Designer of fallen Florida pedestrian span was initially on Bob Kerrey bridge project

Omaha World Herald ^ | April 2, 2018 | Andrew J. Nelson

[jim_trent]

The same company that designed a failed pedestrian bridge in Florida was the initial designer of what would become the Bob Kerrey Pedestrian Bridge.

Florida-based Figg Bridge Engineers had the original contract to design the pedestrian bridge that spans the Missouri River between Omaha and Council Bluffs.

Figg was behind the design of the pedestrian bridge at Florida International University in the Miami area that collapsed March 15.

But Figg ultimately did not provide the design of the Omaha bridge. The reason wasn’t safety. It was cost.

Bids to construct the Figg-designed bridge came in at twice the cost that the cities were prepared to pay.

The original Figg design went out for bids in early 2004. The bridge was expected to cost $22.6 million, but bids ranged from $44.9 million to more than $50 million.

The City of Omaha worked with Figg for about four months to make the bridge design less expensive.

“All those alternatives turned out not to be plausible, so in the end we terminated our relationship with them,” said Larry Foster, then the city’s administrator of parks, recreation and public property. He was project manager for the bridge.

After the city scrapped Figg, it hired HNTB of Kansas City to design the S-shaped bridge.

The HNTB version wasn’t as wide and used simpler construction methods, helping make it less pricey. APAC Kansas built it.

“It’s very similar, just less expensive,” said Foster, now the director of parks and recreation in Council Bluffs.

The bridge, which opened in September 2008, is walked by a foreman at least once per week to look for problems, said Brook Bench, Omaha’s parks and recreation director.

This summer, it is due for a major top-to-bottom inspection, Bench said.

“Every five years we do a major inspection, which is the cables, under the water, top of the towers, the whole ball of wax. We did (the first) one five years ago. It is due for another major inspection,” he said. “There actually will be divers in the water.”

[jim_trent]

My understanding from the time was that the bridge from Figg was unbuildable. Both the horizontal and vertical structural members were one piece cast concrete. That is why the cost came in twice what they estimated.

The redesign by a different company looked very much the same, but it was simple to build. In addition to being simple to build, it would have been easy to check the stresses. HNTB completely separated the horizontal and vertical structural members and most of them are metal (except for the abutments and piers).

[neverevergiveup]

For those of us who are not engineers, does this essentially mean that the same company had put forth a flawed design previously?

[AnalogReigns]

I’ll bet it wasn’t the design of the FL bridge that was bad....rather the construction itself. Sub-par concrete—in an industry often run by the mob—isn’t all that uncommon. Or who knows—could be many other things. Cost-saving deviations from an original design, can be deadly.

[southernnorthcarolina]

But did he design the Teddy Kennedy Bridge?

[jim_trent]

It is impossible to tell at this time if the Omaha design was flawed. However, it was designed in the same way (as far as I can tell) as the flawed design was.

The design that was built used steel segments that were erected from each pier and immediately attached to the supporting wires. After the metal framework was completed, the flooring was cast with stay-in-place forms. The concrete carries very little load (the people walking on it), while the steel carries the vertical and horizontal loads. Very little work needed to be done in the water or from the water.

The original design by Figg had heavy concrete vertical and horizontal structural members. It would have take at LOT of work in (or from) the water with elaborate forms to hold the concrete while it cured. That is much more expensive and also more likely for a mistake being made while the concrete was curing.

My suspicion is that the Omaha bridge was structurally flawed, too. We missed out on making national news because of cost, however.

[az_gila]

For those of us who are not engineers, does this essentially mean that the same company had put forth a flawed design previously?

---

Not quite “flawed”.

Perhaps a better description may be that the original design was over-complex and designed in a way that was hard to calculate stresses and would have been built in a way that was hard to inspect.

Just my engineering guess from the previous description.