Balloon loop

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A Balloon loop is a track arrangement that allows a train to reverse direction, and return to where it came from, without having to shunt or even to stop.

Double sided island platform

1 Use
2 Examples
3 History
4 Disadvantages
5 Advantages
6 Other Olympic stations
7 See also

[edit] Use

Balloon loops can be useful for passenger trains, and unit freight trains, such as coal trains.

Balloon loops do not include track layouts where combinations of junctions allow a train reversal, where this reversal is not regularly used.

In some transport simulators (eg: Transport Tycoon Deluxe, 1996 but still played worldwide), Balloon Loops are referred to as RoRo stations or Roll On, Roll Out. They are frequently used at busy stations.

[edit] Examples

[edit] Passenger

South Ferry balloon loop

Olympic Park, Sydney: Platforms 1 and 4 are for boarding; platforms 2 and 3 are for alighting.
City Hall, New York City: One platform for both boarding and alighting (now closed)
South Ferry, New York City: Two tracks, two platforms (one closed)
Schwabstrasse Stuttgart S-Bahn, Loop is south of the station and completely underground
Bad Herrenalb, Albtalbahn, Germany: Train passes loop before arrival

[edit] Tram Systems

Balloon loops are used extensively on metre gauge tram systems in Germany and Switzerland, usually at the terminus of lines [1].¨These loops allow use of trams with a cab at only one end and doors on one side (like a bus). Such trams are cheaper and have more space for passengers. Other tram systems have trams constructed like normal trains, with a cab at both ends and doors on both sides, so they can be used in either direction. With Metre gauge, it is easier to construct such loops in restricted spaces.

[edit] Freight

[edit] New South Wales, Australia

Newnes Junction coal loader -
Mount Thorley - coal
Camberwell - coal
Ulan - coal
Penny Road, near Moree - wheat
Fassifern - has triangle as well, so trains can go north or south.
Vales Point
Newdell Junction - has two balloon loops.
Bargo - due to change in operational requirements, the balloon loop now points the wrong way, and requires trains to be top and tailed!

[edit] History

Balloon loops first appeared in large numbers in the 1960s when the modernising British Rail introduced so-called merry-go-round coal trains that operated without shunting from mines to power stations and back again, around the clock.

[edit] Disadvantages

The only real disadvantage of a balloon loop is that it needs a lot of space to build, and even so, the curves can be very sharp. The very sharp 180 m radius curves on the Olympic Park balloon loop cause noise, wear and tear on both the wheels and rails. Any platforms should be located on straight track, since if they are located on curved track, the gap between platform and carriage door can be a hazard.

[edit] Advantages

The advantages of a balloon loop include -

smooth operation.
trains can arrive in any free platform, while another train is leaving any platform.

If Olympic Park station were not on a balloon loop and were a stub platform:

more tracks and platforms would be required.
arrivals into some platforms could block departures from other platforms.
time would be lost while drivers change ends and reset the train for the other direction.
if the driver changed ends and discovered a hidden fault, then delays to trains would be likely.

[edit] Other Olympic stations

The Olympic station at Berlin, Germany has two through platforms and about 8 turnback platforms. This is considerably more than the 2 track / 4 platform arrangement at Sydney.