I-215 closed in Perris

[rschen7754]

http://www.latimes.com/local/lanow/la-me-ln-215-freeway-closed-bridge-collapse-20140715-story.html

Southbound reopened, but northbound is closed while they clean up the roadway, and will be for about 12 hours.

This sort of "accident while bridge falsework is constructed, thus delaying the completion of the project" seems to be happening a lot lately...

[roadfro]

I gotta wonder: Was the bridge clearance not adequately signed (including active detection/warning systems), or was the driver just ignorant to the warnings in place?

[rschen7754]

On the news they said a similar thing happened last year at the same interchange, just going the other direction.

[Indyroads]

This sort of "accident while bridge falsework is constructed, thus delaying the completion of the project" seems to be happening a lot lately...

This makes me wonder why CalTrans hasnt moved to a more efficient method for bridge construction rather than using falsework. Seems like it would be better for them to follow in the footsteps of Idaho or Indiana and use steel or concrete beams and only have to build the deck in place. Not sure how they would retrofit that for seismic strength but the falsework construction method seems to take a long time and restricts the roadways more than other methods.

[myosh_tino]

Seems like it would be better for them to follow in the footsteps of Idaho or Indiana and use steel or concrete beams and only have to build the deck in place. Not sure how they would retrofit that for seismic strength but the falsework construction method seems to take a long time and restricts the roadways more than other methods.

I think you hit the nail on the head with "seismic strength".

There are a few cases where Caltrans used pre-cast bridge sections when building an overpass but it's rare because of the added cost of transporting them and the fact that a full-freeway closure is needed during installation.

[roadfro]

This makes me wonder why CalTrans hasnt moved to a more efficient method for bridge construction rather than using falsework. Seems like it would be better for them to follow in the footsteps of Idaho or Indiana and use steel or concrete beams and only have to build the deck in place. Not sure how they would retrofit that for seismic strength but the falsework construction method seems to take a long time and restricts the roadways more than other methods.

It all comes down to cost of labor and materials at the time of design.

Falsework method is traditional reinforced concrete. It takes longer to erect the falsework and put rebar in place before the bridge pour. However, the bridge can typically be poured without closing the roadway below.

Steel girder construction can be much quicker to construct. However, steel girders can cost a lot to fabricate and ship to the construction site, especially with how much steel prices can fluctuate. The fabricated steel pieces have to be exact and formed to specifications, or else modifications have to be made--the structural integrity of the bridge depends on this (such an issue is the cause of all the new SF Bay Bridge scrutiny). Also, safety measures require that the roadway below be closed whenever girders are lifted into place.

Pre-cast concrete bridge sections is somewhat of a blend between the two. However, the cost of this makes this method much more impractical to use in many situations--I think this is more prevalent on flyover ramps and other cases where it would be extremely impractical to use falsework forms but the cost still clocks in under steel girder designs.

I think you hit the nail on the head with "seismic strength".

I don't think that seismic concerns would preclude using steel girder construction though. Nevada is the 3rd most seismically active state (behind California and Alaska), and there is an abundance of steel girder bridges around in both the north and south. Although I'm not 100% certain on this.