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| Major Design Change Changed Collapsed Bridge's Cost, Schedule |
| 2018-03-21 |
| Ay-Pee. Grains of salt required. The lawyers have shut everyone up [USNews] Construction of the pedestrian bridge that collapsed and killed six people in the Miami area was behind schedule and millions over budget, in part because of a key change in the design and placement of one of its support towers. Documents obtained by The Associated Press through a public-records request show that the Florida Department of Transportation in October 2016 advised Florida International University and its contractors to move one of the bridge's main support structures 11 feet (3 meters) north to the edge of a canal, widening the gap between the crossing's end supports and requiring some new structural design. The span's signature, 109-foot-tall (33-meter-tall) pylon was to be built atop a base at the span's northern end. It was designed for basic support and to contribute to the aesthetics of the bridge U.S. Transportation Secretary Elaine Chao has ordered her department's inspector general to conduct an audit of the bridge, according to a news release Tuesday from the U.S. Department of Transportation. The agency awarded millions of dollars to the project. so "Buy America" provisions for the steel (rebar, tension strands and anchorages) were in place. No foreign steel allowed above 0.5% It is still unclear if the design change contributed to the failure. But emails between the school, contractors, Sweetwater city officials and permitting agencies show a project that was behind schedule, which had officials worried that further delays could jeopardize the federal funding. When the bridge collapsed, the project was already running about $2.6 million over its $9.4 million initial budget, cost-tracking documents from February show. Originally scheduled to be completed in July, the finish date had been pushed back to January 2019 Difficulties began in late 2016, when the Florida Department of Transportation emailed project officials saying they wanted more room to allow for future widening of the U.S. highway under the bridge, according to the documents. The new position of the tower would be on the north side between the road and the canal. "This ... places the current location of the pylon in conflict with the extra travel lane and would require bridge design modifications," Alfred Reyna, a transportation department employee working on the bridge project, wrote in an email. After weeks of back and forth, it was decided to move the pylon 11 feet to the north, sitting near the edge of the canal. According to documents, initial costs for the new design were $204,540, with another $402,723 for construction changes. The final cost was not divulged. "The city attorney is advising us not to speak about anything to do with the bridge," said Sandra Antonio, a spokeswoman for the city of Sweetwater, which was working with FIU. The tower was to be located on the Sweetwater side. Don Silver, a spokesman for Munilla Construction Management, or MCM, the Miami-based construction management firm that won the bridge contract, said the National Transportation Safety Board forbade engineers or contractors from talking about the project pending its investigation. MCM collaborated with Tallahassee-based FIGG Bridge Design on the bridge project, which also declined comment. A spokeswoman for FIU, Maydel Santana, declined comment on the pylon redesign, but did confirm Tuesday that the bridge was expected to be completed early in 2019 and the grant ran out on Sept. 30, 2019. She also said the school was cooperating with the NTSB's investigation. |
| Posted by:Frank G |
| #4 I do this for a living and I still don't know enough to say confidently why it failed. One box was checked off - the materials were all US-Origin for steel, as should the cement (just because it's cheaper), so not likely a sleazy material swap-out |
| Posted by: Frank G 2018-03-21 19:56 |
| #3 garth, As I understand it, the suspension cables were only for show. They didn't carry any load. The temporary support on the end that failed was supposed to be under the single truss at that end. Instead, it was placed further towards the middle leaving that end to sag. Concrete is great under compression but sucks wind under Tension. The tension bars were already stressed to the limit when they tried to tighten them and it soon failed. |
| Posted by: Omoter Gligum2747 2018-03-21 16:49 |
| #2 This was interesting...why the bridge collapsed. https://youtu.be/ioC61QW7SHQ |
| Posted by: BrerRabbit 2018-03-21 16:48 |
| #1 so apparently, this was supposed to be a cable stayed bridge with the support tower on one of the ends instead of in the center of the span and also they decided to place the deck structure before they built the support tower ??? |
| Posted by: lord garth 2018-03-21 16:10 |