“I think we are all lucky that there was not a collapse.” :runaway:
https://www.sfchronicle.com/bayarea/...f-13267862.php |
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I wouldn’t be surprised if the Transit Center takes until next year to reopen given the seriousness of the situation.
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Let's hope he's right because, since he's the guy hired to make the call, I assume the MTA will proceed to follow his recommendations. |
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Such a downer. Just stop and become positive about things.
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They were testing the gondola in the afternoon today.
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I’m not a downer. Just calling it as I see it.
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Some good news, several new retail stores are leasing space on the ground floor. Charleys, Tycoon Kitchen, and Foundation Cafe. That brings it to a total of 12 spaces out of 35 leased, across 9 tenants, with 47% of total retail square footage accounted for.
Additionally, the spaces that have been leased already are still being built out even during the temporary closing of the terminal. More info: https://www.bizjournals.com/sanfranc...g-closure.html |
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Now they are saying the building might not be open again until next summer.
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I too recall reading--but I can't recall where--that the reopening might not happen until the "second quarter" of 2019. That could be as late as June. But this piece from Curbed makes even that seem optomistic. If they don't have the results of the "in-depth analysis" until February and if they then have to order materials and schedule workers to do the repair, the lead time for which is unknown (and knowing as we all do how long things can take in this town), I'd cross my fingers even for June. The good news: No new cracks. |
New info, and looks like they have a fix ready that does not involve too much jostling:
According to the team, the probable cause of the fractures appears to be “the formation of cracks in the girder weld access [holes]” that were cut prior to the beams being placed into service. More specifically for the engineers in the room: 1. Initially, shallow (micro) surface cracks developed during thermal cutting of the weld access holes in the highly hardened and brittle martensitic surface layer [of the beams]. 2. Thereafter, larger pop-in cracks formed in two of the four flanges, potentially during butt welding of the flange plates. 3. Black, tenacious, high temperature oxide was present on both the shallow surface cracks and the larger pop-in cracks, confirming that both crack types formed at elevated temperatures. 4. The fracture origins were located in the mid-thickness of the flange where low fracture toughness, as confirmed by CVN [(Charpy V-Notch)] toughness testing, provided little resistance to rapid, low-energy, brittle fracture. 5. CVN testing was performed on all flange samples at the top, ¼ depth, mid- thickness, ¾ depth, and bottom. ¼ depth CVN results were found to be consistent with the project specification and girder plate mill certifications. 6. Rapid, low-energy fracture of the flanges occurred as the girder was subjected to service loading on top of the normal residual stresses due to welded fabrication. While further material testing and stress analyses are underway, and will be considered in the final root cause assessment due next month, it appears that the cracked flanges, which have maintained “sufficient capacity to support the building dead loads and occupancy loads,” can be fixed in place. As proposed by Thornton Tomasetti, the existing surface around the compromised flanges could be ground to a smooth surface, after which bolted cover plates would be installed above and below, restoring the beams to their original design capacity. http://www.socketsite.com/wp-content...Center-Fix.jpg http://www.socketsite.com/archives/2...dentified.html |
^^This more or less confirms what was hypothesized in my post #3304 above but what I haven't heard explained and don't understand is that if it was actually necessary to cut "welding access holes" in the beams, why such holes weren't "prefabricated" into the beams or at least factored into the original engineering and design. It still seems like somebody goofed--either the contractor by cutting holes they shouldn't have cut or the engineers by not taking the need to cut holes into consideration.
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I don't see this as a major problem. If, indeed, Caltrain needs to run more trains into the city than the capacity of the Transit Center, it can terminate and originate some trains at 4th & Townsend. Mission Bay is growing dramatically enough that many passengers may prefer to board or disembark there because they may live or work there. |
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^ Utterly ridiculous, and shows that Caltrain still doesn't "get" how regional rail is supposed to work.
Even if you assume ten minutes to turn a train (which is generous, and includes delays from interlockings and such) that's still 6 trains per hour per track, or 36 trains per hour total. More than double the 16 trains per hour that Caltrain says is impossible. Hell, Tokyo can do 26 trains per hour on a single set of two tracks on the Chuo Line. SF ain't Tokyo, but there's gotta be a way to achieve one fifth of that performance... |
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