page_title: Extradosed bridge
section_title: Bolivia
hierarchical_section_title: Extradosed bridge / By country / Bolivia
caption_attribution_description: Puentes Trillizos
context_page_description: An extradosed bridge employs a structure that combines the main elements of both a prestressed box girder bridge and a cable-stayed bridge. The name comes from the word extrados, the exterior or upper curve of an arch, and refers to how the "stay cables" on an extradosed bridge are not considered as such in the design, but are instead treated as external prestressing tendons deviating upward from the deck. In this concept, they remain part of the main bridge superstructure.
  Compared to a cable-stayed or cantilever-girder bridge of comparable span, an extradosed bridge uses much shorter stay-towers or pylons than the cable-stayed bridge, and a significantly shallower deck/girder structure than used on the girder bridge. This arrangement results in the typical extradosed "look" of a fan of low, shallow-angle stay cables, usually with a pronounced "open window" region extending from the sides of each tower.
  The extradosal bridge form is mostly suited to medium-length spans between 100 m and 250 m, and over fifty such bridges had been constructed around the world as of 2012.
context_section_description: The Triplets are the first three extradosed concrete bridges in Bolivia. The construction of a beltway allowing traffic decongestion in the city of La Paz was completed in 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 the Triplets. All three-span structures are made of concrete, with maximum span of 372 feet, featuring extradosed pre-stressed concrete. The structures are built using balanced cantilever segmental construction. The elevation of the bridges reaches heights between 130 and 197 ft above the bottom of the valley, which made a cable-stayed bridge option, with pylons higher than 82 ft above the deck, inappropriate for the site. Therefore, it was proposed an extradosed bridge type, which reduces the height of the pylon, and a single plane of stays to allow a more transparent view. The bridges were designed by PEDELTA.
caption: Puentes Trillizos: The Triplets bridges
exif: {"Image ImageWidth": "4288", "Image ImageLength": "2848", "Image BitsPerSample": "[8, 8, 8]", "Image PhotometricInterpretation": "2", "Image Make": "NIKON CORPORATION", "Image Model": "NIKON D90", "Image Orientation": "Horizontal (normal)", "Image SamplesPerPixel": "3", "Image XResolution": "100", "Image YResolution": "100", "Image ResolutionUnit": "Pixels/Inch", "Image Software": "Adobe Photoshop CC 2015 (Windows)", "Image DateTime": "2017:05:05 16:43:32", "Image YCbCrPositioning": "Co-sited", "Image ExifOffset": "312", "GPS GPSVersionID": "[2, 2, 0, 0]", "Image GPSInfo": "1008", "Thumbnail Compression": "JPEG (old-style)", "Thumbnail XResolution": "72", "Thumbnail YResolution": "72", "Thumbnail ResolutionUnit": "Pixels/Inch", "Thumbnail JPEGInterchangeFormat": "1122", "Thumbnail JPEGInterchangeFormatLength": "4320", "EXIF ExposureTime": "2", "EXIF FNumber": "28/5", "EXIF ExposureProgram": "Manual", "EXIF ISOSpeedRatings": "200", "EXIF ExifVersion": "0221", "EXIF DateTimeOriginal": "2014:01:30 20:45:38", "EXIF DateTimeDigitized": "2014:01:30 20:45:38", "EXIF ComponentsConfiguration": "YCbCr", "EXIF CompressedBitsPerPixel": "2", "EXIF ShutterSpeedValue": "-1", "EXIF ApertureValue": "2485427/500000", "EXIF ExposureBiasValue": "0", "EXIF MaxApertureValue": "41/10", "EXIF MeteringMode": "Pattern", "EXIF LightSource": "Unknown", "EXIF Flash": "Flash did not fire", "EXIF FocalLength": "32", "EXIF SubSecTime": "00", "EXIF SubSecTimeOriginal": "00", "EXIF SubSecTimeDigitized": "00", "EXIF FlashPixVersion": "0100", "EXIF ColorSpace": "sRGB", "EXIF ExifImageWidth": "1403", "EXIF ExifImageLength": "932", "Interoperability InteroperabilityIndex": "R98", "Interoperability InteroperabilityVersion": "[48, 49, 48, 48]", "EXIF InteroperabilityOffset": "976", "EXIF SensingMethod": "One-chip color area", "EXIF FileSource": "Digital Camera", "EXIF SceneType": "Directly Photographed", "EXIF CVAPattern": "[0, 2, 0, 2, 1, 2, 0, 1]", "EXIF CustomRendered": "Normal", "EXIF ExposureMode": "Manual Exposure", "EXIF WhiteBalance": "Auto", "EXIF DigitalZoomRatio": "1", "EXIF FocalLengthIn35mmFilm": "48", "EXIF SceneCaptureType": "Standard", "EXIF GainControl": "None", "EXIF Contrast": "Normal", "EXIF Saturation": "Normal", "EXIF Sharpness": "Normal", "EXIF SubjectDistanceRange": "0"}