The junction of Interstate 35 and Interstate 80 in the Des Moines, IA, area is a major crossroads in the Upper Midwest. Over the next few months, motorists passing through central Iowa at the junction of I-35/80 will see a major expansion in the capacity of the interstate that runs through Iowa’s capital city.
With an estimate of 62,900 vehicles per day in 1999 (with 18 percent of that being trucks), the traffic on old two-lane I-35/80 north of Des Moines is tight. And with a projected 84,300 vehicles per day to come in 2019, it’s apparent that now is the right time to act to improve the corridor.
The I-35/80 project continues an ongoing project in this corridor that started in the mid-80s, widening a 3.84-kilometer (2.4 mi.) segment of I-35/80 to six lanes. The I-35/80 project is the final segment to be completed in the city’s link the east and west mix masters.
Iowa Department of Transportation Project Engineer Deanna Maifield said this is the largest project let in Iowa this year. “Work on Stage One cost $15.5 million,” said Maifield, “and the remaining work has been let for $37.8 million.”
Stage One was completed in 1999. Maifield said work in Stage One included assignments such as building the median section of five mainline bridges (the inner one-third of two separate bridges which are temporarily tied together for staging purposes); installing 24 temporary drainage structures in the median (all with outlet pipe jacked under the existing pavement); placing temporary barrier rails to protect median workers, installing storm sewer and 47 median intakes; lengthening existing pipe; and grading and paving of inside shoulder, paved median, inside shoulder, and temporary pavement. A high fill, exceeding 2 meters (9.9 ft.) through some areas, was required through most of the project.
Stage Two includes placing traffic in the newly constructed median lanes, tying in temporary ramp connections for traffic, tying on to Stage One median bridges and building the remainder of the bridges, grading and paving all lanes, building ramp bridges and a portion of the eastbound ramps, and completing and tying in new eastbound ramps.
Stage Three includes placing eastbound traffic on new outside lanes and westbound traffic in median lanes, tying in temporary ramp connections for eastbound traffic, tying on to Stage One median bridges and building the remainder of the westbound bridges. Stage Three also includes grading and paving of all westbound lanes and completion and tying in new westbound ramps.
Stage Four includes shifting westbound traffic to the new outside westbound lanes, building permanent concrete barrier rail on the median section, and opening traffic to three lanes in each direction.
Maifield said that the first stage of bridge construction was let as separate projects. “The second and third stages were included in the main contract to allow work to progress on both the bridgework and grading and paving according to the staging. The decision to combine these bridge and paving projects was made when we decided to accelerate the project and special intakes were added to maintain drainage during the staging of the project,” said Maifield.
In 2000, unusually warm weather in the Midwest allowed all work an early start in February. But Maifield said that meeting the goal of completing the work this year may require just such luck and good weather — not just in spring, but all year long.
There are many special challenges in working within a major junction of two interstate highways. Maifield cited many complications, including keeping the entrance and exit ramps open as much as possible, tying on to bridges which are under traffic and moving, working within restricted work areas, reduced access for emergency response vehicles, and the problems originating from working at night (to reduce traffic interference).
Maifield said there are several contractors on this project, including Cedar Valley Corporation, the prime contractor for paving; Reilly Construction, the contractor for grading; mainline bridge contractors Jensen Construction, Cramer and Associates, United Contractors; and Longfellow Drilling, which was selected as the contractor for drilled shaft bridge foundations.
Maifield cited several unique aspects of this project. “The staging has been unique, especially the bridges. We are requiring from contractors that two lanes for traffic are maintained in each direction. Also, any lane closures on the Interstate 35/80 project must take place between 8:00 p.m. and 6:00 a.m. between Sunday night and Thursday night. It’s also interesting to note that this segment was scheduled to be under construction for three years. Instead, the Iowa Department of Transportation has placed a $4-million ’no excuse bonus’ on the job for the contractor who can finish the work by the end of this year.”
There were also many subcontracts included in the I-35/80 project, involving relocation of utilities. Most utilities relocations were accomplished ahead of time by separate contracts, except for the water line work, which was included on the main contracts.
The quantities of materials required to complete the I-35/80 construction project include a total excavation of 486,000 cubic meters (631,800 cu. yds.) of rock, 137,000 square meters (178,100 cu. yds.) of PCC, and 19,000 square meters (30,400 cu. yds.) of ACC.
When the I-35/80 project is complete, the junction of Interstate 35 and Interstate 80 will be able to handle the traffic that comes with being a major crossroads — and Iowa will have completed its largest project this year, and brought to a close an overall project that was started in the mid-80s, finally linking the east and west mix masters.
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