By DAVID ELBERT
REGISTER BUSINESS COLUMNIST

You probably don't think of a freeway as either a park or work of art, but $20 million of the $429 million cost of rebuilding Interstate Highway 235 through the Des Moines area is going toward design features to make the road visually more attractive.

"We have yet to understand what it will mean to have a 14-mile linear park" running through the city, said Des Moines architect William Dikis, whose firm, RDG Planning & Designing is a consultant on the freeway project.

That's how Dikis sees the freeway, as an elongated, L-shaped park, and he thinks that by the time the project is finished in 2007, others will agree.

A good chunk of the design money will go toward landscaping, which isn't obvious yet because much of the actual planting will occur in the final phases. But the five-year project is far enough along that design changes to the road are becoming visible.

New bridges are the most obvious change. The new bridges across the freeway are longer, because the freeway is wider, but they also have fewer support piers, which gives them a cleaner, more open look.

"It really opens up your views," said architect Kimball Olson of the Iowa Department of Transportation. "You don't have these forests of columns that were underneath before, and really muddy up a bridge's appearance."

Downtown, the original bridges built in the mid-1960s created a tunnel-like effect for drivers on the freeway.

Now, the new structures "are like opening a window shade. Light is coming in that wasn't there before," said Jesse Lewis, a landscape architect in the RDG firm.

To build the bridges, a new style pier was created by state engineers, said Olson. The piers use a poured-concrete delta shape - an upside-down triangle - for support. The design is flexible, so that it takes on slightly different shapes in different locations, he said.

Each pier is V-shaped, and two piers together look like a W, which has prompted Iowa DOT Director Mark Wandro to claim them as his personal monogram.

Seriously, Wandro said, this freeway will be far classier than the one built 40 years ago. The I-235 freeway of the 1960s was driven entirely by cost. A lack of planning was apparent from the day it opened and drivers discovered they could not stay in a single lane all the way through town.

When the rebuild is completed, drivers can drive all 14 miles without changing lanes and more.

"We've become a little softer, a little more enlightened on what we can do to appeal to communities rather than just be functional," Wandro said. "We consciously built into this project an additional 5 percent to enhance the visual and aesthetic components."

"We could have saved money and had a more traditional highway," Wandro said.

"This isn't going to be unique to Des Moines," he added. Freeways redesigns are being planned for Council Bluffs, the Quad Cities and Sioux City with similar amenities.

Another design aspect of the new I-235 will be the way bridges over the freeway tie together, Olson said.

Bridges outside the downtown area are supported by long spans of pre-cast concrete. Those spans will eventually be coated with a white sealant, which make the bridges stand out against the landscape, like the new Corporate Woods Drive bridge across Interstate 35 in Ankeny does now.

The Ankeny bridge, which was completed last fall, was a prototype for bridges in the I-235 project, as well as future bridge rebuilds on I-35 and I-80, Olson said.

Meanwhile, he said, downtown bridges are being built atop Core-ten steel girders that are similar in appearance to the rusty looking exterior of the Ruan Building in downtown Des Moines.

The more expensive steel is being used for the downtown bridges, he said, for both design and structural reasons. The downtown bridges require more strength, which the steel has, but it also helps to break up the look of the freeway for drivers, Olson said.

The steel is low-maintenance, because it does not need to be painted, "but I like the stuff because it has a natural beauty," and it adds to a feeling of strength in the downtown area.

"It breaks up the lines of a bridge. It makes the bridge appear longer because you've got a deep, dark color on the beam, than when you have white or light colors above," Olson said.

When the freeway is completed, Dikis predicted, it will be seen by engineers and architects nationally as something special, a demonstration project.

Wandro said the approach wasn't done to get national recognition. "If it's viewed nationally, as something that could be done elsewhere, all the better."

"The bridges are a statement for the community," said Olson, "but they are also a symbol of state pride that is going to disseminate from Des Moines and move to other communities" as other projects come on line and are completed.