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Just having fun picking out the many flaws. It would also be interesting understanding how a "pre-engineered" structure doesn't match any of the standard models.

Thanks. It doesn't look like an installation problem but I'm still curious as to the procurement and design anomaly.

Can you source that article? Given the fundamental design differences, that would make sense. The typical Crescent designs are Pratt trusses so it's quite likely the failed structure is the state provided gangway. All the more reason to have outside investigators. I don't know if it's just...

From news article here

From the Minorcan video, the mainland dock appears to be of the same vintage as the island dock, i.e. they were both renovated as part of the same project. A significant difference though is that the pony truss on the mainland side is a Pratt design whereas the failed structure was a Howe...

By the same method, the truss section interval is 48".

Scaling off the 4" rub rail or 6" bottom chord, I get a height in the order of five feet. Also, the worker holding the top rail is barely taller than the height of the gangway. I also see some camber in the structure as it sits on the barge though it's difficult to measure. Unfortunately, the...

It's rather difficult to differentiate damage sustained during recovery from that of the collapse however I derived a cross eye 3D view from the above posted video link in case it helps to understand the current state of the structure. Note that the damage on either side does not occur at the...

Except that we can still see the diminutive cross span ribs so it's a combo toe kick / rub plate. For another dollar they could upsize it.

The road deck had not been removed from the center span. That was the primary imbalance with the digger being the final straw. The frame sticking up in the air is from the far end of the structure flipped over the support. It's not from underneath the center span. It's a truly bizarre...

The torn thin plate atop the hollow section may be an additional rub plate as it obviously has no structural purpose. It looks like a number of clean tears occurred at butt weld connections.

I think it buckled in keeping with bugbus' first scenario. splat

I think I see what happened now. The bridge deck was stripped off the far end of the structure leaving the skeleton frame work. This removed the counterbalance to the cantilevered center span. With the mini excavator on the center span, the centre span dropped, landing in the river intact...

Document referred to abovehttps://files.engineering.com/getfile.aspx?folder=e38dfcb1-eb49-4e3f-971a-ad31fffb8d52&file=CHD-3-HEAVY-DUTY-GANGWAY-60FTX3FT.pdf

From Wayback Machine - http://crescentdock.com/]crescentdock.com[/url] These screen grabs are from a promotional brochure (attached below). The failed structure differs somewhat in that the diagonals are inverted and the depth likely 48" or more. I suspect the landing truss section mirrors...

So we're good at 75 to 80 feet? That works for me. I was thinking 20 truss sections at four feet each would equal 80 feet as an outside estimate. Also, the gangway has to be longer than the span for tidal height variations.

That would be consistent with the gangway sloping down to the dock during low tide. The image only shows six of twenty truss sections.

Roughly, the span is 75 feet. Twenty sections of Howe truss (verticals in tension). The rail stock still looks inadequate. It only took 20 people to bring down this structure, only 1 per truss section. That's some bad math. Tug, no, it looks like another eclectic computer wiz design though...

The difference between the bridges in the photos and the failed gangway is the heft of the railing stock. The lightweight gangway railings do not even pretend to be structural (at the ends, the diagonal doesn't even align with a design node). Also, the gangway (servicing a ferry) is intended...

Aerial view on Bing Maps. Google is outdated. Low tide was 4:52 p.m. The incident occurred approximately 4 p.m. (Oct 19)