FORT WORTH (CBS 11 NEWS) – Fort Worth residents got their first peek at the new Seventh Street Bridge’s construction and many liked the long arch with cables criss-crossing through its center. But engineers from all over are admiring the bridge for another reason: how its built.

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“It’s the only one designed like it in the world,” said John Carlson, District Manager for Sundt, the contractor hired to build the bridge. “It’s the only one like it, and it’s never been done before.”

The first of twelve, massive arches inched its way onto the bridge around 10 a.m. Friday. We’ve sped the video up, but it took nearly two and a half hours to roll the arch down the bridge, hook it up to the cranes and lift it.

The 300-ton piece is more than half a football field long.

The arches ride on self-propelled dollies with 240 wheels run by remote control.

What makes this project unique is all these massive pieces were carefully designed in a 3-D computer model and built on the banks of the Trinity.

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The off-site construction means the bridge will only be closed for around 150 days instead of a full year.

Because all those pieces of the puzzle go into the arches, sometimes they don’t quite fit,” Carlson. “And if we had not done that ahead of time, we would have come out here and start to build those arches and have had all types of conflicts and redesigns. But we were able to work out all those problems up front before we built the arches.”

There will eventually be six arches on either side of the bridge allowing four lanes of traffic, a center lane for a future street car and wider bike and walking lanes.

“It will be an aesthetically stunning bridge,” Val Lopez, TXDoT spokesman said. “The arches will also separate main lane traffic from pedestrian traffic. It will be a safer bridge for both motorists and pedestrians.”

“That’s really going to be nice for walking and bike riding over there,” said Mark Renfrow who lives downtown. “It wasn’t fun walking across that bridge but especially on a bicycle!”

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