# Balloon loop > Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Balloon_loop > Markdown URL: https://mediated.wiki/source/Balloon_loop.md > Source: https://en.wikipedia.org/wiki/Balloon_loop > Source revision: 1338087608 > License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) Rail loop for turning vehicles This article has multiple issues. Please help improve it or discuss these issues on the talk page. (Learn how and when to remove these messages) This article relies largely or entirely on a single source. Relevant discussion may be found on the talk page. Please help improve this article by introducing citations to additional sources. Find sources: "Balloon loop" – news · newspapers · books · scholar · JSTOR (April 2018) This article contains a pro and con list. Please help rewrite it into consolidated sections based on topics. (September 2024) (Learn how and when to remove this message) Balloon loop at Linnéplatsen at the [tramway](/source/Tram) in [Gothenburg](/source/Gothenburg), [Sweden](/source/Sweden). [Double sided](/source/Spanish_solution) [island platform](/source/Island_platform) on a balloon loop - [Olympic Park, Sydney](/source/Olympic_Park_railway_station%2C_Sydney), [Australia](/source/Australia) P1 & P4 departures P2 & P3 arrivals Maules Creek & Boggabri Coal Terminal East balloon loops A **balloon loop**, **turning loop**, or **reversing loop** ([North American Terminology](/source/Glossary_of_North_American_railway_terms)) allows a rail vehicle or train to reverse direction without having to [shunt](/source/Shunting_(rail)) or stop. Balloon loops can be useful for passenger trains and [unit freight trains](/source/Unit_train). Balloon loops are common on [tram and streetcar](/source/Tram) systems. Many streetcar and tram systems use single-ended vehicles that have doors on only one side and controls at only one end. These systems may also haul trailers with no controls in the rear car, and, as such, must be turned at each end of the route. ## History Balloon loops were first introduced on [tram](/source/Tram) and, later, [metro](/source/Rapid_transit) lines. They did not commonly appear on freight railways until the 1960s, when the modernising [British Rail](/source/British_Rail) system introduced *[merry-go-round](/source/Merry-go-round_train)* (MGR) coal trains that operated from mines to power stations and back again without [shunting](/source/Shunting_(rail)).[1] ### Tramways Light-rail train using the balloon loop at [Lechmere station](/source/Lechmere_station) in [Cambridge, Massachusetts](/source/Cambridge%2C_Massachusetts), US in 2020 On the former [Sydney](/source/Sydney) tram system, loops were used from 1881 until the second-generation system's closure in 1961. Initially, the Sydney system was operated by single-ended [steam trams](/source/Steam_trams_in_Sydney); then from the 1890s by double-ended electric trams. Lines were looped in the Sydney CBD and the other busiest areas of operation, such as the eastern suburbs lines, as they provided greater turn-around capacity on the crowded system. The Sydney system was the first example of a tramway system using loops and has continued to build them up to 1997 (third-generation system).[2] Later in the 19th century, looped streetcar (tram) lines also began to appear on systems in the US, and soon looped operation with single-ended streetcars became widely used on many North American streetcar systems. European systems were almost universally converted to looped operation in the early 20th century, and most also adopted single-ended trams.[3] Loops were also used on some tramways in Asia, South America and New Zealand, as well as on other Australian systems in addition to Sydney. Looped operation with single-ended trams is still the predominant method of tramway operation in the world,[4] in spite of the recent construction of some new, typically smaller, stubbed systems with double-ended trams. ## Usage Balloon loops are used extensively on [tramway](/source/Tram) systems with single-ended trams. Usually located at termini, the loop may be a single one-way track round a block. Single-ended trams have a cab at only one end and doors on one side, making them cheaper and having more space for passengers. On tram systems with double-ended trams balloon loops are not required but may still be used as they can provide greater turn-around capacity than a stub terminus. Balloon loops enable higher line capacity (faster turnaround of a larger number of trams) and allow the use of single-ended trams which have several advantages, including lower cost and more seating. However, double-ended trams also benefit from the capacity advantage of balloon loops. Occasionally, balloon loops are used for reversing trains on lines with heavy grades and tight curves to equalize wear on both sides of locomotives and rollingstock. Such a balloon loop was constructed at Beech Forest on the 2 ft 6 in (762 mm) Victorian Railways line from Colac to Crowes. ### Efficiency and convenience of operation - Trains can arrive and leave simultaneously, as long as an open platform exists. - Time is not lost while drivers change ends and reset the train for the other direction. - Eliminates the need for brake test if locomotives uncoupled to carry out run around the move.[*[clarification needed](https://en.wikipedia.org/wiki/Wikipedia:Please_clarify)*] ### Infrastructure optimisation - Fewer tracks and platforms are required. - Arrivals into some platforms do not block departures from other platforms. ### Train maintenance and durability - Reversal allows even wear and tear on the wheels. ### Spatial and structural constraints - Very space-consuming. - If the driver changed ends and discovers a hidden fault, delays are less likely. ### Track and train adaptability - The sharp curves cause noise,[5] as well as wear on wheels and rails. - Due to the presence of sharp curves in balloon loops, heavy haul trains are required to operate at reduced speeds to ensure safe and efficient movement.[6] - On systems, where, for reasons of economy, the couplings are made non-reversible (e.g. by fitting the air brake pipe along one side of the car only), the use of a balloon loop will cause a proportion of the rolling stock to face the "wrong" way and it may not be possible to assemble a complete train in a depot, even if sufficient cars are on hand. ### Solutions View of the balloon loop at the [temporary PATH World Trade Center station](/source/World_Trade_Center_station_(PATH)#Temporary_PATH_station) from above. - On many systems with a balloon loop, the couplings and brake hoses are made reversible. - At coal ports such as [Kooragang](/source/Kooragang#Kooragang_Island) in [Newcastle, New South Wales](/source/Newcastle%2C_New_South_Wales) the space inside the balloon loops is used for storing coal so that it is not wasted. - At the [Olympic Park station](/source/Olympic_Park_railway_station%2C_Sydney) in [Sydney Olympic Park](/source/Sydney_Olympic_Park), the loop is flattened where the platforms are located, so that the platform faces are straight. - After the opening of a loop at [Charing Cross (Embankment)](/source/Embankment_tube_station) in 1914 (replaced in 1926 by the present [Kennington loop](/source/Kennington_tube_station#Kennington_loop)) car ends were marked "A" or "B" (later, when axles were designated by letters, the "B" car ends became "D" to match the adjacent axle), and it was not permitted to couple cars together if the ends to be coupled bore the same letter. It was found necessary to provide a [turntable](/source/Railway_turntable) at [Golders Green](/source/Golders_Green_tube_station) depot (near the other end of the line), for use when there was an imbalance of car directions.[7] - The former [South Ferry](/source/South_Ferry_loops_(New_York_City_Subway)) station on the [New York City Subway](/source/New_York_City_Subway) solved the railcar door hazard by using [gap fillers](/source/Gap_filler) that extended out to the railcar door when the train triggered a switch on the tracks. The older station was closed in 2009, but was reopened between 2013 and 2017 as a result of damage to the newer station caused by [Hurricane Sandy](/source/Hurricane_Sandy). ## References 1. **[^](#cite_ref-1)** Vaughan, Adrian (1997). *Railwaymen, politics and money: the great age of railways in Britain*. London: John Murray. [ISBN](/source/ISBN_(identifier)) [978-0-7195-5746-0](https://en.wikipedia.org/wiki/Special:BookSources/978-0-7195-5746-0). 1. **[^](#cite_ref-2)** ["Trams | The Dictionary of Sydney"](https://dictionaryofsydney.org/entry/trams). *dictionaryofsydney.org*. Retrieved 2025-04-04. 1. **[^](#cite_ref-3)** ["Trolley Wire"](https://www.sydneytramwaymuseum.com.au/tramway/wp-content/uploads/2024/05/359_TrolleyWire_Nov19.pdf) (PDF). *Sydney Tramway Museum*. November 2019. 1. **[^](#cite_ref-4)** ["History of Light Rail — LRTA"](https://lrta.info/archive/mrthistory.html). *lrta.info*. Retrieved 2025-04-04. 1. **[^](#cite_ref-5)** Zuchnicka, Paulina; Korzeniowska, Joanna. ["Evaluation of traffic noise pollution in chosen sites in Krakow"](https://www.researchgate.net/publication/350358182). *Logistyka*: 9980–9986. 1. **[^](#cite_ref-6)** Quan SUN, Yan; Spiryagin, Maksym; Cole, Colin; Nielsen, Dwayne (2018-10-02). ["WHEEL–RAIL WEAR INVESTIGATION ON A HEAVY HAUL BALLOON LOOP TRACK THROUGH SIMULATIONS OF SLOW SPEED WAGON DYNAMICS"](https://journals.vilniustech.lt/index.php/Transport/article/view/203). *Transport*. **33** (3): 843–852. [doi](/source/Doi_(identifier)):[10.3846/16484142.2017.1355843](https://doi.org/10.3846%2F16484142.2017.1355843). [ISSN](/source/ISSN_(identifier)) [1648-4142](https://search.worldcat.org/issn/1648-4142). 1. **[^](#cite_ref-7)** Bruce, J. Graeme (1988). "7. The First of the Standard Tube Stock 1923/25". *The London Underground Tube Stock*. Shepperton: [Ian Allan](/source/Ian_Allan_Publishing). pp. 56–57. [ISBN](/source/ISBN_(identifier)) [0-7110-1707-7](https://en.wikipedia.org/wiki/Special:BookSources/0-7110-1707-7). ## External links - Media related to [Rail track loops](https://commons.wikimedia.org/wiki/Category:Rail_track_loops) at Wikimedia Commons v t e Railway track layouts Railway track Single track Passing loop Double track Quadruple track Crossover Rail sidings Balloon loop Headshunt Pocket track Refuge siding Rail yard Classification yard Junctions Flying junction Level junction Double junction Facing and trailing Grand union Grand circle / roundabout Wye Switch / turnout / points Swingnose crossing Level crossing Stations Infill station Interchange station Terminal station Goods station Railway platform Bay Island Side Split Station layouts Balloon loop Spanish solution Cross-platform interchange Hillclimbing Horseshoe curve Zig Zag / Switchback Spiral Track geometry Track gauge Ruling gradient Minimum curve radius Cant Cant deficiency v t e Rail infrastructure Tracks (history) Axe ties Ballast Baulk road Breather switch Cant Clip and scotch Date nail Green track Fastening system Fishplate Ladder track Minimum radius Profile Tie/Sleeper Transition curve Trackwork Balloon loop Classification yard Headshunt Pocket track Junction Gauntlet track Guide bar Passing loop Track gauge dual gauge Rail track tramway track Rail yard Railway electrification overhead lines third rail ground-level power supply Railway turntable Transfer table (traverser) Roll way Siding refuge siding Switch Track geometry Water crane Water trough Wye Signalling and safety Anti-trespass panels Block post Buffer stop Catch points Defect detector Derailer Guard rail Interlocking Level crossing Loading gauge Platform screen doors Railway signal Signalling control Structure gauge Signal bridge Tell-tale Train stop Wayside horn Structures Coaling tower Freight house Head house Motive power depot/Railway workshop Platform Roundhouse Shed for trains for goods Station building clock ghost list Water stop Types Industrial Military Private station list --- Adapted from the Wikipedia article [Balloon loop](https://en.wikipedia.org/wiki/Balloon_loop) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Balloon_loop?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.