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In order to accommodate the expansion of Batam Island as a free trade industrial area, a master plan put in place to connect Batam Island to 5 (five) neighbouring islands, thus enlarging the Batam are to nearly triple its present size and to 15% greater than Singapore.

The Barelang bridge projects consist of 6 (six) bridges including a cable-stayed bridge, two balanced cantilever bridges, two precast segmental bridges, and an arch bridge. The largest of the bridges constructed is the cable-stayed structure which links Batam with Tonton Island. It is a three-span, symmetrical cable-stayed bridge, with a total length of 642 m and a main span of 350 m built of cast-in-place concrete.

The Pylons

It has two “A”-shaped pylons extending 118 m above the pile caps which are supported on bored piles. The navigation clereances is 39 m. The pylon legs have a rectangular hollow cross section of 3 m x 5 m x 4.2 m, and the two inclined legs are connected with cross beams below deck level and below the pylon head. It was originally intended to construct the pylon head using steel but the design was later modified for a concerete structure.

The pylon legs were built with climbforms in typical lifts of 4 m and the two individual climbforms for each leg of a pylon were joined into one unit for the pylon leg. The formwork area of one climform is 94 m2 and the typical concrete volume per lift for one leg was between 30 and 40 m3, and between 80 and 115 m3 in the pylon head.

The Deck

The 22 m-wide deck is straight in plan and covers a total surface area of 13,800 m2, consisting of a 280 mm slab sitting on transverse beams spaced at 4 m intervals. Two main edge girders of 2 m x 2 m provide the longitudinal support for the deck, with the stay cables anchored in the edge girders at 12 m intervals.

The deck is rigidly supported at the abutments but floating with transverse restrains only, at the pylon. During construction the dock was temporarily restrained longitudinally at the pylon.

The 28 m pier table was built on falsework supported from the pile cap with the first four stay cables subsequently holding the pier table spanning 24 m. The pier table was fixed for lateral and longitudinal movements during construction of the pylon.

The two 146 m long side spans of the deck were constructed on up to 30 m high falsework. Segments of 12 m long were cast-in-palce typically two cycles ahead of the main span. Three sets of falsework were used and moved alternately ahead. The entire cross section of the 12 m segments was done in one pour.

The main spam was built in balanced cantilever construction using form-travellers. The form traveller allows pouring of edge bemas in the front part and pouring of the deck and cross beams in the rear part. The average cycle time achieved is said to have been 15 days for placing a total of 190 m3 of concrete, 26 t of rebar and 5 t of post-tensioning.

Stay Cables

The project included a total of 986 t of stay cables, and cable sizes range from 31 up to 91 x 0.6 inch strands. The cables have lengths between 61 m and 187 m and are spaced at 12 m intervals in the deck edge girders.

The VSL Stay Cable System SSI 200 was used, and this consists of greased and sheathed monostrands, individually placed inside HDPE guide tubes. The entire bundle of monostrands and guide tubes in encapsulated by a thick wall of HDPE pipe.

Stay cable anchorage including guide tubes and grouting were prefabricated on site. With the means available on site it was decided to prefabricat the free stay length including strands, preassembled with the anchorages in an area located behind the abutmnets, and lift the stays as a single element in place.

(Source : PT VSL Indonesia brochure, downloaded from internet)

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