Running a four-lane highway under a railroad overpass and then jumping it over a river, a recreation trail, and another railroad via a 1,100-foot bridge was one of the most complex and costly projects in Iowa's history. Photo: Ron Nicolls

By Victoria K. Sicaras


CLIENT:8Sioux City (Iowa) Engineering Department/Public Works
AEC FIRM:8HR Green Inc.
COST: $35 million
COMPLETED: January 2010

Getting from one end of Sioux City, Iowa, to the other has never been easier now that two at-grade railroad crossings are gone forever.

Since the 1970s, the Outer Drive has dead-ended at a residential boulevard, leaving the northern and eastern halves unconnected. The lack of roadway infrastructure combined with heavily used at-grade rail crossings caused numerous traffic delays; drivers either had to wait for mile-long trains to cross intersections, or travel several miles to the nearest grade-separation crossing.

“This was a sorely needed project,” says Bill Moran, PE, vice president of HR Green Inc., the consulting firm that planned and designed a 1-mile extension that takes drivers directly to U.S. Highway 75, finally connecting the north and east sides of the city. “It completes the missing link that allows vehicle traffic to cross the Hoeven Valley and its several railroads unimpeded.”

Any improvement involving railway presents a special challenge. In this case, engineers wanted to run the new road extension under one railway and then over the Floyd River and a section of another railway. Negotiating with the three railroad companies that were affected pushed completion of the project, which began in 2002, three years past the initial 2007 estimate.

The goal was to provide a new river crossing and two grade-separated crossings, which had to occur within approximately 3,000 feet.

To do this, 7,000 feet of track — almost 1½ miles — on the north side of the project had to be relocated. Although owned by Canadian Central and Pacific (CCP) Railroad, another company — Union Pacific Railroad — is the primary operator on the track. Thus, rail relocation and new highway crossing agreements had to be negotiated with both companies.

On the south side, a new overpass allows the road to pass under the Burlington Northern Santa Fe Railroad. A temporary shoo-fly — the railroad equivalent of a road bypass — on a trestle kept trains running while the permanent railroad bridge was built. Because the road's low point is near the river levee system and didn't permit positive drainage, a stormwater pump station was built to prevent flooding.

To facilitate funding and competitive bidding, construction was divided into four phases and eight bid packages, one each for eight smaller projects.

Managers already had $6.4 million in Federal Highway Administration (FH-WA) demonstration project funds by the time the initial design phase began in January 2002. Breaking the overall project into smaller pieces ensured expenditure of these funds while managers requested — and received — $13.4 million more to design and award the next steps. Construction of the first project began in November 2003 and the final project — the Outer Drive Bridge— was completed in January 2010.

Ultimately, managers received $20 million in federal funds, $2.7 million in state grants, and financed the balance with tax increment financing and general obligation bonds.

Almost 30,000 vehicles have used the extension in its first year of operation. That traffic is drawing more businesses to the area: hundreds of acres of land ripe for commercial, industrial, and residential development.

Top AEC Firms