science

Sosrobahu

Sosrobahu is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Sosrobahu rather than just read about it. In short: Sosrobahu is a construction technique that allows long stretches of elevated roadway to be constructed above existing major roads with minimum disruption to traffic. The technique was designed by Indonesian engineer Tjokorda Raka Sukawati and involves the construction of the horizontal supports for the highway beside the existing road, which are then lifted and turned 90 degrees before being placed on the top of the…

Key takeaways

Sosrobahu belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Sosrobahu to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Sosrobahu from memory before moving on to harder problems.

Reference excerpt

Sosrobahu is a construction technique that allows long stretches of elevated roadway to be constructed above existing major roads with minimum disruption to traffic. The technique was designed by Indonesian engineer Tjokorda Raka Sukawati and involves the construction of the horizontal supports for the highway beside the existing road, which are then lifted and turned 90 degrees before being placed on the top of the vertical supports to form the flyover pylons. The term Sosrobahu was derived from Old Javanese; meaning "thousand shoulders".

History

Creation

One day, Tjokorda was working on his 1974 Mercedes-Benz, which he had jacked up so that the back two wheels were supported on the slippery floor of the garage where some oil had been accidentally spilled. When the car was pushed, it pivoted with the jack as the axis. He noted that, when there is no friction, it is easy to move the heaviest of objects. This event made him realize that a hydraulic pump could be used to lift heavy objects. Tjokorda conducted trials with cylinders 20 cm in diameter converted into a hydraulic lift and loaded with 80 tonnes of concrete. The weight was successfully lifted and turned slightly, but could not then be lowered as the position of the hydraulic jack had shifted. Later, Tjokorda revised the design; after testing, the hydraulic jack stayed stable even with the full weight of the concrete above it. After the trials, Tjokorda finalised his design called the LBPH (Landasan Putar Bebas Hambatan; Free Moving Platform) which consisted of two concrete discs with a diameter of 80 cm enclosed in a container. Although only 5 cm thick, the discs are capable of supporting a weight of 625 tonnes each. Between the two plates is pumped lubricating oil. A rubber seal around the edges of the plates protected against the oil escaping under the high forces experienced during the lift. The oil in the container was connected to a hydraulic pump through a small pipe.

Usages In the 1980s, during the construction of an elevated toll project above Jalan A. Yani. between Cawang and Tanjung Priok, Tjokorda had the idea of initially erecting the concrete pier shafts and then building the poured concrete pier heads in the centre lane, parallel to the existing roadway, and then raising and turning the pier heads 90 degrees into place. Though the pier heads weigh approximately 480 tonnes each. On 27 July 1988, at 22:00 GMT+7, a 440-tonne concrete was moved using a hydraulic pump that was pressurized to 78 kgf/cm² (7.6 MPa). The pier head, despite a lack of iron supports, was lifted and placed on top of the pier shaft. The longest stretch of overpass built using this technique is in Metro Manila, Philippines, at the Metro Manila Skyway. In the Philippines, 298 supports have been erected, while in Kuala Lumpur, the figure is 135.

Naming and patent In November 1989, President Soeharto of Indonesia gave the name Sosrobahu. The name was taken from a character in the Ramayana, and means 'thousand shoulders' in Old Javanese. The Indonesian patent was granted in 1995, while the Japanese patent was granted in 1992. The technology has also been used in projects in the Philippines, Malaysia, Thailand, and Singapore.

References

Further reading "Sosrobahu Bertumpu di Atas Piring", Gatra, 21 August 2004; requests payment (in Indonesian)

External links About Tjokorda Raka Sukawati and Sosrobahu; in Indonesian

Illustrations

Worked examples

Example 1 — a first encounter with Sosrobahu

Start with the simplest possible case. Write down what Sosrobahu claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Sosrobahu before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Sosrobahu ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Sosrobahu

In research: Sosrobahu appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Sosrobahu in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Sosrobahu is common in secondary-school and first-year university syllabi. It links to neighbouring topics Hydraulic tools, Indonesian inventions, Road construction, so understanding it makes those chapters shorter.
In everyday life: Look for Sosrobahu outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Sosrobahu in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Sosrobahu means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Sosrobahu out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Sosrobahu in simple terms?

Why does Sosrobahu matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Sosrobahu?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Sosrobahu.