With traffic numbers expected to nearly double by 2030, the Iowa Department of Transportation is taking steps to improve the I-80 interstate system through Council Bluffs.
Routine maintenance projects have been completed since the interstate was constructed in the 1960s, but no significant changes have taken place since that time. A study of the interstate system in 1997 showed that the interstate does not meet current design standards, guidelines or operational criteria and cannot handle current traffic.
Currently, the interstate system in Council Bluffs typically carries 20,000 to 75,000 vehicles daily, with 11 to 25 percent of those vehicles being trucks. On some areas of I-80, more than twice the number of vehicles use the highway, compared with the amount of traffic that was originally estimated to use it. By 2030 traffic on I-80 between the I-29 interchanges is expected to increase to more than 120,000 vehicles a day. Currently, traffic on I-29 north and south of I-80 averages 20,000 vehicles each day, a number that is expected to at least double by 2030.
In 2002 the Iowa Department of Transportation (Iowa DOT) initiated the Council Bluffs Interstate System (CBIS) improvements project to address the issues raised by the 1997 Council Bluffs Interstate System Needs Study and develop solutions to improve the interstate system in the Council Bluffs metro area. Due to the magnitude of the improvements needed for the Council Bluffs interstate system, the project will be implemented in smaller manageable segments over time. Boundaries were established in Tier 1 to divide the system into five segments with logical ending points that could be designed and built independently of adjacent segments.
Work began in 2006 when the Iowa Department of Transportation constructed an interim project on the overlapping section of I-80/I-29 to add a third lane in the eastbound direction to ease some of the congestion that occurs when eastbound I-80 and southbound I-29 merge onto one roadway, according to the Iowa DOT.
Reconstruction of the 24th Street Bridge, a $7.5 million project, over Interstates 29 and Interstate 80 (I-29/I-80) took place in 2007 and 2008 to lengthen the bridge in preparation for full reconstruction of the I-29/I-80 overlap section. The longer bridge allows the I-29/I-80 lanes to pass underneath the bridge. The project included reconstruction of 24th Street from just south of 27th Avenue to the I-29/I-80 eastbound ramp intersection.
Precast bridge panels and post tensioning, which is a method of reinforcing concrete with high-strength steel bars, allowing longer clear spans, thinner slabs and fewer beams, were used on the 24th Street Bridge which, along with some scheduling changes, allowed this two-year project to be completed in one year, explains John Carns, project coordinator of the Iowa Department of Transportation District 4 office in Atlantic, Iowa. “The purpose was to explore new construction techniques to expedite a project while causing less interference with traffic.”
Now 24th Street includes two through lanes in each direction and allows for left-turn lanes at the interstate on-ramps
In August of 2010, four sculptures of artist Albert Paley, called Odyssey, were placed on the 24th Street Bridge, one on each corner. The sculptures were created with three metals, stainless steel, weathering steel and bronze plate. The $3 million cost of the art work was paid for by the Iowa West Foundation. The Iowa DOT engineers were part of the planning process for the sculptures, ensuring they were structurally sound and able to withstand the wind, ice and snow common with Iowa weather, according to information from the Iowa DOT.
Work on Segment 1 of the multi-year effort began in Omaha, Neb., in 2008, just east of the I-80/I-480 system interchange and continues east across the Missouri River to just west of the I-80/I-29 west system interchange in Council Bluffs, Iowa. This segment includes improvements to the 13th Street interchange (in Nebraska) and construction of a second $56 million bridge over the Missouri River on I-80 just north of the existing bridge.
The new I-80 bridge is just under 2,500 ft. (762 m) long and 84 ft. (25.6 m) wide. About 17,000 cu. yds. (12,997 cu m) of concrete were used to construct the new bridge and the piers. There are just two piers in the middle of the river, which provides the 425-ft. (129.5 m) span needed by the Coast Guard. The bridge deck sits between 70 and 80 ft. (21.3 to 24.3 m) above the water.
Sectional barges were transported to the project to transport materials and equipment to the middle of the river. Cranes used on the project include a 225-ton (204 t) crane, three 65-ton (59 t) cranes, two 100-ton (90.7 t) cranes, a 70-ton (63.5) crane and a 50-ton (45.3 t) crane, all of which were sitting on sectional barges in the middle of the river during the construction process.
In October of 2010, crews completed the I-80 Bridge on the Iowa side of the bridge. Traffic was moved onto the new bridge in October so work could begin on the old bridge. The old I-80 Bridge will be used in addition to the new bridge. The old bridge will undergo rehabilitation of removing the center median to provide additional space for one more lane. The old bridge carried four lanes of traffic; once it is completed it will carry five lanes of traffic, as will the new bridge making it less congested for the 130,000 vehicles that travel through this segment of roadway each day. Redecking the old bridge should be completed by October of 2011, Carns said.
Two options were possible when rehabilitating the old bridge; crews could use 11-ft. (3.3 m) lanes with wide shoulders or 12-ft. (3.7 m) lanes with a narrow shoulder, Carns explained. The Federal Highway Administration said no to the varying shoulder widths and so the project consists of 12-ft. lanes with a narrow shoulder. Work on the old bridge is scheduled to be completed in one year.
Also in 2010, About a half a mile of roadwork leading to the new bridge on the Iowa side was completed in 2010, along with retaining walls to avoid impacts to businesses. Some walls were mechanically stabilized walls to help prevent erosion, while on the Nebraska side of the bridge, retaining walls with the look of a rock wall were added using soil nails.
Soil nailing is a method of reinforcing natural soil slopes by installing grouted steel bars (called nails), into the soil slope to increase the shear capacity of the failure surface. The nails are placed thru the potential failure planes; the frictional force developed between the grouting around the nails and the soil provides the required stabilization force.
The function of the nail is to provide tensile resistance; therefore the pull-out capacity of the nail is of major interest. The design capacity is verified on site by conducting pull-out tests in conjunction with the installation.
Segment 2 of the multi-year project is to begin in 2011. Segment 2 begins on I-80 just west of the I-80/I-29 west system interchange in Council Bluffs and continues to just east of Indian Creek. The segment also includes I-29 through the west system interchange, north to and including the Union Pacific Railroad bridge.
This segment includes construction of the “dual, divided freeway” from the west system interchange to Indian Creek; and reconstruction of the west system, 24th Street and Nebraska Avenue interchanges. In Tier 1 it was determined that a “dual, divided freeway” should be constructed along the overlapping section of I-80/I-29. The dual, divided freeway would physically separate through traffic on I-80 from traffic on I-29 and traffic destined for Council Bluffs, Iowa. This is done by constructing four separate roadways (two for traffic in each direction). Each roadway would be separated by a concrete median barrier.
Segment 3, which is expected to begin in 2012, begins on I-80 just east of Indian Creek and continues to a point northeast of the Madison Avenue interchange. This segment includes construction of the “dual, divided freeway” from Indian Creek to the east system interchange. The segment also includes I-29 from south of the U.S. 275/Iowa 92 interchange, north to and including the east system interchange.
Segment 4 begins on I-29 north of the Union Pacific Railroad Bridge and continues to a point just west of 25th Street. Currently, this segment includes the I-29/I-480/West Broadway system interchange and interchanges at 41st Street, Avenue G, Ninth Avenue and 35th Street. Two concepts are under consideration for Segment 4 improvements, both concepts provide direct access to West Broadway from I-29 via one-way frontage roads as was decided in the Tier 1 Final Environmental Impact Statement.
Segment 5, which is expected to be completed in 2036, begins on I-80 northeast of the Madison Avenue interchange and continues to east of the U.S. 6/Kanesville Boulevard interchange. Segment 5 improvements include three lanes in each direction on I-80, and reconstructed U.S. 6/Kanesville Boulevard interchange to a partial cloverleaf with loop ramps. CEG
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