The Sosrobahu: A Thousand Shoulders

The ambitious South Metro Manila Skyway Project (SMMSP) aims to create an infrastructure that makes vehicular travel between Metro Manila and the southern neighboring communities and provinces faster, safer, more comfortable.

In undertaking SMMSP,  which primarily involves the construction of elevated expressway from Buendia in Makati City to Alabang in Muntinlupa City,  Citra Metro Manila Tollways Corporation (CMMTC) uses the “sosrobahu,”  the unique technology invented by an Indonesian engineer,  Tjokorda Raka Sukawati, and perfected by Hutama-Karya, a respectable construction company in Indonesia, where Engr. Tjokorda was a former director.

The “sosrobahu” which means “a thousand shoulder,”  is a frictionless rotating device that allows the construction of elevated roads without major disruption on the flow of traffic on the ground.  It has been extensively tested and used in the construction of the Cawang-Tanjung Priok elevated expressway in Indonesia, where the first actual pierhead rotation was inaugurated by then President Suharto on July 7 , 1988.  This device was since used in many other major viaduct projects in Indonesia.

In a conventional cast-in-place concrete pierhead construction,  the scaffoldings occupy a major portion of the existing roadway which can cause major disruption in traffic flow thereby adversely affecting hundreds of thousands of motorists and commuters.

The most unique construction methology adopted in SMMSP is the rotation of the pierhead on top of a single column where the “sosrobahu” is embedded between the column and the pierhead being constructed on top of the column on the median initially parallel to the road.

This methology is a very useful traffic management tool for the construction of the Skyway Project along the busy South Luzon Expressway as it allows traffic to flow at all times along the expressway below and avoid extensive rerouting measures during the construction of the massive pierheads since the scaffoldings are made to occupy the road median only.  Once the pierhead concrete reaches its required strength,  it is rotated is constructed to its final position perpendicular to the expressway below and locked to the column by means of U-shaped post-tensioned cables and anchor bars, ready to support the elevated roadway.