Miami pedestrian bridge collapse

[California]

My own theories - no validation so far - are:

1) Project management. A colleague once got away with titling her internal audit report on project cost control as: 'We can find no focus of authority and responsibility.' *

2) Not an engineer but my instinct as a amateur is the bridge was designed to be carried into place by lifting it at each end. With a panel between the truck and the bridge to spread stress. Instead the North end was lifted with the weight bearing on a narrow line 20 (?) ft in from the end, so that the end was cantilevered over that narrow lift point - overstressing that line (which is where the bridge first broke) and possibly stretching a tensioning rod. Additionally the chart lists no rods for the last chord. That has to be an error in that (early) version of the drawing or else a gross error when moving the bridge, to support the bridge in a way that stretched an unreinforced chord.

 

[MossRoad]

Yes. saw that and agree with U.

Another thing that struck me is that there were 'cross walks' a mere 100 ft away which suggests 'pork barreling' (think is right term).

Did one get injured jay walking illegally?
Or walking while texting?
Are those students so lazy not to walk 100 ft more to cross safely?

My daughter went to grad school at Pitt. There are several other universities in the same area. They are in a city setting, and crossing the streets are downright dangerous. Keeping pedestrians out of traffic is a worthy goal, for both the peds and the automobile drivers.

 

[MossRoad]

My own theories - no validation so far - are:

1) Project management. A colleague once got away with titling her internal audit report on project cost control as: 'We can find no focus of authority and responsibility.' *

2) Not an engineer but my instinct as a amateur is the bridge was designed to be carried into place by lifting it at each end. With a panel between the truck and the bridge to spread stress. Instead the North end was lifted with the weight bearing on a narrow line 20 (?) ft in from the end, so that the end was cantilevered over that narrow lift point - overstressing that line (which is where the bridge first broke) and possibly stretching a tensioning rod. Additionally the chart lists no rods for the last chord. That has to be an error in that (early) version of the drawing or else a gross error when moving the bridge, to support the bridge in a way that stretched an unreinforced chord.

I tend to agree with your assessment. I saw some pictures of how it was supposed to be moved and then how it was actually moved.... they didn't match. So there you have it. It was lifted from a point not meant for lifting, causing unexpected stress/stretch in the tensioning system and/or concrete, weakening it.

 

[MossRoad]

"There are 10 kinds of people in the world...those who understand binary and those that don't"

From an old programming class...

 

[California]

A footnote I was drafting for my post above. After seeing Moss's cartoon I'll put it here instead:

*(footnote from above)
State DOT here. Long ago. Internal Audits branch. My colleague was sent out to analyze why the onsite project managers at construction field sites were screaming that they had lost all control over project costs because of transition from hand-kept cost records at the jobsite that they were responsible for, to primitive computerized reporting - where they filled out HQ-designed paper forms and mailed them in to be keypunched into cards (not necessarily timely), never to see their numbers added up before a printout was mailed back to them next month.

She wrote up her Audit Report and it was issued under the title: 'We Can Find No Focus of Authority and Responsibility.'

 

[PILOON]

In Toronto, Canada, at a crosswalk you raise your arm, (hand) and all traffic comes to a stop as that indicates you intend to cross.
Fines are very strict and that system seems to work.

 

[Jstpssng]

In Toronto, Canada, at a crosswalk you raise your arm, (hand) and all traffic comes to a stop as that indicates you intend to cross.
Fines are very strict and that system seems to work.

I like that. Oftentimes here it's hard to tell if someone is trying to use the crosswalk or waiting for the bus. (or just standing there.)

 

[buckeyefarmer]

Yes. saw that and agree with U.

Another thing that struck me is that there were 'cross walks' a mere 100 ft away which suggests 'pork barreling' (think is right term).

Did one get injured jay walking illegally?
Or walking while texting?
Are those students so lazy not to walk 100 ft more to cross safely?

Its lots of students crossing a busy road. Unfortunately they went for bling instead of function.

 

[bcp]

San Diego teen’s death led to construction of Florida bridge: report | fox5sandiego.com

MIAMI – The pedestrian bridge that collapsed near Florida International University killing six people was built to improve safety after an 18-year-old girl from San Diego died crossing the road a year earlier, officials said.

Florida International University freshman Alexis Davis was hit and killed by a motorist while crossing an eight-lane highway at Southwest 8th Street in August, the Miami Herald reported.

The bridge was supposed to enhance safety -- letting walkers and cyclists cross the busy street with less worry.

 

[MossRoad]

8 lane highway + college students = problems.