Structure inspection

There are radar like methods the scan structures like this.

Did it buckle in the middle or fall off the ledge at one end?

Overpasses like this usually rest in place and if the piers move apart it can slip off one end and after one end fall, the other follows.

Freez thaw cycling of trapped water can gradually make the piers move and cause this type of problem.

Was the piec that feel from thr road or from the edge of the pier? If from the egd of the pier it shows a huge force on a smaller and smaller area that would quickly tilr the pier and cause it to fall from the ledge.

An inspection might show this if the inspector knew where to look.

Search for "highway inspection" +radar

http://www.google.ca/search?hl=en&q=%22highway+inspection%22+%2Bradar&btnG=Google+Search&meta=

That sounds like the end shelf or sill broke off at one end allowing one end to slip down at one end and then the weight of the section would quickly force fail the 'nip' and the bridge would soon fail. This seems to be an inspectors fault, as he should have inspected the sills with care.

often bridge section like this have each end resting on a sill or shelf on the pier, held there by gravity and free to slide a little with thermal changes. The shelf must be made of the top grade of concrete and can also be steel covered. You have probably seen this type of construction all over the place. If the gap gets filled with compacted gravel then thermal change can gradually make one of the piers lean a little. The road bed contracts in the cold and gravel packs down. The next warming and the packed gravel halps force the piers aparts All things still look OK, but the bridge is getting close and closer to falling off one of the sills.

So the sills were too small, maintenance was bad and so was inspection.

Blame it on the unions wanting so much $$ for inspectors that they hade to economoze and the city w as also unable to get rid of bad inspectors due to union action.

Thanks Aurizon,

Doesn't make me feel any better about the rest of the structures over the highways but at least I have a better understanding of what probably happened. And hopefully, so does the gov'nt ! Maybe now they will enforce more thorough inspections.

for non destructive testing

there is accoustical, ultrasonic and radar

Sorry had to login

I have done this type of non destructive testing on bridge piers

(accoustical, ultrasonic, and radar) in Denver colorado, it is very revealing.

I will contact the Doctorate under which this was done to locate results and methodology. I will post it when I get the info

I think one of the main culprit in this particular bridge is concrete failure, the possibility of improper mixture was used, concrete design mix was not followed and the water cement ratio was not observe, maybe the first move for the inspector is to do is to check the soundness of the concrete.

They should have been sampling the concrete at time of pour and keeping those samples for tests then and at set later times.

From another photo in the papers it seemed to me that the piers diverged and one end fell off the sill. This indicates that they did not have an annual pier survey (which will spot pier drift)

In addition, the sills may have been too small?

UPDATE:

The investigation is finally finished. There is now a "blaming war" going on as to whose fault it was. Some say it was the engineers who didn't do their jobs properly and the engineers are blaming the crew for not following the design. After an extensive review, the Quebec government decided to take down 15 more "overpass" (bridges) as a precautionary measure. Insane.

Rick.