Analysis of collapse dynamics: The Mirror Cinema

<prev< Album year 2007, including historic postcards

>next> La dinamica del crollo - Videocamere aggregate (24 Agosto)

Analysis of collapse dynamics: The Mirror Cinema

On August 20, "Guardia di Finanza" authorities released a security camera video showing a very restricted view of the bridge collapse. However, a blurry image reflecting on the wet roof of a building reveals more, especially relating to the important first instants of the collapse.
This page is bilingual.

What do you think? Have you discovered more hints? Please comment...

1.) Video frame analysis: Camera view explained

The image below shows the camera view, the following text describes it:

Only part of pylon 9 is visible in the upper right corner of the image
The bridge deck is located approximately 45 meters above ground. Its orientation is shown by the black arrows
The red coloured area mirrors a shape of the bridge deck, before collapse, and morphs its shape during collapse. This analysis decodes and explains those mirrored shapes and its different phases during collapse.
It is drawn on a building roof. While the bridge collapses, it acts as a canvas
Polcevera" is the riverbed. One can see the industrial buildings on the opposite riverside
When viewing the single images, please click the bigger view again to get a less compressed, better quality version.

f01-cut.png (425149 bytes)

2.) Video frame analysis: Original Video

Follow the >link to the original video< by the 'Guardia di Finanza' on Youtube by "RepTV" . Watch it first to get a first impression of the dynamics.

3.) Video frame analysis: Annotated animated GIF

Here I took relevant frames from the original video, and added explanatory lines and annotations. The animation repeats itself and can not be stopped, but each single frame can be found in the photo collection further down this page. Scroll down to find translations IT to EN of the annotations added.
(The GIF may take a while to load, the timeline is shown, but the Youtube video control buttons of course do not work)

Genova polcevera bridge collapse analysis animation

( Should the animated GIF not display, please follow this >link< )

4.) Video stills analysis

* Click on a thumbnail an then the < and > arrows to step through frame for frame
* Or - Click the grey square above to toggle "all images on one page" - mode.

Notice: Click on the thumbnail and then on the larger image again to view it at a (slightly) higher quality, full screen.

To be precise: The the still images are taken from a video released by the "Guardia di Finanza" (Italian Tax Police), to which I am not affiliated. I have added colored lines and text.

01
02 - Right before collapse begins. The red outline delimits the mirrored bridge deck
03 Road deck of pylon 9 detaches. Deck of pylon 8 remains in place. Gerber element in-between could be possibly visible (pink outline)
$Analysis of collapse dynamics: The Mirror Cinema : 04 For a fraction of decond, a vehicle's headlight becomes visible (might be also sparc from electric cables). The bridge deck continues to tilt$

04 For a fraction of decond, a vehicle's headlight becomes visible (might be also sparc from electric cables). The bridge deck continues to tilt
05 The first debris become visible. In the image, their longitudinal shape is outlined by green lines.
06
07 The westernmost bridge deck becomes visible (light blue outline). Deducting from other images it is tilted 90° to its left and will later be found in the river bed, like a spade in the soil
09 The western end of the cantilever element falls further. It is only half of the cantilever, it has somehow broken apart from its other half attingent with pylon 9
10 The cantilever "half" attingent to the pylon comes down (yellow outline), hiding the other half from the images before (blue outline).
11 The cantilever "half" attingent to the pylon contunes its fall (yellow outline), hiding the other half from the images before (blue outline).
12 while the cantilever "half" contunues to fall nearly vertically, the reflection on the wet roof changes its shape (bottom of image)
13a A horizontal crack appears in the lower base of the visible pylon leg. It will slightly tilt towards north. More debris falls on the left
14
15
16
17
18
19

Keyword translations Italian -- English

* tettoia edificio - roof of building
* rifessioe impalcato - mirror outline of bridge deck
* pilone 9 lato sud-ovest - south western edge of pylon 9
* impalcato pilone 8 - bridge deck part of pylon 8 (did not collapse)
* impalcato pilone 9 - bridge deck part of pylon 9 (did collapse)
* scintille rottura cavi elettrici - breaking/short circuiting electric cables emitting sparks
* caduta primi detriti - first debris falling (over river Polcevera)
* impalcato estremità ovest "spada nel Polcevers" - most western bridge deck (of pylon 9, "sword in Polcevera" (because the way it impacted)
* impalcato ovest estremità lato pilone 9 - western bridge deck close to pylon 9
* Antenna o strallo - Pylon antenna or cable stray

5. Suggested next steps / prossime analisi consigliate

It should be possible to precisely reconstruct the spatial dynamics of the collapse with the aid of 3D CAD tools. To do so, it would be necessary to exactly measure fixed points coordinates in reality and on the mirrored wet roof, like the corner of the part of the bridge that remains intact and perfectly reflects its shape in the wet root. Knowing the camera coordinates, its focal length (and distortion), it should be possible to translate the mirrored shapes back to their physical positions i

6. Simplified 3D-Anasysis

One may make use of the limited yet powerful 3D views of Google Earth to simulate the surveillance camera view. The aim is identifying from which bridge parts debris fall into the camera view, and therefore contribute to a better initial understanding of the collapse dynamics.

Note: To view an image in adequate quality, please click it, until it appears in full-screen mode!

Comment on this page...