Harry Pregerson Interchange in Los Angeles, California, United States …   Wikipedia

  • Roundabout (disambiguation) — A roundabout is a type of road junction at which traffic enters a stream around a central island after first giving way to the circulating traffic.Roundabout may also refer to:* Carousel, a fairground ride also known as a roundabout * Roundabout… …   Wikipedia

  • Free-flow interchange — A free flow interchange is an interchange in which all roads are grade separated, and where movement from one road to another does not require the driver to stop for traffic (for example, the interchange may not include traffic lights or… …   Wikipedia

  • Cloverleaf interchange — A cloverleaf with collector/distributor roads …   Wikipedia

  • Diverging diamond interchange — Top left: Traffic enters the interchange along Missouri Route 13 Top right: Traffic crosses over to the left side of the road Bottom left: Traffic crosses over Interstate 44 Bottom right:Traffic crosses back over to the right side of the road. A… …   Wikipedia

  • Partial cloverleaf interchange — A Parclo A 4 type interchange on the Highway 407 Electronic Toll Route in Ontario A partial cloverleaf interchange or parclo is a modification of a cloverleaf interchange. The parclo interchange was developed by the Ontario Ministry of… …   Wikipedia

  • Diamond interchange — A typical diamond interchange A diamond interchange is a common type of road junction, used where a freeway crosses a minor road. The freeway itself is grade separated from the minor road, one crossing the other over a bridge. Approaching the… …   Wikipedia

  • Kingston Interchange — The Kingston Intechange is a Roundabout interchange which connects the Southern Outlet with the Huon Highway and the Channel Highway at Kingston, within the greater area of Hobart, Tasmania.The Kingston Interchange has recently been upgraded to… …   Wikipedia

  • Seberang Jaya Interchange — Malaysian expressway interchange Interchange=MES EXIT|163 MES EXIT|1503 SEBERANG JAYA Code=SJY Expressway location=MES E|1 AHN AH|2 North South Expressway Northern Route MES E|15 Butterworth Kulim Expressway Location= Seberang Jaya, Penang… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”