Minnesota bridge opens a year after deadly collapse

Honking their horns and stirring up faint clouds of post-construction dust, hundreds of drivers helped open the new Interstate 35W bridge this morning just a few minutes after 5 a.m.

The two processions -- one from the south end of the bridge, one from the north -- were led by representatives of agencies that were the first responders when the old bridge collapsed last year. They were followed by Minnesota Department of Transportation maintenance trucks with sturdy, wide bumpers that kept drivers in line.

Vehicles coming from the south were the first to make it across the 10-lane bridge, which was bathed in the bluish glow of its LED overhead lights.

Drivers and passengers waved at each other through windows and sunroofs as they cheered and snapped photos with cell phones and digital cameras.

"They're going to be all over the map. There are some people who are probably looking forward to crossing the bridge and there are some who you probably couldn't pay to cross the bridge," said Margaret McAbee, director of Survivor Resources, which has been holding weekly meetings for bridge-collapse survivors and families.

"Trauma doesn't have much logic involved with it. ... It's probably the strongest bridge in America ... But for the people who are fearful, again, logic doesn't fit into the picture."

The purpose of the "smart bridge" technology isn't to warn of another impending disaster; it's to detect small problems before they become big ones, said Alan Phipps, design manager for the project with Figg Engineering Group Inc. of Tallahassee, Fla.

"What these sensors are for, it's like going to your doctor for your health checkup," Phipps said. "It's to ensure you're maintained in top shape so you never get close to having a serious problem."

The sensors will measure how the bridge handles loads and vibrations and how it expands and contracts as Minnesota alternates between frigid winters and steamy summers, as well as watch for corrosion from road salt.

A system of sensors and cameras will feed data on traffic flow — including speeds, accidents, stalls and other disruptions — to a management center. Other sensors will activate an anti-icing system when necessary, and security sensors are meant to detect intruders in unauthorized areas, such as the hollow concrete box girders.

The data will feed into computers in a control room near the bridge, Phipps said. From there, engineers at the Minnesota Department of Transportation and researchers at the University of Minnesota can download it for analysis.

Catherine French, a civil engineering professor at the University of Minnesota, has worked with the developers of the system and will be among the researchers analyzing the data. The number of sensors on the bridge, and the fact that they were installed from the start, make this project stand out, she said.

"It is kind of on the cutting edge," French said.

The main value will be the insight the system provides for building future bridges. Engineers will be able to compare the bridge's behavior to models they've developed, she said.