Project Outline

The Chacao Bridge, which connects Chiloé Island and mainland Chile via the Chacao Strait, is a suspension bridge with three towers and two main spans, making it the longest multi-span suspension bridge in the world with a total length of 2.75 kilometers. When completed, it will be the longest suspension bridge in South America.

The bridge deck of the Chacao Bridge is a streamlined steel box girder with a height of 3.27 meters and a width of 23.824 meters, providing a four-lane roadway, and the PPWS method was applied to the main cable. The three main towers consist of an inverted Y-shaped central tower with a height of 158.9 meters and two portal-shaped side towers with a height of 128 meters. In particular, the central tower was designed with four legs to increase the longitudinal stiffness of the bridge. The foundations of the towers were designed as bored piles, one of which is located on the reef in the center of the strait, while the other tower foundations are located on the shore.

BANDI participated in the Basic Construction Engineering (BCE) for steel deck erection in 2019, and has been responsible for the Detailed Construction Engineering (DCE) for the main cable and deck erection since 2025.

Work scope

Detailed Construction Engineering (DCE) aims to provide practical construction engineering optimized for site conditions and construction stages. The DCE scope is broadly divided into main cable erection and steel deck erection, with temporary structure design and geometry control as the core engineering services in each field.

Main Cable Erection

In the main cable erection field, BANDI is responsible for construction engineering throughout the entire main cable installation process. This includes the analysis and design of various erection ropes, the design of pylon and splay bents, PPWS erection engineering, temporary structures for the installation of clamps and hangers, and the design of the catwalk system.
The catwalk system is based on three-dimensional structural analysis, including buffeting analysis, and consists of various temporary structures such as U-frames, gallows frames, spreader beams, cross bridges, pull-down ropes, and anchoring systems. Structural safety and constructability of each component are comprehensively reviewed, while geometry control throughout saddle installation and main cable erection ensures accurate cable profiles in accordance with the design intent.

Steel Deck Erection

In the steel deck erection field, BANDI performs construction stage analysis considering structural behavior during deck installation, together with buffeting analysis, and designs various temporary structures required for erection. Temporary lugs, temporary connections, set-back systems, welding platforms, overpass bridges, and longitudinal fixation systems are reviewed and designed to ensure structural safety during erection and to support efficient construction.

Through engineering that closely reflects site conditions and construction sequences, BANDI’s DCE enables safe and efficient bridge construction.