True Crime-Paranormal-Conspiracy Theories Stories Part V #Wattys2023

I-35W Mississippi River Bridge

The I-35W Mississippi River bridge(officially known as Bridge 9340) was an eight-lane, steeltruss arch bridge that carried Interstate 35W across the MississippiRiver one-half mile (875 m) downstream from the Saint Anthony Fallsin Minneapolis, Minnesota, United States. The bridge opened in 1967and was Minnesota's third busiest, carrying 140,000 vehicles daily.It experienced a catastrophic failure during the evening rush hour onAugust 1, 2007, killing 13 people and injuring 145. The NTSB cited adesign flaw as the likely cause of the collapse, noting that anexcessively thin gusset plate ripped along a line of rivets, and thatadditional weight on the bridge at the time contributed to thecatastrophic failure.

Help came immediately from mutual aidin the seven-county Minneapolis–Saint Paul metropolitan area andemergency response personnel, charities, and volunteers. Within a fewdays of the collapse, the Minnesota Department of Transportation(Mn/DOT) planned its replacement with the I-35W Saint Anthony FallsBridge. Construction on the replacement bridge was completed quickly,with it opening on September 18, 2008.

Location and site history

The bridge was located in Minneapolis,Minnesota's largest city and connected the neighborhoods of DowntownEast and Marcy-Holmes. The south abutment was northeast of the HubertH. Humphrey Metrodome, and the north abutment was northwest of theUniversity of Minnesota East Bank campus. The bridge was thesoutheastern boundary of the "Mississippi Mile"downtown riverfront parkland. Downstream is the 10th Avenue Bridge,once known as the Cedar Avenue Bridge. Immediately upstream is theSaint Anthony Falls lower lock and dam. The first bridge upstream isthe historic Stone Arch Bridge, built for the Great Northern Railwayand now used for bicycle and pedestrian traffic.

The north foundation pier of the bridgewas near a hydroelectric plant that was razed in 1988. The southabutment was in an area polluted by a coal gas processing plant and afacility for storing and processing petroleum products. These useseffectively created a toxic waste site under the bridge, leading to alawsuit and the removal of the contaminated soil. No relationship hasbeen claimed between these previous uses and the bridge failure.

Design and construction

The bridge, officially designated"Bridge 9340", was designed by Sverdrup & Parcelto 1961 AASHTO (American Association of State Highway Officials, nowAmerican Association of State Highway and Transportation Officials)standard specifications. The construction contracts, worth in totalmore than $5.2 million at the time, were initially offered to HurConInc. and Industrial Construction Company. HurCon expressed concernabout 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 in1964 and the structure was completed and opened to traffic in 1967during an era of large-scale projects to build the Twin Citiesfreeway system. When the bridge fell, it was still the most recentriver crossing built on a new site in Minneapolis. After the buildingboom ebbed during the 1970s, infrastructure management shifted towardinspection and maintenance.

The bridge's fourteen spans extended1,907 feet (580 m) long. The three main spans were of deck trussconstruction while all but two of the eleven approach spans weresteel multi-girder construction, the two exceptions being concreteslab construction. The piers were not built in the navigationchannel; instead, the center span of the bridge consisted of a single458-foot (140 m) steel arched truss over the 390-foot (119 m)channel. The two support piers for the main trusses, each with twoload-bearing concrete pylons at either side of the center main span,were located on opposite banks of the river. The center span wasconnected to the north and south approaches by shorter spans formedby the same main trusses. Each was 266 feet (81 m) in length, and wasconnected to the approach spans by a 38-foot (11.6 m) cantilever. Thetwo 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 (11m) at mid-span on the central span and 30 feet (9 m) deep at theouter ends of the adjoining spans. At the top of the main trusseswere the deck trusses, 12 feet (3.6 m) in depth and integral with themain trusses. The transverse deck beams, part of the deck truss,rested on top of the main trusses. These deck beams supportedlongitudinal deck stringers 27 inches (69 cm) in depth, andreinforced-concrete pavement. The deck was 113 ft 4 in (34.5 m) inbreadth and was split longitudinally. It had transverse expansionjoints at the centers and ends of each of the three main spans. Theroadway deck was approximately 115 feet (35 m) above the water level.