Thirty-eight years ago when the existing I-80 bridge was constructed over the Missouri River at Council Bluffs, Iowa, Jensen Construction of Des Moines, Iowa, erected the piers, which was a huge project for them at that time. Now, the company has grown to the point where it has the equipment, knowledge and manpower to construct a new bridge in its entirety, in this case, one that is adjacent and just north of the 1970s structure.
“This is fun as far as Jensen is concerned. When the first bridge was built we were qualified to erect the piers, which was a huge project for us at that time. Now, 38 years later, our company has grown to the point we are now able to build the whole thing. From that standpoint it is rewarding for us to see the growth,” said Dan Timmons of Jensen Construction.
The $56 million new bridge will be just under 2,500 ft. (762 m) long, or about .5 mi. (.08 km), and 84 ft. (25.6 m) wide. It is being constructed to match the design of the existing bridge. The design of this new bridge is not unique, being about the 15th crossing over the Missouri River, other than it is just big, Timmons explains.
The existing bridge will remain in place while the new bridge is constructed adjacent to it and will continue to carry two lanes of traffic in each direction. Once the new bridge is complete traffic will be shifted onto it so work to widen the existing bridge can begin. The existing bridge will ultimately carry six lanes of traffic, as will the new bridge.
The new bridge is expected to be completed in 2010, while widening the existing bridge will take place in 2011, under a separate contract that has not yet been awarded. Both bridges and their approaches are expected to be completed in 2011, making it possible at this point to carry six lanes of traffic in each direction, eastbound and westbound
Current traffic counts and future traffic projections indicate the need for more capacity. Currently, the interstate system in Council Bluffs carries 20,000 to 75,000 vehicles each day. Some areas of I-80 handle twice as many vehicles as the roadway was designed to handle, according to information from the Iowa DOT. 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, and that number is expected to at least double by 2030, adds information from the Iowa DOT.
The bridge construction is just a portion of a much larger interstate improvement project. In 1997, the city of Council Bluffs and the Metropolitan Area Planning Agency (MAPA) conducted a Council Bluffs Interstate System Needs Study of the interstate system in Council Bluffs, which showed that many of the interstate’s features do not meet current design standards, guidelines or operational criteria and do not provide adequate traffic capacity.
Then in 2002, Iowa DOT initiated the Council Bluffs Interstate System (CBIS) improvement project to address the issues raised by the 1997 study and develop solutions to improve the Council Bluffs interstate system. The CBIS improvements project is a multi-year effort that will result in reconstruction of the majority of the Council Bluffs interstate system.
In 2006, Iowa DOT 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.
George Feazell, District construction engineer, of Iowa DOT District 4 in Atlantic, Iowa, explains there is a separation in the roadway at I-29 and I-80 so each roadway carries three lanes. As I-29 connects with I-80 at a big systems interchange just east of the new bridge, there is a two-lane ramp that comes around and merges just before the bridge and carries traffic across the bridge with five lanes, Feazell explained. This system will match what Nebraska is doing just across the state border. Nebraska has been working on an improvement project for several years and left the last little gap open until Iowa could coordinate its new bridge construction with Nebraska’s final improvements, Feazell explained.
The Iowa construction project will occur in stages as funding is available and in order to proceed without using all the state’s highway funding, thus hindering other necessary highway projects around the state, Feazell added. The bridge construction is part of segment 1 construction, which began in 2008.
Segment 1 construction begins in Omaha, Neb., just east of the I-80/I-480 system interchange and continues across the Missouri River to just west of the I-80/I-29 west system interchange in Council Bluffs, Iowa. In addition to constructing a new bridge and widening the existing bridge, this segment includes improvements to the 13th Street interchange in Nebraska.
Construction of the new bridge is a key component of segment 1 construction. Jensen Construction has been working on the bridge throughout the winter, even in near zero temperatures, and continuing to pour concrete using a thermal control plan. With the thermal control plan, hot water is used in the concrete mix and heat is piped into the forms so they are warm when the concrete is added, Timmons explained. The forms are covered with blankets to help retain the heat in the freezing temperatures.
About 17,000 cu. yds. (13,000 cu m) of concrete will be needed to construct the bridge and the piers. Cement trucks are brought to the piers in the middle of the river with barges, Timmons said.
During March crews were doing drill shafts and driving steel pilings for land piers and they we’re pouring footings during the cold weather. There are two river piers and this is the time of year to do the work because there is less traffic and less water flow. As long as the Corps of Engineers doesn’t release too much water from the north, a high water level won’t be a concern, Feazell said. “The Corps tells us when they will release water and since we are quite a distance away from the water we have time to plan for it and we can then move further back from shore.” The plan is to have all the river piers done this winter. There are just two piers in the middle of the river, which provides the 425 ft. (129.5 m) span the Coast Guard needs, Feazell said. The bridge deck sits between 70 and 80 ft. (21 and 24 m) above the river.
Sectional barges were transported to the project for use in transporting materials and equipment to the middle of the river. Some larger cranes being used on the project include a 225 ton (204 t) crane, three 65-ton (59 t) cranes, a couple of 100-ton (90.7 t) cranes, a 70-ton (63.5 t) crane and a 50-ton (45.4 t) crane, all of which are sitting on sectional barges in the middle of the river.
The land piers were started last summer and work progressed well over summer and fall, Feazell added.
However, about three weeks of construction was lost last summer, 2008, due to high river levels and cold temperatures, Timmons said. “I don’t think we lost any ground that we can’t make up. We have until 2010 to finish so we have 17 months or so to catch up. As we get the piers built the flooding won’t impact us as much as it did when we were working closer to the water.”
To stay on track, concrete pours on the bridge decks will have to begin this summer and fall, 2009, Feazell said. “The contractor (Jensen Construction) wants to set steel this spring so they can start the deck pour this summer.” Subcontractor Kramer Associates of Des Moines, Iowa, a bridge contractor, is working on the Nebraska side erecting steel. Subcontractor Iron Works of Nebraska City, Neb., a rebar tying company, is handling the rebar tying. Grading on the Iowa side is being handled by Riley Construction of Decora, Iowa.
Deck pours are rather efficient at 500 cu. yds. (382 cu m) a day. The deck pour pattern has not yet been decided. “We’re keeping an eye on the substructure and once we’re past the pier construction we will look at the deck pour plan,” Feazell added. Deck pours are done so the deck is not loaded unequally. There is a systematic way to plan and work across the bridge. Some contractors plan so they can pour right next to the previous section or they use a quilt pattern and skip ahead. Most contractors work their way across the bridge, pouring half at a time, and then come back when the concrete has strength and pour the other side, he explained.
The second segment of construction is slated to begin in 2012, though the design is still in the planning stages. Work will begin 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. This segment also includes I-29 through the west system interchange, north to and including the Union Pacific Railroad bridge. Key features of the Segment 2 improvements include:
• construction of the dual, divided freeway east of the west system interchange;
• three lanes in each direction on I-80;
• a minimum of two lanes in each direction on I-29;
• auxiliary entrance/exit lanes as needed on I-29;
• three lanes in each direction on I-29 north of the west system Interchange;
• reconstructed diamond interchange at 24th Street similar to the existing configuration;
• reconstructed folded diamond interchange at Nebraska Avenue similar to the existing configuration;
• reconstructed west system interchange; and
• reconstructed Union Pacific Railroad bridge.
Segment 3 also is expected to begin in 2012 and begins on I-80 just east of Indian Creek and continues to a point northeast of the Madison Avenue interchange. Design plans are still being developed. Key features of the Segment 3 improvements include:
• construction of the dual, divided freeway west of the east system interchange;
— three lanes in each direction on I-80
— a minimum of two lanes in each direction on I-29
— auxiliary entrance/exit lanes as needed on I-29
• three lanes in each direction on I-29 south of the east system interchange through the U.S. 275/Iowa 92 interchange;
• three lanes in each direction on I-80 east of the east system interchange;
• reconstructed folded diamond interchange at South Expressway similar to the existing configuration;
• reconstructed diamond interchange at Madison Avenue similar to the existing configuration;
• reconstructed partial cloverleaf interchange at U.S. 275/Iowa 92 similar to the existing configuration; and
• reconstructed east system interchange, including straightening of the I-80 alignment through the interchange.
Two possible concepts for a fourth segment also are being considered. Segment 4 basically, will begin on I-29 north of the Union Pacific Railroad Bridge and continue 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. 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.