Two bridges in Minnesota were built using the Accelerated Bridge Construction (ABC) technique used for the under-construction pedestrian bridge in Miami, which collapsed on Thursday.
This relatively recent advance in bridge building sees the span of the bridge constructed separately, rather than being built-up directly over the road. This minimizes road closures and improves safety for construction workers.
Unlike in Florida, construction of the two Minnesota bridges built this way went off without a hitch, and now safely span I-35E in St. Paul.
Those are the Larpenteur Ave. and Maryland Ave. bridges, which the Minnesota Department of Transportation told GoMN were built several years ago using ABC.
"By using these methods, we were able to do construction in a safer environment and affect traffic for much less time," spokesman Kevin Gutknecht said.
The Florida bridge had been rolled into place last weekend, with workers continuing construction on it this week until it collapsed on Thursday, killing six people so far.
There's no need to worry about the two St. Paul bridges, MnDOT says, as both "are in good condition and have served the public well."
"With Maryland Ave., the span was constructed off to the side of the road and then picked up by transporters that moved it into place," Gutknecht added. The Larpenteur Ave. bridge was built off to the side next to the bridge location, and then slid into place."
The Larpenteur bridge saw hydraulic jacks used to slide the span into place.
Why I-35W bridge is safe
The Florida disaster also brought the 2007 I-35W collapse back into the news on Friday, after it emerged that the company that designed the Miami bridge, FIGG Engineering, also designed the replacement bridge for I-35W.
Again though, there are no worries about the safety of the 35W replacement, with MnDOT saying it's "in good condition" and has presented no problems since it opened in 2008.
The way it's actually designed mitigates the impact to the rest of the structure should a single section fail.
"The 35W bridge is a concrete box girder bridge, that is actually five bridges," MnDOT said. "Two bridges cross the river. Two more cross a city street on the north side of the bridge. And one bridge carries the ramp to University Ave.
"It is a redundant structure, which means that if some portion of the bridge fails, the structure will transfer weight to other parts of the bridge."