Sosrobahu: Revolutionizing Urban Infrastructure with a 90-Degree Twist

Sosrobahu: Revolutionizing Urban Infrastructure with a 90-Degree Twist

In the era under Suharto's presidency, Indonesia embarked on a bold endeavor to reshape transportation dynamics on Java Island. This ambitious undertaking encompassed the construction of novel road networks, featuring both ground-level highways and elevated overpasses. However, these innovative urban projects often encountered formidable challenges due to the bustling traffic below.

Enter Sosrobahu — a visionary innovation engineered to directly confront urban obstacles. The Sosrobahu method revolutionized the landscape of elevated bridge construction. It introduced a groundbreaking concept: the ability for concrete arms to pivot by 90 degrees post-construction, seamlessly aligning with the underlying road. This ingenious adaptation served to significantly mitigate traffic disruptions and ensure uninterrupted daily life during the construction phase.

The Ir. Wiyoto Wiyono Toll Road, the first toll road to undergo a trial using the Sosrobahu technique. ©️BPJT Kementerian PUPR RI

The brilliant mind behind Sosrobahu was Dr. Ir. Tjokorda Raka Sukawati, an Indonesian engineer from Bali who conceived the idea while engaged in a project for PT Hutama Karya (Persero). This endeavor aimed to materialize the Ir. Wiyoto Wiyono Toll Road in Jakarta, bridging Cawang with Tanjungpriok. Significantly, this initiative spanned Jalan Ahmad Yani, a thoroughfare renowned for its heavy traffic congestion. In Indonesia, Sosrobahu technique has been embraced in numerous substantial national projects following the Ir. Wiyoto Wiyono Toll Road's success, including the Bekasi–Cawang–Kampung Melayu Toll Road and the Sheikh Mohamed bin Zayed Skyway.

The journey of Sosrobahu commenced with the erection of concrete pillars tracing the designated route. Subsequently, intricate concrete arms were meticulously crafted, forming an elevated roadbed nestled between tightly-woven lanes and parallel to the existing thoroughfare. The transformative twist unfolded in the subsequent phase. Upon interconnecting these concrete arms, the Sosrobahu technique came into play, deftly rotating the arms by 90 degrees. This groundbreaking pivot facilitated the harmonious alignment of the elevated roadbed with the cityscape, effectively circumventing traffic disruptions without the necessity of unwieldy scaffolding.

In the realm of technical design, Tjokorda harnessed the core principles of Pascal's Law, which dictates that fluid pressure exerts itself uniformly in all directions. By amalgamating this law with a medley of variables, the Sukawati Formula, named in honor of its originator, was born. The chosen medium, mineral oil, was channelled through a hydraulic system controlled by a pump. Hydraulic pressure guided the displacement of oil between two iron discs positioned beneath the concrete arms. The application of pressure culminated in the precise elevation and rotation of the concrete arms in line with the preconceived plan.

This innovative methodology transformed the process of rotating substantial concrete arms into a seamlessly efficient feat. The pinnacle of the Sosrobahu innovation manifested as a frictionless rotating platform, endowed with the capacity to bear considerable loads. This innovation played a pivotal role in the development of elevated roads, without causing disruption to the traffic flow below.

The Sheikh Mohamed bin Zayed Skyway, an elevated toll road with congested traffic underneath and infrastructure projects to its north and south, was constructed using the Sosrobahu technique. ©️Getty Images/Bay Ismoyo

The impact of this breakthrough extended far beyond Indonesia's boundaries, influencing urban development across Southeast Asia. The scope of this technology transcended national lines, leaving an indelible mark in the Philippines, Malaysia, Thailand, and Singapore. The most extensive elevated road segment constructed using this ingenious methodology finds its home in Metro Manila, specifically within the city's southern Metro Manila Skyway. The Philippines witnessed the installation of 298 supports, while Kuala Lumpur followed suit with 135. President Fidel V. Ramos of the Philippines eloquently lauded this innovation, aptly recognizing it as, "This is an Indonesian invention, but it is also an ASEAN invention."

Rafa Sukoco

An Indonesian, born into a multiethnic family, with a passion for traveling, culinary experiences, and delving into history and religion. Enjoying life through listening and sharing stories.
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