The construction of a beltway allowing traffic decongestion in the city of La Paz, Bolivia, has been completed (2010). The new elevated road crosses three parallel valleys with signature bridges. These three consecutive bridges have similar features and as a result are called “Trillizos” in Spanish. All three-span structures are made of concrete, with a maximum span of 113.5 m, featuring extradosed pre-stressed deck.
Extradosed bridges are a cost-effective cable supported bridge type. This project was awarded with the Eugene C. Figg Medal at the IBC 2012, Pittsburgh, PA.
Design was carried out meeting the AASHTO LRFD requirements.
The structures are built using balanced cantilever segmental construction. The elevation of the three bridges reaches heights between 40 m and 60 m above the bottom of the valley, which made a cable-stayed bridge option, with pylons higher than 25 m above the deck, inappropriate for the site. Therefore, a typology of extradosed bridge was proposed, which reduces the height of the pylon. The design includes a single plane of stays for a more transparent view. At the same time, it implies the introduction of a new and modern typology in Latin America.
Sobrino, J.A.; Bridges “The Triplets” in La Paz, Bolivia. (in Spanish, Puentes Trillizos
en La Paz, Bolivia), Cauce 2000: Revista de la ingeniería civil, (ISSN-0212-761X), pp 56-63, September 2010.
Sobrino J.A.; Trillizos Bridges (The Triplets) in La Paz, Bolivia. Proceedings of the
Large Structures and Infrastructures for Environmentally Constrained and Urbanized Areas IABSE Symposium. Venice, September, 2010.