ABSTRACT
Dirección de Vialidad Ministerio de Obras Publicás (MOP) has tendered the task of building the Chacao Bridge to the design-build consortium to Consorcio Puente Chacao (CPC) comprising Hyundai, OAS, Systra and Aas-Jacobsen. The RyO-COWI has by MOP been awarded the contract for review of the design and supervision of construction.
The Chacao bridge is the first major cable borne bridge in Chile, the project therefore provides opportunities to think out of the box rather than being constrained by an existing set of national rules and best practices.
As an exceptional bridge, the Chacao Bridge requires a special strategy for operation and maintenance compared to operation and maintenance of conventional highway bridges. This means that the design, durability and required inspection and maintenance differ from that applied to standard type of bridge elements. Furthermore, the condition for access for inspection, maintenance and re-placement are also very special for a large bridge like Chacao Bridge compared to a conventional highway bridge. In a modern bridge project, the operation and maintenance (O&M) is prepared in the design phase and implementation starts during the construction phase so that an O&M organization is ready to take over when the bridge has been commissioned.
The overall goal is to contribute to minimizing the life cycle costs of the bridge by integrating the design of an O&M system into the structural bridge design. The bridge design applies modern O&M concepts such a dehumidification of box girders and main cables, state-of-the art gantries for box girders and main cable, a tailored structural monitoring system and a number of special structural elements, which take the seismic conditions and marine environment into account.
The Chacao Bridge is a unique suspension bridge project with two major consecutive main spans, a steel box girder, concrete pylons and a composite approach bridge with concrete slabs and steel girders. The total length is 2754 m, the two main spans are 1155 m and 1055 m, and the approach bridge have 3 spans and a total length of 140 m. When completed, the bridge will be the largest suspension bridge in South America. It is located in Southern Chile in a wet marine temperate climate. The bridge has two lanes in each direction and connects the main land with the island of Chiloé.
The bridge is planned to have a service life of 100 years. The large public investment means that the Chilean society is not only concerned about the construction costs but also the benefits and costs for operating the bridge over the 100 years.
The is in line with trends of modern bridge design, which since the design of construction of the Great Belt Bridge in 1998 has had an increasing focus on the in-service aspects of the bridge to be build. These aspects involves operational risks, environment and the operation and maintenance (O&M) of the bridge. Later design-build projects such as Stonecutters, Busan-Geoje, Messina Strait Bridge, Izmit Suspension Bridge and Tappan Zee Bridges are projects where the service life design has played a major role in the design. Emphasis has been put on durability, access, inspections facilities, information gathering by use of structural health monitoring systems (SHMS), operation and maintenance system for planning and managing activities in a systematic and transparent way, and providing the MOP with an information and decision tool for short and long term planning.
