Tuesday, 3 July 2018, Kuching: The Proof Load Test conducted for Batang Tatau Bridge last week has led to an early confirmation that the bridge which was built under the Fourth Malaysia Plan in 1979 can be maintained.
The test, conducted under the close witness of the State Public Works Department (JKRS) and other authorities was carried out to ascertain the load bearing capacity of the bridge under increased loading conditions in the future.
Simply put, Proof Load Test is a process to assess the actual capacity of the bridge.
This is ascertained through simulated loading, to ensure its capacity to cater to the eventual new design loads and higher traffic volumes.
This involves physical inspection of various elements of the bridge for durability, size and width of the bridge carriageway from a functional point of view and finally imposing the necessary physical loads onto the bridge to determine the vertical deflections obtained under the most severe load configuration conditions, all under the guiding principles of prevailing design standards and codes.
LBU Head of Construction Management Ir. Ng Chin Meng who was elated with the news asserted that with this test result, the bridge would not have to be demolished and this would save a huge cost besides giving substantial time saving advantage to the main contractor of the Sungai Arip to Bintulu Airport Junction (Works Package Contract 09) stretch.
What does it mean to maintain the existing bridge to be part of the new Pan Borneo Highway Sarawak?
The existing 2-lane 486 metres long Batang Tatau Bridge currently caters to both bound traffic – Bintulu-bound towards the north and Sibu-bound towards the south.
In the future when the 4-lane upgraded Pan Borneo Highway Sarawak is completed, two separate bridges are to be made available with 2 lanes in each direction.
Under normal circumstances, the existing bridge can be kept in place for serving 2 lanes of traffic for one direction i.e Sibu bound and a parallel new 2 lanes bridge will be constructed next to it to cater for the additional 2 lanes traffic i.e. Bintulu bound.
However, as per the original design and prompted by Sarawak River Board (SRB) regulations, the existing Batang Tatau Bridge which comprises mostly of a steel structure, would not meet the functional requirements primarily from a navigational point of view underneath.
The earlier thoughts were for the current bridge to be demolished. However, such a plan would necessitate construction of the additional 2-lane bridge to be built by the side, then demolition of the current bridge and finally a new bridge to be built at exactly the same place.
From a construction point of view, the old existing bridge which is currently functional for existing both directions traffic cannot be demolished until a new additional bridge is built next to it, paving the way for traffic from both directions to be diverted onto the new bridge.
Thereafter, demolition of the existing bridge is done, followed by the construction of a new 2-lane bridge at exactly the same place and eventually north-bound will be traffic diverted back on this bridge.
Having been given clearance by SRB to keep the current bridge, an engineering evaluation had to be made for a final decision.