Thursday, 27 December 2018, Sibu: Construction works on the Batang Rajang Bridge or more popularly known as Durin Bridge is currently progressing steadily.
Driving along this longest bridge to be constructed under the Pan Borneo Highway Sarawak project, one can see that the two abutments of Durin Bridge and all columns of the 16 piers are now complete! Four piers are located on the river, while the balance 12 piers are located on land.
For the layman, some simple definitions may be appropriate:
- Pier - a vertical column on which the girder sits. Piers are designed to rise to the required levels above the original existing grade or river, serving to create sufficient headroom for safe flow of traffic or navigational flow below.
- Girder - a huge beam between two supporting Piers or between an Abutment and a Pier. Girders are used to support bridge decks.
- Bridge deck - is supported by girders.
- Abutment - a structure built to support the lateral pressure of earth embankment at both ends of the bridge, before the concrete bridge structure transitions itself into the earth embankment.
Today, one can see 6 of 18 incremental girders have been completed on the Sibu-end of the bridge. At the opposite Durin-end, another 7 of the total 10 girders have been completed.
One can imagine that constructing this 1.708km long bridge over the mighty Batang Rajang is not an easy feat. Specialized construction techniques have to be adopted to cater for the long spans at the free navigational flow channels underneath.
For the Batang Rajang Bridge, the cantilever segmental construction technique is employed. Once the column of each Pier is constructed along with a hammerhead structure at the top most part of the Pier, the cantilever segmental construction kicks in.
Emanating from either side of the hammerhead, the bridge deck is constructed, one segment at a time. Each segment is safely secured with sufficient pre-stressed high strength steel tendons anchored onto the hammerhead.
Casting of each cantilever segment is made possible by using a specialised travelling steel form, known as a form-traveler, custom-made for use in this bridge only.
For Batang Rajang Bridge, up to 17 segments of 4m length, will emanate from each of the four river Piers. The segments will eventually meet at the middle of the span and close up with a final segment, thus forming a whole bridge span over two piers.
Currently, out of 33 segments at Pier 11, 24 segments have been completed. The same progress has been achieved at Pier 12.
Once all segments at Pier 11 and 12 are completed, the form-traveler will be moved to repeat the same construction of cantilever segments at Pier 9 and 10. This is to ensure the completion of the major section from Pier 8 to Pier 13.
Two navigational clearances, each with a horizontal width of 110m cum vertical clearance of 20m under the bridge deck will be created. This is mandated by the Sarawak Rivers Board, making it extremely challenging to create this large span width over the mighty Batang Rajang.
When completed, Batang Rajang Bridge will rise up to about 22m from the ground. It will mirror the existing bridge with two navigation channels as noted above.
Construction works for the bridge, under WPC 07 from Bintangor Junction to Julau Junction and Sibu Airport to Sungai Kua Bridge is being undertaken by Hock Seng Lee Berhad-Dhaya Maju Infrastructure (Asia) Sdn Bhd JV with a four-year construction period.