page_title: I-35W Mississippi River bridge
section_title: Design and construction
hierarchical_section_title: I-35W Mississippi River bridge / Design and construction
caption_attribution_description: The south end of the w:en:I-35W Mississippi River Bridge, taken from the east side of the bridge. This photo was taken on 2006-05-06, well before its collapse on 2007-08-01.
context_page_description: The I-35W Mississippi River bridge was an eight-lane, steel truss arch bridge that carried Interstate 35W across the Saint Anthony Falls of the Mississippi River in Minneapolis, Minnesota, United States. The bridge opened in 1967 and was Minnesota's third busiest, carrying 140,000 vehicles daily. It had a catastrophic failure during the evening rush hour on August 1, 2007, killing 13 people and injuring 145. The NTSB cited a design flaw as the likely cause of the collapse, noting that a too-thin gusset plate ripped along a line of rivets, and additional weight on the bridge at the time contributed to the catastrophic failure.
  Help came immediately from mutual aid in the seven-county Minneapolis–Saint Paul metropolitan area and emergency response personnel, charities, and volunteers. Within a few days of the collapse, the Minnesota Department of Transportation planned its replacement with the I-35W Saint Anthony Falls Bridge. Construction on the replacement bridge completed quickly, opening on September 18, 2008.
context_section_description: The bridge, officially designated "Bridge 9340", was designed by Sverdrup & Parcel to 1961 AASHTO (American Association of State Highway Officials, now American Association of State Highway and Transportation Officials) standard specifications. The construction contracts, worth in total more than US$5.2 million at the time, were initially offered to HurCon Inc. and Industrial Construction Company. HurCon expressed concern about the project, reporting that one portion of the bridge, Pier 6, could not be built as planned. After failed discussions with MnDOT, HurCon backed out of the project altogether.
  Construction on the bridge began in 1964 and the structure was completed and opened to traffic in 1967 during an era of large-scale projects to build the Twin Cities freeway system. When the bridge fell, it was still the most recent river crossing built on a new site in Minneapolis. After the building boom ebbed during the 1970s, infrastructure management shifted toward inspection and maintenance.
  The bridge's fourteen spans extended 1,907 feet (580 m) long. The three main spans were of deck truss construction while all but two of the eleven approach spans were steel multi-girder construction, the two exceptions being concrete slab construction. The piers were not built in the navigation channel; instead, the center span of the bridge consisted of a single 458-foot (140 m) steel arched truss over the 390-foot (119 m) channel. The two support piers for the main trusses, each with two load-bearing concrete pylons at either side of the center main span, were located on opposite banks of the river. The center span was connected to the north and south approaches by shorter spans formed by the same main trusses. Each was 266 feet (81 m) in length, and was connected to the approach spans by a 38-foot (11.6 m) cantilever. The two main trusses, one on either side, ranged in depth from 60 feet (18.3 m) above their pier and concrete pylon supports, to 36 feet (11 m) at midspan on the central span and 30 feet (9 m) deep at the outer ends of the adjoining spans. At the top of the main trusses were the deck trusses, 12 feet (3.6 m) in depth and integral with the main trusses. The transverse deck beams, part of the deck truss, rested on top of the main trusses. These deck beams supported longitudinal deck stringers 27 inches (69 cm) in depth, and reinforced-concrete pavement. The deck was 113 ft 4 in (34.5 m) in breadth and was split longitudinally. It had transverse expansion joints at the centers and ends of each of the three main spans. The roadway deck was approximately 115 feet (35 m) above the water level.
caption: South end of I-35W bridge as seen from West River Parkway
exif: {"Image Make": "Canon", "Image Model": "Canon PowerShot S200", "Image Orientation": "Horizontal (normal)", "Image XResolution": "180", "Image YResolution": "180", "Image ResolutionUnit": "Pixels/Inch", "Image DateTime": "2006:05:06 16:50:37", "Image YCbCrPositioning": "Centered", "Image ExifOffset": "196", "Thumbnail Compression": "JPEG (old-style)", "Thumbnail XResolution": "180", "Thumbnail YResolution": "180", "Thumbnail ResolutionUnit": "Pixels/Inch", "Thumbnail JPEGInterchangeFormat": "2036", "Thumbnail JPEGInterchangeFormatLength": "4760", "EXIF ExposureTime": "1/250", "EXIF FNumber": "71/10", "EXIF ExifVersion": "0220", "EXIF DateTimeOriginal": "2006:05:06 16:50:37", "EXIF DateTimeDigitized": "2006:05:06 16:50:37", "EXIF ComponentsConfiguration": "YCbCr", "EXIF CompressedBitsPerPixel": "3", "EXIF ShutterSpeedValue": "255/32", "EXIF ApertureValue": "46331/8192", "EXIF ExposureBiasValue": "0", "EXIF MaxApertureValue": "97349/32768", "EXIF MeteringMode": "Pattern", "EXIF Flash": "Flash did not fire, auto mode", "EXIF FocalLength": "173/32", "EXIF FlashPixVersion": "0100", "EXIF ColorSpace": "sRGB", "EXIF ExifImageWidth": "1600", "EXIF ExifImageLength": "1200", "Interoperability InteroperabilityIndex": "R98", "Interoperability InteroperabilityVersion": "[48, 49, 48, 48]", "Interoperability RelatedImageWidth": "1600", "Interoperability RelatedImageLength": "1200", "EXIF InteroperabilityOffset": "1412", "EXIF FocalPlaneXResolution": "800000/103", "EXIF FocalPlaneYResolution": "240000/31", "EXIF FocalPlaneResolutionUnit": "2", "EXIF SensingMethod": "One-chip color area", "EXIF FileSource": "Digital Camera", "EXIF CustomRendered": "Normal", "EXIF ExposureMode": "Auto Exposure", "EXIF WhiteBalance": "Auto", "EXIF DigitalZoomRatio": "1", "EXIF SceneCaptureType": "Standard"}