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new bridge erection technique

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Over the summer I noticed on I-4, the main corridor thru Central Florida, that they were replacing a small overpass bridge. No big deal. This is in an area I do not drive thru that often. Some weeks later I drove by and I see this large construction site taking shape a good 1/4 mile away from the bridge, off in the right of way. Couple of weeks later, they have erected several bulb-T type precast bridge girders and deck off on the right of way, on what appears to be scaffolding/cribbing jseveral feet off the ground, and this is like I said about 1/4 mile away from the piers/bents that are now constructed.
So now I am thoroughly confused. How do they plan on getting that bridge deck a 1/4 mile over to the piers, and why would they do it that way (seemed risky and expensive using cranes)? Couple of weeks go by and now the bridge deck is up on the piers.
This morning with my cup of coffee I am getting caught up on some engineering magazines (my personal nerd time), and there is an article in ASCE about THIS bridge (pg 38, ASCE, Aug 06). Turns out my confusion was not just due to my lack of bridge construction knowledge, but this was done for first time in the US on an interstate bridge overpass. They used self-propelled modular transporters from the Netherlands. These look like tractor trailer flat beds with a dozen axles that each can rotate, and they can be raised and lowered. They were used to remove the existing bridge spans in two nights per span (vs about 12 using traditional demo), and erect the new spans in about 3 days to erect (vs 20 nights of lane closures). I have seen these types of machines on the Discovery Channel or TLC when moving large steel tanks and other massive construction equipment.
Anyway, I am not even involved in bridge design or construction, just thought it was a neat idea. Seems much safer and better for traffic (my personal interest), not to mention a faster schedule. And suprisingly enough, with construction costs as high as they are, the whole extra operation only cost $564k, which included temporary foundations and driving surfaces for the modular trailers...
Andrew Kester, PE
ADK Structural Engineering, PLLC
Lake Mary, FL
N:Andrew Kester;PE
FN:Andrew Kester, PE