Thursday, 9 May 2019, Sibu: One of the spans at Batang Rajang Bridge or more popularly known as Durin Bridge has been successfully “stitched” yesterday. Five out of 17 spans of this box girder bridge need to undergo the stitching process to close the segment in between two adjoining piers.
The process is literally a designated construction sequence to close the last segment, or gap, between the edges of two opposite cantilever segments (or between the end of an incremental girder and the end of a cantilever segment) to form a complete continuous span.
From the river pier (Pier 12), the bridge structure is constructed using the cantilever segmental construction method towards the land pier (Pier 13). From the land side, the bridge structure is constructed using the incremental girder method and is carefully pulled up towards the river pier (Pier 12). When the two ends meet, it is joined together to form a monolithic bridge, with the top deck meant for the highway carriageways.
The elated LBU Project Manager for Bintangor Junction-Julau Junction and Sibu Airport-Sungai Kua Bridge (Works Package 07) Mr Liew Hin Leong described witnessing both ends being stitched together with the help of the closing segment as giving the project team “the most wonderful and ecstatic feeling”. The precision engineering construction method, he further said, and meticulous effort put in over many months had finally come to fruition perfectly.
The stitching process is under way for the remaining four spans. The whole process is expected to be completed by the end of the year, which means the construction work on this 1.708km bridge, the longest in the whole of Pan Borneo Highway Sarawak project, has reached another significant milestone!
When the stitching process is completed, the construction work can move on to do the parapet wall and road furniture.
Four stages will be involved in the process to complete casting of each one of the five closing segments (stitching). The first stage is to install and stress the horizontal cross bracings.
This will be followed by Stage 2 which is to adjust the vertical alignment between the ends of the two opposing cantilever segments by using clamping trusses and carefully pulling them to match the level at the top.
Many similar fine adjustments have been carried out earlier during the stressing process of each completed segment (a total of 34 segments at Pier No. 12) before it arrives at this stage of closing segment. Meticulous, careful and painstaking engineering work had already gone into the construction process, which is a distinctive characteristic of this type of intricate and precision construction.
Once this is done to the satisfaction of the Supervision Consultants, it is time to move on to Stage 3 to install the closing segment formwork to fix the closing segment in its rightful place, along with other necessary reinforcements, etc.
Finally, Stage 4 involves casting (using very high strength concrete) of the closing segment. It will be followed by the stressing of the bottom tendons of this closing segment upon the concrete maturing to the required strength.
As for the configuration of the bridge in consideration of its navigational capabilities underneath, the bridge will see two navigational clearances, each with a horizontal width of 110m and a vertical clearance of 20m under the bridge soffit created. This is mandated by the Sarawak Rivers Board, making it truly 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 approach ground. It will mirror the existing bridge with two navigation channels as noted above.
The main contractor for Works Package 07 is Hock Seng Lee Berhad-Dhaya Maju Infrastructure (Asia) JV Sdn Bhd.