The next dramatic addition to the Dallas skyline is taking shape on the banks of the Trinity River and also in Tampa, Florida. The twin arches of the new Margaret McDermott Bridge will carry hike and bike trails alongside Interstate 30.

The $113 million project was designed by Spanish architect Santiago Calatrava, who also designed the nearby Margaret Hunt Hill Bridge.

The scale of the arches is enormous. They’ll soar 328-feet-high with a length of 1,311 feet. That's longer than four football fields.

The Making of the Margaret McDermott Bridge

"It's definitely going to be another icon for the City of Dallas," said Duane Milligan, who oversees the project for the Texas Department of Transportation.

The two arches and their bridge decks are being fabricated by Tampa Steel Erecting in Florida. It's the same company that built Spaceship Earth, the giant geodesic sphere at the center of Disney's EPCOT theme park.

Company president Bob Clark says the Margaret McDermott Bridge is just as challenging. "It is probably as difficult as they would come," Clark said.

The steel arches are being fabricated in 78 sections, some of which are up to 60-feet-long. Because of the fluid design, no two pieces are identical. And they must join together perfectly.

Missing Attachment The first vehicles, motorcycles and a Vespa, rolled eastbound toward downtown Dallas at around 1 o’clock Thursday afternoon. The bridge will open in stages.

"Some of the tolerances are to within an eighth of an inch, some to a sixteenth of an inch," said Jeff Ames of Tampa Steel Erecting.

Before they leave Tampa, the sections are connected, then unconnected, just to make sure there are no surprises in Dallas.

The finishing touch is a gleaming coat of white paint formulated to last years in the searing Texas sun.

In a matter of weeks, the first sections will begin their 1,100-mile road trip to Dallas on flatbed trucks. "We don't want any bugs hitting them. No scratches," said Ames.

Once the pieces are in Dallas, cranes will lift them onto concrete abutments being poured inside the river levees.

The supports have a sculptural 'V' appearance. The arches will then rise piece by piece.

Missing Attachment It took awhile but the lights on the Margaret Hunt Hill signature bridge in Dallas came on Tuesday evening.

The first one, on the south side of I-30, should start going up by January.

The Margaret McDermott Bridge is scheduled to be finished in the spring of 2017.