P995.038M Agas-Agas Bridge Construction Is Nearing Completion

Maasin City, Southern Leyte – The ongoing construction which started sometime in 2007 of the P995,037,013.61 Agas-Agas bridge with a current accomplishment of 78.63% incurring a positive slippage of 4.39%,as of February 2009, was estimated to be completed before the end of this year.

The contract under Contract Package V signed between the Philippines and Japanese Governments has its source of funds from JBIC and implemented by the Philippines-Japan Highway Loan Project Office.

A young lady Engineer who works with the project and speaks on condition of anonymity, informed that the Agas-Agas Bridge when completed would be 350 linear meters long that consist of 3-span balanced Cantilever -type Continuous Pre-stressed Concrete Box Girder (CPCBG).This is strongly connected to 2 Pier Heads of 75 meters height and 73.5 meter height respectively on 1.5 meter diameter bored piles foundation.

She said that the bridge works also include the rehabilitation/improvement and widening of 1.5 kms road for pavement concreting, improvement of road drainage system and construction of slope protection and other structures.

At the start of the project, the Engineer said, the major items of works were done phase by phase: 1)Access road construction-in going down 75 meters below to Pier1 and Pier 2 (columns- supports) location; 2) Bored Piles Construction-drilled on hard rocks. Piles have 1.5 meter diameter with a variable depths. A sophisticated bored pile equipment was used that can drill up to 7000psi rock strength; 3) Pile Cap Construction-huge size or part of substructures that will unify the piles drilled to support the bridge. The volume of concrete required for pier one and pier 2 are 1,225 cu.m. and 1,969 cu.m. respectively. 4) Pier Column Construction-Columns of 2 Piers have heights of 75meters and73.5meters for piers 1 and 2 respectively. The average volume of concrete required per lift is 70 cu.m. to 100 cu.m. This bridge has the tallest pier column ever built in the Philippines: 5)Pier Head Construction-Constructed by steel bracket support system and mainly supported by the frictional force created by applying a pre-stress on the PC bar tying the bracket to the column. The pier head was casted into 3 lifts considering the difficulties of works and huge amount of concrete required. It has a total volume of 428 cu.m. for pier1 and 521cu.m. for pier 2 and with a total weight of1,069 tons and 1,301 tons for pier 1 and 2 respectively; 6) Balanced Cantilever Type(PCBG) Construction-Once the Pier head construction is finished,wagen or form traveler will be installed to both sides of Pier Head to start the construction of the Pre-stressed Concrete Box Girder(PCBG).The PCBG are divided into blocks which are almost symmetrical in shape and weight. Opposite blocks should be constructed simultaneously. The volume of concrete required per block ranges from 70cu.m. to 120 cu.m. 7) End Segment Construction-End-span construction will start if the concerned abutment support is completed, and the PCBG) from the respective Pier going to the abutment is 50% accomplished.. The end-span will be constructed by conventional supporting method. The total weight of this structure is 400 tons supported by temporary steel structures; Post Tensioning-The special works applied to this project make the construction of this balanced cantilever bridge successful. For every block casts, an average of 2 to 4 cables was stressed to support the blocks and its preceding block. A 12 number to 15.2 diameters of pre-stressing steel per cable was being stressed up to 220 to 224 tons/cable.

Informative Revelations

The Engineer further revealed that the tons of huge cables used in the construction of the 350 meters bridge will provide as its supportive strength and for durability. This kind of material is indispensably important, she said, so that if the bridge will have a heavy load of vehicles caused by a heavy traffic, it will not sag.

She said that the 2 tall pier heads are hollow(meaning no pouring of cement, sand and gravel mixture to solidify the pier heads) But its hollowness were filled up with a series of big steel bars measuring 15 in diameter, while its steel clips were about 12 diameter. As seen by this writer on his way from Tacloban to Maasin en route to Mahaplag, Leyte recently, the constructed bridge has only a few feet gap between its 2 ends before it can fully be connected. “The principle of having hollow pier heads is derived from a bamboo tree. A bamboo tree has grooves between hollows. When it will be blown by the strong wind, it will not break but only bend”, the young Engineer explained. “By analogy the hollowed pier heads if there’s an earthquake will not just break easily but would “bend” with the support of big steel bars placed in series inside the hollow. This bridge is located near the faultline”.

The female Engineer disclosed that every day there’s a survey on the bridge’s alignment before any work could start since sustaining its proper alignment is a technical SOP in constructing a strong and standard bridge. When it will be completed and the 2 abutments will finally be constructed, she said, construction of baluster- type of railings will follow. She said that the recipient of this bridge upon completion is the Dept of Public Works and Highways, a government agency in-charged in the building and maintenance of roads and bridges.

With the exception of the San Juanico Bridge that connects the islands of Leyte and Samar, the Agas-Agas Bridge in brgy. Kahupian,Sogod,Southern Leyte has the tallest deck elevation and the longest PCBG span bridge in the Philippines without stay cable, she divulged, adding that they are going to construct in the Sogod part abutment a parking area, public toilet and a quarter for travelers.

Two viewing decks on 75-meter pier head will also be constructed, she said, and to install bridge lights if the Katahira Consultancy, the office that design the bridge, will approve their proposal.

The project, it was learned, was handled and supervised by contractor Sumitomo Mitsui Construction Co.Ltd and subcontracted by experienced Abad and APM Construction firms. Project Manager is Engr. Hiromi Chi Tatsuzawa.The project is manned by both Japanese and Filipino standard design Engineers, site Engineers and other types of Engineers involved in the bridge constructions.

The Agas-Agas Bridge, when fully finished, has the great potentiality of becoming a tourist attraction in this part of region 8.The view of the mountainous terrain with lush vegetation and trees in its surrounding area needs to be protected and preserved. Cutting of trees should not be allowed, burning of trash and wastes should be banned and throwing of any kind of garbage anywhere must be strictly prohibited. Trash cans must be provided in the parking area and near the bridge. (Quirico M.. Gorpido, Jr.)

About the Contributor:

Mr. Quirico M. Gorpido Jr was an erstwhile Correspondent/Contributor to the following weeklies and dailies: Tacloban-based regional weekly a 33-year-old The Reporter for many years(now defunct), a Cebu-based weekly The Visayan Express(now defunct),Cebu-based daily The Freeman(1994-1998) now a sister publication of The Philippine Star, Maasin-based weekly The Southern Leyte Times for three years, Tacloban-based daily The Leyte Samar Daily Express(2000-2001), Cebu-based daily the Cebu Daily News(2002-2003), Tacloban-based weekly 7-year-old Tribune(2003-2007).