Designer calls new bridge simple, elegant, safe and smart

The collapse of the Interstate 35W bridge ripped a gaping hole in our collective psyche, but it also left a huge gap in our highway system. We now have our first glimpse of what may fill that void, at least physically.

FIGG Bridge Engineers Monday unveiled its vision of the 35W replacement bridge, a 504-foot span lifted 70 feet above the Mississippi River. The plans were made public for the first time hours after MnDOT officially awarded the $234 million contract to a partnership of Flatiron Construction of Colorado and Manson Construction of Seattle.

"Our major statement is that we will build the best and the safest bridge for all Minnesotans," project manager Peter Sanderson told reporters at the State Capitol.

The president of the FIGG design group, Linda Figg added,"First and foremost it?s about creating a bridge with high redundancy, high safety, long-term quality and low maintenance."

Figg called the design concept safe, simple, elegant and smart, an allusion to the state-of-the-art pavement sensors and other high tech monitors that will be built into the deck.

"It is a sculptural bridge where the form and the function work with proportion and elegance to create a model for other bridges in America."

The bridge will feature an array of lighting accents to make it pop visually at night. It will also allow extra room and strength for adding mass transit and a pedestrian bridge in the future.

A ceremonial groundbreaking is on tap for next Monday, with actual construction slated to begin as soon as early November. The goal, according to Sanderson, is to have traffic cross the bridge by Christmas Eve of 2008.

Flatiron-Manson's winning bid was $60 million higher than the lowest bid, but that proposal scored highest on technical merit. Designers say the concrete design, though more expensive, will be easier to maintain and blend better with the existing riverfront in downtown Minneapolis.

"It's an opportunity to sculpt the shape so it would fit in context with the site, be in harmony with the other beautiful architecture that exists there already," Figg remarked.

Peter Sanderson said the concrete box girders that will run the length of the bridge will give it exceptional strength and durability.

"It's a long lasting material. All of the components were made here. It will last more than 100 years."

The bridge engineering jargon of "fracture critical" and "redundancy" have also entered the vocabulary in the wake of the collapse, as the public learns more about how bridges are rated for design safety.

The 1967 steel bridge that fell was considered "fracture critical" because a failure in one key section could, and may have, brought down the entire structure. The new bridge, by comparison, will have built-in redundancy according to Sanderson.

"It?s a low maintenance product, and it?s a redundant design with no fracture critical members."

The hastily called Capitol news conference came just hours after the Minnesota Department of Administration formally rejected protests filed by two of the losing bidders. Those companies, CS McCrossan and Ames-Lunda, can still challenge the process in court.

In their protest petitions they contended that MnDOT threw them off track by suggesting that low cost and speed were the state's main objectives. The state gave bidders the option of submitting either concrete or steel, but since steel is less expensive the losing bidders went that direction.

The plans will be available for viewing at the State Capitol Tuesday, and are already posted on MnDOT's website. The agency also posted the competing plans by the losing bidders on its site Monday evening.

Figg also announced plans for a "Figg Bridge Design Charette" during the week of October 22nd. It will be a daylong session designed to seek input from the community, media and other governmental entities.

One key design decision that hasn't been finalized is whether to make the tops of the piers "T" shaped or more of a "Y" shape.

The collapse August 1st killed 13 people and injured more than 100 others. Figg said the new bridge will have observation decks "for recreation or for reflection."

She also said the structure should have plenty of opportunities for memorials, but "those will be local decisions."

By John Croman, KARE 11 News

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