2003 WRIGHT BROTHERS BOULEVARD
(Winner of a 2004 ACEC Award)
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The Eastern Iowa Airport in Cedar Rapids, Iowa, received approval from the Federal Aviation Administration (FAA) to extend Runway13/31.
Design for both phases began in May 2000. Phase II construction was done in the fall of 2001. Phase III construction was finalized in October 2002.
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Extension of the runway required the relocation of over two miles of rural and urban roadways to accommodate the runway extension as well as a planned taxiway bridge over the road. Ament was selected as the design engineer for the major roadway project that modified Wright Brothers Boulevard to meet the client's present and future needs.
Ament, Inc. created the conceptual design for Phases II and III of the project following another firm's Phase I work. The firm communicated with the team of the Eastern Iowa Airport, the City of Cedar Rapids, Federal Aviation Administration (FAA) commissioners and the Iowa Department of Transportation (DOT).
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Ament planned phased construction to minimize the impact on traffic flow to keep the main roads open to the airport and arterial roads open to the north, toward the city.
Temporary roads were designed and constructed to link Edgewood Road to Wright Brothers Boulevard. |
The existing road had to be relocated one-quarter mile north of its existing position and lowered by approximately 35 feet in order to pass under the planned bridge. Lowering a road this far below existing grade is uncommon in Iowa.
The relocation of the road below grade also required special attention to drainage requirements. Because of the depth of the excavation, Ament investigated several alternatives to remove storm runoff from the hole that was created by going under the taxiway bridge.
In the final design, Ament, Inc. decided to maintain positive drainage to the lowest point along the roadway corridor. From this low point, a minimum grade of 0.5% was maintained to a point intercepting the grade required to get clear the future taxiway bridge. This concept allows water to drain naturally and avoids the cost of constructing culverts/storm sewers, while increasing the volume of earth work. |
The project required approximately 700,000 cubic yards of earth work. The fill that was generated was moved to the nearby airport runway expansion project.
Staging for Edgewood Road was complicated by the 35-foot elevation difference between the new Wright Brothers Boulevard and the existing Edgewood Road. |
The successful low bidder of Phase II identified clay soils deep in the excavation that in their opinion were superior materials for constructing the roadway. As part of a value engineering process, they recommended that these soils be used to construct the pavement sub-base in lieu of the granular sub-base included in as-bid plans.
After meeting with the geotechnical consultant, their proposal was accepted and plans were changed to use the on-site clay. The change resulted in savings of approximately $100,000 while conserving the granular sub-base, which is a nonrenewable resource.
Connection with Phase I and the reconstruction of Edgewood Road both required complicated staging plans. The connection with Phase I was complicated by the construction of a temporary roadway between the end of Phase I and old Wright Brothers Boulevard and the need to maintain the primary access to the airport. |
Technical Value to the Engineering Profession
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The majority of the $1.741 million cost savings experienced on the project and related to the efficiencies of scale in this portion of the project.
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Designing Wright Brothers Boulevard to pass under a future taxiway bridge required an unusual amount of earth work. Ament investigated several possible vertical profiles that considered the earth work and storm sewer costs of each alternative. The chosen alternative minimized the storm sewer costs while increasing earthwork. Because of the large drainage areas (requiring large storm sewers) and the desire to minimize the problems created by a sump condition, the chosen alternative was the most economical. In addition, the good quality of the generated fill made it possible to move that dirt to the airport's other construction projects, resulting in further savings.
The Phase II contractor unearthed and identified clay soils that they believed to be superior materials for constructing the roadbed. As part of a value engineering process, the contractor proposed that the clay be used for sub-base construction in lieu of the granular sub-base called for in the project plans. Ament and the geotechnical contractor reviewed the contractor's proposal and accepted the change into the construction plans.
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