Construction of 43 km of elevated light rail viaduct in a highly seismic region with poor soil conditions posed a challenge for design & build contractor Adhi Karya.
The alignment of the first phase of the Greater Jakarta Light Rail Transit system runs directly alongside existing highways, and in the congested urban environment of the capital this meant that space was at a premium.

  • Name of the owner & client
    Indonesian Ministry of Transportation
  • Delivery date of the project
    December 2018
  • Partners of the project
    Contractor: PT Adhi Karya
    Engineer: Systra
Jakarta Light Rail Transit System

A seismically-isolated superstructure

Innovative thinking was needed to resolve potentially conflicting conditions at this highly seismic region which also suffers from very poor soil. With no option to encroach on the highway, the contractor had to deliver an elevated LRT viaduct that would be able to operate after all but the most severe earthquakes. The conventional approach would be to use large piles and pile caps to create a sturdy substructure.

But in the light of the restricted worksite, this was not an option. Freyssinet’s response was to propose a seismically-isolated superstructure incorporating more than four thousand ISOSISM lead rubber bearings between the deck superstructure and the piers. This marked the first application of a seismic isolation system to infrastructure in Indonesia – a technology which has since become more commonplace.

 

  • 43
    Total length of elevated LRT line (km)
  • 20%
    Project cost saving through use of LRBs
  • 75%
    Earthquake force reduction
LRT-Jakarta-ISOSISM

Slimming down

These bearings enable seismic forces to be dissipated without impacting on the structure, hence the design of the piers and piled foundations could be revised to be considerably lighter and slimmer, reducing material quantities and allowing significant savings. Seismic bearing isolators are designed to be flexible during an earthquake event in order to isolate the structure. This isolation effect is represented by significant structural period shifting, reducing the earthquake impact by up to a half. In addition, the bearings have a lead core surrounded by a natural rubber compound and are capable of dampening the response of the structure by up to 29 %.

With a tight construction programme and the start of the 2018 Asian Games as a deadline, it was essential that construction was rapid and efficient. The contractor attached the bearings to the underside of the precast concrete full-span deck units before they were lifted into place, eliminating the need to work at height on the pier tops, or use temporary bearings.

Post-earthquake benefits

Freyssinet’s input enabled long-term benefits to be secured in the early design phases. The decision to install the bearings with masonry plates above and below simplifies future maintenance. The bearings can be replaced quickly and easily by unfastening a few bolts and without the need to break out any concrete – a crucial consideration in the aftermath of an earthquake.

LRT-Jakarta-Post-earthquake benefits

Freyssinet has been an excellent partner to Adhi Karya since the early stages, supporting us in defining the most efficient parameters and installation method of the LRB. To this day, the Greater Jakarta LRT project is known as the pioneer of seismically isolated structures in Indonesia, and we are proud to have started it all with Freyssinet.

Ery  
LRT Civil & Trackwork Division Manager

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