Editing Roundabout (section)

== Types of circular intersections ==
[[File:Putrajaya_roundabout_aerial_view.jpg|thumb|upright|The world's largest roundabout, the [[Persiaran Sultan Salahuddin Abdul Aziz Shah, Putrajaya|Persiaran Sultan Salahuddin Abdul Aziz Shah]], at [[Putrajaya]], Malaysia<ref>{{Cite web|url=http://guinnessworldrecords.com/world-records/100371-largest-roundabout|title=&#124; Guinness World Records}}</ref>]]
{{mos|date=October 2021}}
Large roundabouts, such as those used at motorway junctions, typically have two to six lanes and may include traffic lights to regulate flow.

Some roundabouts have a divider or subsidiary deflection island, by means of which is provided a "free flow" segregated left- (or right-) turn lane (for the UK see [[Design Manual for Roads and Bridges]] TD 51/03) between traffic moving between two adjacent roads, and traffic within the roundabout, enabling drivers to bypass the roundabout.

=== Gyratory system ===
The term "gyratory" (for example, [[Hanger Lane gyratory]]) is sometimes used in the United Kingdom for a large circular intersection with non-standard lane markings or priority arrangements, or where there are significant lengths of carriageway between the entry arms, or when buildings occupy the central island.<ref>{{cite web|url=http://www.alaskaroundabouts.com/history.html|title=History of Roundabouts|access-date=29 November 2007|archive-url=https://web.archive.org/web/20080127234652/http://www.alaskaroundabouts.com/history.html|archive-date=27 January 2008|url-status=dead}}</ref>

In the 21st century several gyratory systems in London have been removed, including Tottenham Hale<ref>Transport for London https://tfl.gov.uk/info-for/media/press-releases/2014/november/tottenham-hale-improvement-works-complete</ref> and [[Elephant and Castle]].

=== Smaller, small and mini-roundabouts ===
{{anchor|mountable apron}}
[[File:Waterloo, Ontario, mini-roundabout at Union Street East and Margaret Avenue South.jpg|thumb|A small roundabout in [[Waterloo, Ontario]], Canada]]

As the overall or external size of a roundabout (in the UK referred to as the Inscribed Circle Diameter – ICD) is reduced, the maximum practicable (and prescribed) diameter for the central island is also reduced, whilst the width of the circulatory carriageway increases (due to the greater width of the vehicle swept path at smaller turning radii). In most cases, this results in it being too easy – certainly when traffic is light relative to capacity – for drivers to traverse the roundabout at relatively high speed, with scant regard for road markings or the potential dangers to self or conflicts with other road users. To mitigate this risk, a proportion of the circulatory carriageway – an annulus around the central island – is segregated from general use by demarcation lines and differentiated from the outer annulus of the carriageway by a combination of a slightly raised surface, adverse crossfall, contrasting colours and textures and demarcating lines. The effect of this is to discourage drivers from taking a more direct path through the roundabout, their line of least resistance is more tightly curved (and therefore slower) but more bearable. The inner annulus provides for the trailing axles of longer or articulated vehicles to sweep across the inner annulus, which is therefore known as an over-run area (in UK usage), truck apron, or mountable apron.

The smaller the roundabout, the more such mitigation measures are likely to be abused – the less effective they will be. In the UK the minimum size for roundabouts with raised islands is 28 metre diameter ICD with a 4-metre diameter island. This threshold being driven primarily by vehicle geometry – which is globally relatively consistent – rather than driver behaviour, it is adopted in other jurisdictions too. Below this minimum size, the mini-roundabout prevails.

=== Mini-roundabouts ===
After developing the offside priority rule, [[Frank Blackmore (traffic engineer)|Frank Blackmore]], of the UK's [[Transport Research Laboratory]], turned his attention to the possibility of a roundabout that could be built at sites lacking room for a conventional roundabout.<ref name="Obit-Fank_Blackmore">{{cite news | url=https://www.theguardian.com/theguardian/2008/jun/21/6 | title=Frank Blackmore Determined, maverick traffic engineer who invented the mini-roundabout | work=[[The Guardian]] | date=21 June 2008 | access-date=7 October 2013 | last=Rhodes | first=Belinda}}</ref>
{{Gallery
| align        =right
| height       =113
| width        =200
| File:Small roundabout. Kargilik.jpg
 | <small>Small roundabout in [[Kargilik Town|Kargilik]], Xinjiang, China</small>
 | alt2=
| File:Germany, Sachsen-Anhalt, Südharz, Uftrungen (1).JPG
 | <small>Mini-roundabout in [[Uftrungen]], Germany</small>
 | alt3=
| File:mini-roundabout.jpg
 | <small>A mini-roundabout in the UK, where a painted white circle is used as centre. The arrows show the direction of traffic.</small>
 | alt1=
}}
[[File:Qatar, Simaisma (9), roundabout with shops.JPG|thumb|right|Roundabout in rural [[Qatar]]]]
Mini-roundabouts can incorporate a painted circle or a low dome but must be fully traversable by vehicles. Motorists can drive over them when there is no other traffic, but it is dangerous to do so otherwise. Once the practice is established it may be difficult to discourage. Mini-roundabouts use the same right-of-way rules as standard roundabouts but produce different driver behaviour. Mini-roundabouts are sometimes grouped in pairs (a double mini-roundabout) or in "chains", simplifying navigation of otherwise awkward junctions. In some countries [[road sign]]s distinguish mini-roundabouts from larger ones.

Mini-roundabouts are common in the UK, Ireland and [[Hong Kong]] (particularly on Hong Kong Island), as well as [[Irapuato, Guanajuato|Irapuato]] in Mexico.

In the UK and also in other jurisdictions that have adopted mini-roundabouts, to drive across the central disc or dome when it is practicable to avoid it is an offence. Vehicles are required to treat the painted circle as if it were a solid island and drive around it.<ref>{{cite web|url=http://www.direct.gov.uk/en/TravelAndTransport/Highwaycode/DG_070338|title=The Highway Code – Roundabouts|access-date=14 May 2009}} Section 188, referring to Road Traffic Act 1988, Section 36, and [http://www.opsi.gov.uk/si/si2002/20023113.htm Traffic Signs Regulations & General Directions 2002], Regulations 10(1) & 16(1)</ref> Some local authorities paint double white lines around the circle to indicate this, but these require permission from the [[Secretary of State for Transport]]. The central dome also must be able to be overrun by larger vehicles.

In the UK – and also in other highway jurisdictions – the maximum size (inscribed circle diameter) for a mini roundabout is 28 metres (30 yards).{{Citation needed|date=January 2025}}

===Raindrop roundabouts===
<!-- This section is linked from [[Raindrop interchange]]. -->
These roundabouts do not form a complete circle and have a "[[wiktionary:raindrop|raindrop]]" or "[[wiktionary:teardrop|teardrop]]" shape. They have also been used at [[bowtie (road)|bowtie]] intersections, replacing traffic signals that are inefficient without a turning lane. In addition to their use at intersections, raindrop roundabouts are also used in [[dogbone interchange]]s (described [[#Motorways|below]]).
{{Clear}}

===Balcony roundabout===
A balcony roundabout is just an elevated roundabout. They are constructed in such a way that vulnerable road users can cross underneath the roundabout. Footpaths and cycle paths along the different roads connect to the square under the roundabout. Vulnerable road users do not interfere with motorised traffic on the roundabout, reducing the risk of collision.

=== Turbo roundabouts ===
[[File:Turborotonde.svg|thumb|A turbo roundabout design commonly found in the Netherlands]]

In the [[Netherlands]], [[Belgium]], [[Bosnia and Herzegovina]], [[the United Kingdom]], [[Finland]], [[Spain]], [[Poland]], [[Hungary]], [[Slovenia]], [[Slovakia]], the [[Czech Republic]], [[North Macedonia]], [[Croatia]], [[Germany]], and the U.S. states of [[Alabama]],<ref>{{cite news |last1=Chatman |first1=Bria |title=Jefferson County welcomes nation's 3rd 'turbo' roundabout |url=https://www.wbrc.com/2025/02/05/jefferson-county-welcomes-nations-3rd-turbo-roundabout |access-date=5 February 2025 |publisher=WBRC |date=5 February 2025}}</ref> [[California]], and [[Florida]], a relatively new type of two-lane roundabout designs is emerging, called "turbo roundabouts". These designs require motorists to choose their direction before entering the roundabout, thereby eliminating many conflicting paths and choices on the roundabout itself so that traffic safety is increased, as well as speed and capacity. These designs, seen from above, typically result in a spiralling flow of traffic. One minor drawback is that turbo roundabouts are often marked out such that a U-turn by means of the roundabout is not possible for drivers approaching on certain arms.

Several variations of turbo roundabouts exist. They are frequently designed for the intersection of a major road crossing a road with less traffic.

An early application of the principle was a six-arm and therefore relatively large (and fast) non-circular roundabout at [[Stairfoot]], Barnsley, South Yorkshire, which was given spiral marking about 1984. At that time the method was considered experimental and needed special consent from central authorities. The turbo roundabout was formally developed in 1996 in the Netherlands by Lambertus Fortuijn, a researcher from the [[Delft University of Technology]].<ref>{{ cite web | url = http://repository.tudelft.nl/view/ir/uuid:e01364ce-78de-465b-a8c8-39e28a4585dd/ | publisher = [[Delft University of Technology]] | title = Turborotonde en turboplein: ontwerp, capaciteit en veiligheid | trans-title = Turbo Roundabout and Turbo Circle; Design, Capacity and Safety | date = 8 January 2013 | access-date = 16 October 2014 | language = nl}}</ref> Similar roundabouts, with spiralling lane markings, have been used for many years in the UK e.g. the A176/A127 (eastbound) at [[Basildon]], Essex ({{coord|51.561399|n|0.452934|e}}). However, it was not until 1997 that the UK's national highway authorities published guidance (DMRB TA-78/97) that in effect endorsed the use of spiral markings in certain circumstances.

Turbo roundabouts can be built with raised lane separators (common in the Netherlands<ref>{{Cite web |url=https://www.crow.nl/publicaties/turborotondes |title=Turborotondes - CROW |access-date=9 July 2017 |archive-url=https://web.archive.org/web/20170926142941/http://www.crow.nl/publicaties/turborotondes |archive-date=26 September 2017 |url-status=dead }}</ref>) or with lane markings only. The use of raised lane separators prevents road users from weaving (thereby reducing conflicts) but can make manoeuvring more difficult for large vehicles.

[[File:Two-lane_roundabout_and_turborondabout_intersection_diagram.svg|thumb|A comparison between a two-lane roundabout and a turbo roundabout showing possible collision points.]]

According to simulations, a two-lane roundabout with three exits should offer 12–20% greater traffic flow than a conventional, three-lane roundabout of the same size. The reason is reduced weaving that makes entering and exiting more predictable. Because there are only ten points of conflict (compared with 8 for a conventional single lane roundabout, or between 32 and 64 with traffic signal control), this design is often safer as well. Research and experiments show that traffic accidents are reduced by 72% on turbo roundabouts compared to multi-lane roundabouts, which have 12 points of conflict.<ref>{{ cite web | url = http://www.turboroundabout.com/benefits.html | publisher = Transoft Solutions Inc. | title = Benefits of Turboroundabouts | date = 2014 | access-date = 16 October 2014 }}</ref> Research at [[Windesheim University of Applied Sciences|Windesheim University]] also shows that turbo roundabouts reduce accidents including casualties by some 75% when compared to regular intersections, and by 61% compared to single-lane roundabouts.<ref name="Windesheim">{{cite web |url=http://www.dirkdebaan.nl/blog/effecten-realisatie-turborotonde-onderzocht |title=Effecten realisatie turborotonde onderzocht |language=nl |trans-title=Effects research of turbo roundabouts |last=Vos |first=Christiaan |date=31 January 2016 |website=Verkeer – Verkeersveiligheid – Vorm (Traffic, Safety, Form) |publisher=Dirk de Baan |access-date=28 January 2017 |archive-url=https://web.archive.org/web/20170128152605/http://www.dirkdebaan.nl/blog/effecten-realisatie-turborotonde-onderzocht |archive-date=28 January 2017 |url-status=dead }}</ref> The same research made it very clear that it is safer for cyclists not to have priority over motor vehicles on the roundabout, than to have it.<ref name=Windesheim/> At least 70 have been built in the Netherlands, while many turbos (or similar, lane splitting designs) can be found in southeast Asia.<ref>{{cite web
|url=http://www.kuleuven.be/traffic/stats/download.php?id=21 |title=Capacity of a turbo-roundabout determined by micro-simulation |author1=Isaak Yperman |author2=Ben Immers |year=2003 |work=Katholieke Universiteit Leuven, Department of Civil Engineering – Transportation Planning and Highway Engineering
| format=pdf |archive-url=https://web.archive.org/web/20161227193135/http://www.kuleuven.be/traffic/stats/download.php?id=21 |archive-date=27 December 2016}} [http://www.kuleuven.ac.be/traffic/dwn/P2003D.pdf Alt URL]</ref> The turbo roundabout design is given as an example<ref>{{cite web |url=https://mutcd.fhwa.dot.gov/pdfs/2003r1r2/ch3.pdf |title=Manual on Uniform Traffic Control Devices for Streets and Highways – Part 3: Markings |year=2003 |work=U.S. Department of Transportation – Federal Highway Administration }}</ref> in the federal [[Manual on Uniform Traffic Control Devices]].

===Sub-sea roundabouts===
A new development is the roundabout below the seabed, in locations where multiple undersea traffic tunnels join. The first such roundabout is in the Eysturoy Tunnel ([[Eysturoyartunnilin]]), opened in December 2020 in the [[Faroe Islands]]. It connects the main island [[Streymoy]] with two locations on the island [[Eysturoy]] that are separated by a long fjord, [[Skálafjørður]]. So, three roads meet at this roundabout. Total length of the system is 11.24 km (6.98 mi). It was the largest ever infrastructure project in the Faroe Islands, estimated to have cost around a billion Danish kroner.<ref>For sources and references see the [[Eysturoyartunnilin|separate article]] on this tunnel and its roundabout.</ref>

=== Motorways ===
{{See also|Roundabout interchange}}
[[File:Opatovice nad Labem kruhový objezd from air K2 -1.jpg|thumb|Motorway junction with roundabout near [[Opatovice nad Labem]], Czech Republic]]

Roundabouts are generally not appropriate for placement on motorway or freeway mainlines because the purpose of such facilities is to provide for uninterrupted traffic flow. However, roundabouts are often used for the junction between the slip roads (called ''ramps'' in North America) and the intersecting road. A single roundabout, [[grade separation|grade separated]] from the mainlines, may be used to create a [[roundabout interchange]]. This type of junction is common in the UK and Ireland.

Alternatively, separate roundabouts also may be used at the slip road intersections of a [[diamond interchange]] to create what often is referred to as a "[[dumbbell interchange]]", which is increasingly common in both Europe and [[North America]] due to its reduced need for wide or multiple bridges. A variation of the dumbbell interchange, often called a "[[dogbone interchange]]", occurs when the roundabouts do not form a complete circle but are instead raindrop roundabouts (described [[#Raindrop roundabouts|above]]). This configuration reduces conflicts between vehicles entering the raindrop roundabouts from the ramps, reducing queueing and delays, compared with the dumbbell interchange.

Additional use of roundabouts for high-speed junctions is the [[roundabout interchange#Three-level stacked roundabout|3-level stacked roundabout]]—this is a [[roundabout interchange]] where ''both'' of the roadway mainlines are grade separated. In the United Kingdom, the [[M25 motorway|M25]]/[[A3 road|A3]], [[M8 motorway (Great Britain)|M8]]/[[M73 motorway|M73]] and [[A1 road (Great Britain)|A1(M)]]/[[M18 motorway (Great Britain)|M18]] interchanges are examples of this type. These junctions, however, have less capacity than a full [[free-flow interchange]]. A similar design to this is the [[three-level diamond interchange]].

Most junctions on [[Dublin]]'s M50 motorway C-road were built using a standard roundabout interchange. The traffic volume of several of these junctions increased to a level higher than the capacity such roundabouts can accommodate, and in turn, have been converted into partially or fully free-flowing interchanges. One example is the [[Red Cow interchange]]. In [[Northern Ireland]], the junction between the [[M1 motorway (Northern Ireland)|M1]] and [[M12 motorway|M12]] (Craigavon connector motorway) is via a standard roundabout with a raised centre, three onslips and three offslips, and two lanes.

In the city of [[Malmö]], Sweden, a roundabout connects two motorways, E22 from [[Lund]], and the [[Inre Ringvägen|Inner ring road]].

In the Netherlands, [[A6 motorway (Netherlands)|A6 motorway]] and [[A7 motorway (Netherlands)|A7 motorway]] used to cross near [[Joure]] using a roundabout until October 2017, when the junction was turned into a full [[Interchange (road)#Directional T interchange (Y-interchange)|Y-interchange]].<ref>{{Cite web|url=https://www.lc.nl/friesland/Video-Eerste-rit-over-het-nieuwe-knooppunt-Joure-22575041.html|title=Video: Eerste rit over het nieuwe knooppunt Joure|website=Leeuwarder Courant|date=13 October 2017 }}</ref> The junction between the [[A200 motorway (Netherlands)|A200]] and the [[A9 motorway (Netherlands)|A9]] uses a 3-level stacked roundabout. Near [[Eindhoven]] (the Leenderheide junction), the junction for the [[A2 motorway (Netherlands)|A2]] uses a roundabout. An overpass was built for the [[A67 motorway (Netherlands)|A67]] from Antwerp to Germany.

Near [[Liège]], Belgium, the Cheratte interchange between the [[A3 motorway (Belgium)|A3/E40]] and [[A25 road (Belgium)|A25/E25]] functions partially as a roundabout, with through traffic allowed to continue without entering the junction and traffic changing between motorways required to use the roundabout.

Rotary interchanges operate with [[traffic circle]]s rather than roundabouts. Rotary interchanges are common in [[New England]], particularly in the state of [[Massachusetts]], but a European example of a rotary interchange may be found in [[Hinwil]], Switzerland.

=== Signalised roundabouts ===
[[File:Old Market Roundabout, Bristol.jpg|thumb|A major signal-controlled roundabout interchange in central [[Bristol]], England. Vehicles drive on the left, and vehicles in the roundabout are stopped by traffic lights to allow other vehicles to enter, while an [[underpass]] permits straight-through traffic to bypass the roundabout entirely.]]

A signalised roundabout is one where one or more entry is controlled by traffic signals, rather than by assumed priority. For each signalised entry there will also be a signalised stopline immediately upstream on the circulatory section. The signals prevent blocking on the roundabout, and balance and improve traffic capacity.<ref>UK Department for Transport, Signal Controlled Roundabouts LTN 1/09</ref>

Examples include the M50 in Dublin; the Cherry Street roundabout in [[Kowloon]], Hong Kong; Sheriffhall Roundabout in Edinburgh, Scotland; Newton Circus in [[Singapore]]; and many of the roundabouts along the [[Paseo de la Reforma]] in [[Mexico City]].

An evolution of the signalised roundabout has been proposed recently.<ref>{{cite journal |last1=Ibanez |first1=Guillermo |title=Synchronous Roundabouts with Rotating Priority Sectors (SYROPS): High Capacity and Safety for Conventional and Autonomous Vehicles |journal=Electronics |date=2020 |volume=9 |issue=10 |page=1726 |doi=10.3390/electronics9101726 |doi-access=free |hdl=10017/44928 |hdl-access=free }}</ref> It is based in avoiding stops by eliminating conflict points in roundabouts. This proposed new paradigm (SYROPS) forms platoons of vehicles (e.g. 2 x 3 cars) that arrive at the roundabout with speed identical to the average circulation speed in the roundabout and within the time interval (visualised as a rotating priority sector) assigned to his entrance, avoiding all the conflicts of passage and with it the stops and accelerations required in standard and in signalled roundabouts. Signalling signage is with lights for human drivers and optionally wireless for connected and autonomous vehicles.{{undue weight inline|date=October 2022}}

=== "Magic" roundabouts/ring junctions ===
{{anchor|"Magic" roundabouts|Magic roundabout|ring junction}}
"Magic roundabouts" direct traffic in both directions around the central island. They are officially known as "ring junctions". The [[Magic Roundabout (Swindon)|first magic roundabout]] was constructed in 1972 in [[Swindon]], Wiltshire, United Kingdom, designed by [[Frank Blackmore]],<ref name="timesonline1">{{cite news |title=Frank Blackmore: traffic engineer and inventor of the mini-roundabout |url=http://www.timesonline.co.uk/tol/comment/obituaries/article4131930.ece |archive-url=https://web.archive.org/web/20100524152615/http://www.timesonline.co.uk/tol/comment/obituaries/article4131930.ece |url-status=dead |archive-date=24 May 2010 |work=The Times |date=14 June 2008 |access-date=15 June 2008 |location=London}}</ref> inventor of the mini-roundabout. The roundabout joins five roads and consists of a two-way road around the central island, with five mini-roundabouts meeting the incoming roads.<ref>{{Citation |title=Swindon's Magic Roundabout from the air |url=https://www.youtube.com/watch?v=Kafx_GGHqVg |language=en |access-date=23 March 2022}}</ref>

The name derives from the popular children's television series, ''[[The Magic Roundabout]]'', and is considered "magic" because traffic flows in both clockwise and anticlockwise directions. This is achieved by surrounding the main island with one smaller roundabout per entry/exit street. This pattern directs traffic in the usual clockwise (in [[Left- and right-hand traffic|LHT]] installations) or counter-clockwise (in [[Left- and right-hand traffic|RHT]] installations) manner around each mini-roundabout. Exiting the mini-roundabouts, traffic may proceed around the central island either in the usual direction (via the outer loop), or in the inverse direction (the inner loop). The arrangement offers multiple paths between feeder roads. Drivers typically choose the shorter, most fluid route. Although the safety record is good,{{cn|date=September 2024}} many drivers find this system intimidating, and some drivers go to great lengths to avoid them.<ref>[http://www.easier.com/view/News/Motoring/article-33515.html Brits vote on the best and worst roundabouts], Easier.com. 20 December 2005, retrieved 18 January 2008</ref><ref>{{Cite web|url=https://www.autoexpress.co.uk/car-news/29798/world-s-worst-junctions|title=World's worst junctions revealed|website=Auto Express}}</ref><ref>[http://news.bbc.co.uk/1/hi/england/london/7140892.stm 10 Scariest Junctions in the UK], BBC, 27 November 2009.</ref>

Similar systems are found in the [[Magic Roundabout (Hemel Hempstead)|Moor End roundabout]] in [[Hemel Hempstead]] (Hertfordshire), which has six intersections; in [[Magic Roundabout (High Wycombe)|High Wycombe]] (Buckinghamshire),<ref>{{google maps|url=https://www.google.co.uk/maps/@51.6268496,-0.7505916,18.67z|title=High Wycombe}}</ref> the [[Denham Roundabout]] in [[Denham, Buckinghamshire|Denham]] (Buckinghamshire), the [[Magic Roundabout (Colchester)|Greenstead Roundabout]] in [[Colchester]] (Essex), "[[The Egg (roundabout)|The Egg]]" in [[Tamworth, Staffordshire#The Egg Roundabout|Tamworth]] (Staffordshire) and the [[Hatton Cross]] Roundabout in London.<ref>{{google maps|url=http://maps.google.co.uk/maps?ll=51.467877,-0.423285&spn=0.003068,0.00392 |title=Hatton Cross}}</ref>

[[Churchbridge Junction]] in [[Staffordshire]] is a magic gyratory. This type of junction is similar to a magic roundabout, except that the constituent roundabouts are connected by longer lengths of roadway.<ref name="sabre_magic">{{cite web|title=SABRE: Magic Gyratory|url=http://www.sabre-roads.org.uk/wiki/index.php?title=Magic_Gyratory|access-date=8 November 2013|date=8 November 2013}}</ref>

<gallery widths="200px" heights="150px" class="center">
Magic Roundabout Schild db.jpg|The [[Magic Roundabout (Swindon)|Swindon Magic Roundabout]]
Swindon_magic_roundabout.svg|Map with traffic direction and two routes from Fleming Way to Queen's Drive
</gallery>

=== Dutch-style roundabouts for bicycles and pedestrians ===
{{see also|Protected intersection#Protected roundabouts}}
[[File:Alternative_dutch_roundabout.png|thumb|Dutch-style roundabout]] [[File:Trams at Nationaltheatret.jpg|thumb|Near [[Nationaltheatret]] in [[Oslo]], [[tram]]ways cross the roundabout]]
[[File:Haymarket roundabout 018.JPG|thumb|[[Haymarket roundabout]], [[Melbourne]]]]

=== Trams ===
[[Tram]] roundabouts, which are found in many countries, combine roundabouts for individual vehicles with tram lines. Large areas are needed for tram roundabouts that include a junction between tram lines. Tramways usually cross the centre of the roundabout. At busy junctions, this requires traffic lights or special signalling granting the trams priority. However, there are also roundabouts where trams and vehicles share the carriageway. Some roundabouts have a tram stop on the island.

*In France, tram roundabouts commonly have radii between 14 and 22 metres, although some have radii outside this range.<ref name="utp.fr">{{Cite web |url=https://www.utp.fr/sites/default/files/Dpt_AET/201706_Cerema-STRMTG_Giratoires_et_tramways.pdf |title=Archived copy |access-date=19 October 2019 |archive-url=https://web.archive.org/web/20191019114458/https://www.utp.fr/sites/default/files/Dpt_AET/201706_Cerema-STRMTG_Giratoires_et_tramways.pdf |archive-date=19 October 2019 |url-status=dead }}</ref>
*In some cities, the tramway bisects the roundabout. The French {{ill|Cerema|fr}} considers that the mix of priorities makes these confusing and difficult to understand: a traditional modern roundabout gives the priority to the central ring, while tram roundabouts give priority to the central ring but higher priority still to the tramway. This generates many collisions of cars and trams, between 7 and 10 for each tram roundabout in France between 2006 and 2015 (between 0.37 and 1.01 per year).<ref name="utp.fr" />{{contradictory-inline|reason=the per-year figures don't multiply up to the figures over 11 years|date=September 2020}}
*In inner [[Melbourne]], particularly in the inner suburban area of [[South Melbourne]], where the [[Trams in Melbourne|tram network]] is extensive, tram tracks always pass through the central island, with drivers required to give way to vehicles approaching from their right and to trams approaching from right angles. The [[Haymarket roundabout]] between [[Royal Parade, Melbourne|Royal Parade]] and [[Elizabeth Street, Melbourne|Elizabeth Street]] contains a tram-stop, pedestrian crossings, three entering tram lines, traffic signals to stop vehicular traffic at each crossing point when a tram is due, service roads and a pedestrian crossing.
*[[Brussels]] tram roundabouts employ multiple configurations. At the Barrière de [[Saint-Gilles, Belgium|St-Gilles]] (Dutch: {{lang|nl|Bareel St-Gillis}}), tram tracks form a circle in the carriageway, while Churchill, Verboekhoven and Altitude Cent (''Hoogte Honderd'') have reserved tram tracks inside the roundabout. At Vanderkindere and Place Stéphanie (''Stefaniaplein''), they go straight through the centre, in the latter case with a slip track up the Chaussée de Charleroi (''Charleroisesteenweg''), while at Montgomery they tunnel underneath.
*In Dublin, Ireland, the [[Red Cow interchange]] at the [[N7 road (Ireland)|N7]]/M50 junction is grade-separated and is signal-controlled with secondary lanes (separate from the main roundabout) for those making left turns. The junction, the busiest in Ireland, had tram lines added to it with the opening of the [[Luas]] system in 2004. The tracks pass across one carriageway of the N7, and across the southern M50 sliproads. Trams pass every five minutes at rush hour. The roundabout was replaced with a grade-separated free flowing junction.
*[[Gothenburg, Sweden]] has a tram roundabout at Mariaplan in the inner suburb of Majorna. The trams make a right turn, giving the roundabout an odd design.
*In [[Warsaw]], trams typically cross straight through roundabouts and have junctions in the centre of them. In [[Wrocław]], Poland, trams pass through the Powstańców Śląskich Roundabout, stopping in the roundabout (north-headed track).
*The [[Silesian Interurbans|Silesian tram network]] in Poland has two tram roundabouts. In the city centre of [[Katowice]], the tram line passes through the centre of the Ziętka Roundabout in a north–south alignment, with a tram stop in the centre of the circle.{{efn|There is also a branch line immediately north of the roundabout going west, and an additional tram stop on that branch.}} In [[Będzin]], unusually, the tram junction itself forms a circular roundabout, with trams going around the circle; there are tram stops immediately outside the roundabout on each branch.
*In Vítězné náměstí (Victory Square) in [[Prague]], Czech Republic, a tramway crosses the carriage way of the roundabout at three places. Entering as well as leaving trams give way to vehicles. In the years 1932–42 trams circulated much like vehicles.<ref>[http://www.prazsketramvaje.cz/view.php?cisloclanku=2006041435 Vítězné náměstí], Prague trams fun web</ref>
*In [[Kyiv]], Ukraine an interchange of two "[[Trams in Kyiv|fast tram]]" lines is below a roundabout.
*[[Oslo]], Norway also has many roundabouts with [[Oslo Tramway|tram]] tracks passing through; for example at Bislett, Frogner plass, [[Sinsen]], Solli plass, Carl Berners plass and Storo.
*In [[Wolverhampton, England]], the [[West Midlands Metro]] tram passes through the centre of a roundabout on the approach to its terminus at [[Wolverhampton St George's tram stop|St Georges]]. This also happens in [[New Addington]] in [[Croydon]] on the [[Tramlink]] north of [[King Henry's Drive tram stop]] on Old Lodge Lane at the junction to King Henry's Drive.
*In [[Sheffield, England]] the [[Sheffield Supertram]] systems crosses two major roundabouts. At the Brook Hill roundabout near [[University of Sheffield|Sheffield University]], the tramway passes underneath the roundabout in a subway, while at Park Square in the city centre it travels above the roundabout on bridges and viaducts with a junction in the central island.
*A roundabout in southern [[Zagreb]], Croatia features tram tracks passing through, curving at a 90° angle, as well as a full tram mini-roundabout inside the middle road island. In Croatia, where tram tracks enter the road without traffic lights, trams have the highest priority and other non-emergency vehicles are required to yield.
*In [[Salt Lake City, Utah]] a [[light rail]] line on the south side of the [[University of Utah]] crosses a roundabout where Guardsman Way meets South Campus Drive. Like virtually all rail crossings in the United States, both crossings in the circle are equipped with [[boom barrier]]s.
*In [[Kassel]], Germany, Lines 4 and 8 pass through the centre of the roundabout at Platz der Deutschen Einheit. The tram stops are in the centre of the roundabout. Roundabout traffic is controlled by traffic lights. Pedestrian access is via subway and street-level crossings at the lights.
*In [[Bremen]], Germany, tram lines 8 and 6 pass through the centre of the roundabout "Am Stern" east of the main railway station. They enter from the west and exit in a northeastern direction, thus making a slight bend within the roundabout. Both stations are situated on the north-eastern edge of the roundabout. Traffic is controlled by two-colour traffic lights inside the roundabout.

=== Railways ===
[[File:Blenheim Main Street Roundabout looking north (LCM20210404).jpg|thumb|The [[Main North Line, New Zealand|Main North Line]] railway bisects the {{NZlSH|1}}/Main Street roundabout in [[Blenheim, New Zealand|Blenheim]], New Zealand.]]
In [[Jensen Beach, Florida]], the main line of the [[Florida East Coast Railway]] running north–south bisects the two-lane roundabout at the junction of Jensen Beach Boulevard running east–west. It hosts three other roads and the service entrance to a large shopping plaza. Boom barriers line the railway crossings. The landscaped central island bisected by the tracks was originally [[kerb]]ed, but [[semi-trailer truck|18-wheelers]] had trouble negotiating the roundabout, so the kerbs were replaced with painted concrete strips. The roundabout was built in the early 2000s and improved traffic flow, although long freight trains often cause delays.<ref>{{google maps |url= http://maps.google.co.uk/maps?hl=en&q=27.24395,+-80.22742&safe=active&um=1&ie=UTF-8&hq=&hnear=0x88dee7066d9fab49:0xd4730553b50a5cbf,%2B27%C2%B0+14'+38.63%22,+-80%C2%B0+13'+38.60%22&gl=uk&ei=aIUNTszzGMqphAe-5NXfDQ&sa=X&oi=geocode_result&ct=image&resnum=1&ved=0CBkQ8gEwAA |title Jensen Beach Boulevard Roundabout |access-date= 15 January 2012}}</ref><ref>{{cite web|url=http://www.tcrpc.org/departments/studio/jensen_beach_downtown_charrette/roundabouts/roundabouts_home.htm|title=Jensen Beach Roundabouts Charrette|access-date=16 October 2007|archive-date=21 November 2008|archive-url=https://web.archive.org/web/20081121070652/http://www.tcrpc.org/departments/studio/jensen_beach_downtown_charrette/roundabouts/roundabouts_home.htm|url-status=dead}}</ref>

Two roundabouts in the Melbourne metropolitan area, [[Highett, Victoria]]<ref>{{cite web|url=http://www.street-directory.com.au/aust_new/index.cgi?CountryName=vic&x=145.039044269836&y=-37.9447586507931&level=6|work=Australia Mapsearch|title=145.039044269836,-37.9447586507931}}</ref> and [[Hampton, Victoria|Hampton]],<ref>{{cite web|url=http://www.street-directory.com.au/aust_new/index.cgi?CountryName=vic&x=144.9930580000&y=-37.9200150000&level=6|work=Australia Mapsearch|title=144.9930580000&,-37.9200150000}}</ref> have [[passenger rail terminology#Heavy rail|heavy rail]] crossing the roundabout and through the inner circle. Boom barriers protect the railway from oncoming traffic at the appropriate points in the roundabout.

At the Driescher Kreisel<ref>{{Cite web|url=http://www.bergischgladbach.de/driescher-kreisel-1.aspx|archiveurl=https://web.archive.org/web/20110927063931/http://www.bergischgladbach.de/driescher-kreisel-1.aspx|url-status=dead|title=Der Driescher Kreisel|archivedate=27 September 2011}}</ref> in [[Bergisch Gladbach]], Germany, a railway serving a nearby paper factory crosses a roundabout located next to a shopping centre and pedestrian zone. The flow of traffic and pedestrians is governed by 14 barriers, 22 traffic lights and 8 loudspeakers. The barriers close three times daily for 7 minutes to allow trains to pass.

In New Zealand's [[South Island]], two roundabouts join major roads where a railway cuts through. One is at the intersection between {{NZlSH|1}} (as Sinclair Street and Main Street from the east) and Main Street (from the west), Park Terrace and Redwood Street in the city of [[Blenheim, New Zealand|Blenheim]]. Here the [[Main North Line, New Zealand|Main North Line]] bisects the roundabout and separates Park Terrace and Main Street eastbound from the rest of the roundabout.<ref>{{google maps |title= Blenheim Roundabout |url=https://maps.google.com.au/maps?q=-41.51345+173.95987&hl=en&sll=-41.513261,173.960298&sspn=0.004362,0.010568&vpsrc=0&t=h&z=16 |access-date= 15 January 2012}}</ref> The other roundabout is located at [[Kumara Junction]] on the [[West Coast, New Zealand|West Coast]], where the [[Hokitika Branch]] separates {{NZlSH|6}} southbound from SH 6 northbound and {{NZlSH|73}}.<ref>{{google maps |title= Kumara Junction Roundabout |url= https://maps.google.com.au/maps?q=-42.58515%09171.12974&hl=en&ll=-42.585247,171.129779&spn=0.002145,0.005284&sll=-42.585184,171.129549&sspn=0.004289,0.010568&vpsrc=6&t=h&z=18 |access-date=15 January 2012}}</ref> Both roundabouts are controlled by flashing red lights, with additional boom barriers at the Blenheim roundabout.

=== Through roundabout ===
{{anchor|Hamburger roundabout}}
Also known as a hamburger roundabout, these junctions are [[traffic light|signalised]] and have a straight-through section of carriageway for one of the major routes. The ''hamburger'' name derives from the fact that the [[plan view]] resembles the cross-section through a [[hamburger]]. The United Kingdom has examples on the [[A580 road|A580 East Lancashire Road]] in [[St Helens, Merseyside|St Helens]], on [[Haydock|Haydock Island]] in Merseyside<ref>{{google maps|url=http://local.google.co.uk/?ie=UTF8&ll=53.470883,-2.63556&spn=0.005965,0.020127&om=1|title=Haydock Island in Merseyside}}</ref> (which also features the M6 passing overhead), and on the Astley/Boothstown border.<ref>{{google maps|url=http://local.google.co.uk/?ie=UTF8&om=1&ll=53.505086,-2.431648&spn=0.00596,0.020127 Astley/Boothstown border}}</ref> More examples are the [[A6003 road|A6003]] at [[Kettering]], the [[A538 road|A538]] near [[Manchester Airport]], the "Showcase" junction on A329 at Winnersh, Berkshire<ref>{{google maps|url=https://www.google.co.uk/maps/@51.4362134,-0.8977845,267m/data=!3m1!1e3?hl=en |title=Winnersh, Berkshire}}</ref> and the A63/A1079 Mytongate junction in Hull. Examples also exist in [[Bracknell]], Hull,<ref>{{google maps|url=http://maps.google.co.uk/maps?q=hull&ie=UTF8&oe=utf-8&client=firefox-a&ll=53.740472,-0.343572&spn=0.001618,0.004828&t=h&z=18 |title=Mytongate on the A63 in Hull}}</ref> Bramcote in Nottinghamshire and [[Reading, Berkshire|Reading]], as well as on the [[N2 road (Ireland)|N2]]/[[M50 motorway (Ireland)|M50]] intersection in [[Dublin]], Ireland. In [[Perth]], Western Australia, one is found at the intersection of [[Alexander Drive]], [[Morley Drive]] and The Strand.<ref>{{google maps|url=https://maps.google.com.au/maps?q=Morley+Drive+and+Alexander+Drive&hl=en&ll=-31.889692,115.87218&spn=0.006532,0.013078&sll=-31.884409,115.872562&sspn=0.10451,0.209255&t=h&hnear=Alexander+Dr+Before+Morley+Dr&z= |title=Morley and Alexander Drive}}</ref> Throughabouts are very common in Spain, where they are called ''raquetas'' (Spanish for [[racket (sports equipment)|{{nowrap|"[tennis]}} racket"]]) or ''glorieta/rotonda partida'' ("split roundabout").<ref>{{cite web | url = http://autoescuelamiguel.com/blog/2010/cmo-circular-en-una-glorieta-partida-raqueta/ | website = Autoescuela Miguel Blog | title = Cómo circular en una Glorieta Partida (raqueta) | access-date = 17 October 2014 | language = es | quote = Explanation in the website of a driving school | archive-date = 17 October 2014 | archive-url = https://web.archive.org/web/20141017113216/http://autoescuelamiguel.com/blog/2010/cmo-circular-en-una-glorieta-partida-raqueta/ | url-status = dead }}</ref>

<gallery widths="200px" heights="200px" class="center">
Throughabout.svg|Throughabout
Throughabout Rotonde Verkeersbord 3.jpg|Throughabout road sign in the Netherlands {{coord|51.850517|N|5.831576|E}}
E37 AlexanderDr-MorleyDr sign.jpg|Throughabout road sign in Australia {{coord|31.8902952|S|115.8698988|E}}
</gallery>

==== Only bicycle-pedestrian roundabouts ====
The same features that make roundabouts attractive for roadway junctions led to their use at junctions of multi-use trails.

The [[University of California, Davis]]<ref>{{google maps|url=https://maps.google.com/maps?f=q&source=s_q&hl=en&geocode=&q=university+of+california+davis,+CA+roundabout&sll=33.709367,-117.770775&sspn=0.012513,0.018604&g=davis,+CA+roundabout&ie=UTF8&ll=38.54252,-121.753364&spn=0.001471,0.003345&t=k&z=19 |title=Davis, Ca.}}</ref>{{Original research inline|date=May 2020}} and [[Stanford University]], as well as the [[Cape Cod Rail Trail|Cape Cod]] and [[Old Colony Rail Trail|Old Colony]] rail trails have bicycle-pedestrian roundabouts. A roundabout along the [[Clear Creek Trail (Indiana)|Clear Creek Trail]] in [[Bloomington, Indiana]], connects the main [[trail]] to its [[Trail#Linear|spur]].

Roundabouts are used on off-road bicycle trails in [[Florida]], [[Colorado]], [[Alaska]], and [[Wisconsin]].<ref>Shaw, Jeffrey and Moler, Steve, [http://www.tfhrc.gov/pubrds/09janfeb/01.htm Bicyclist- and Pedestrian-Only Roundabouts, Public Roads magazine, January/February 2009] {{Webarchive|url=https://web.archive.org/web/20090510100804/http://www.tfhrc.gov/pubrds/09janfeb/01.htm |date=10 May 2009 }}</ref><ref>{{cite web|url=http://www.tfhrc.gov/safety/00068.htm|title=Federal Highway Administration Research and Technology-- – Federal Highway Administration|access-date=5 September 2006|archive-url=https://web.archive.org/web/20060923055232/http://www.tfhrc.gov/safety/00068.htm|archive-date=23 September 2006|url-status=dead}}</ref><ref>{{cite news|url=http://host.madison.com/ct/news/local/photos-bicycle-roundabout-sits-at-intersection-of-bike-paths/collection_0ae6d40a-3916-11e4-8e0d-0019bb2963f4.html|title=Bicycle roundabout sits at intersection of 3 bike paths|work=The Capital Times}}</ref>

An elevated roundabout is located in [[Eindhoven]], serving pedestrian and bicycle traffic only, above the main conventional roadway intersection. It is known as the [[Hovenring]].