The arch for the new Illinois-bound I-74 bridge could be completed before the start of summer.
Despite recent high winds, bridge workers installed more arch segments last week. They have raised 24 of the 30 pieces that are required to complete the basket-handle-style arch. Four more arch ribs must be installed before the final section — the keystone — is raised in two connected sections.
Officials from the Iowa DOT have said their goal is to move Illinois-bound traffic onto the new eastbound span by the year's end. The arch must be finished before the driving deck between the arches can be installed and the concrete poured.
"The last few pieces, including the keystone, are the most challenging. Extensive surveying will be done to determine if adjustments to the position and angle of the arch are needed," George Ryan, I-74 corridor manager, said Monday. "We’re working towards closing the arch before summer.”
The eastbound arch is more complicated than westbound, because it must accommodate the additional weight of the bike/pedestrian lane, which will be attached to the downstream side of the Illinois-bound bridge.
Access to the span is made cumbersome by its location between the old bridge and the new westbound bridge.
Ryan, of Wood Environment and Infrastructure Solutions, Inc., also said the slope in the far-right lane leading onto the Iowa-bound span is temporary. Motorists have been noticing the slanted pavement in a section above 7th Avenue in Moline, but that area is part of the shoulder, and the issue will be resolved when the second river crossing opens, he said.
June 20 marks the official start of summer. When the westbound span was completed in November, DOT officials said the second span should take about a year.
In other bridge and bridge-access progress:
• The new 6th Avenue off-ramp in Moline is finished and opened to traffic Friday. The only exit on the old bridge is at River Drive.
• Concrete is being poured this week on one of the Illinois-side spans leading to the new arch, and rebar is being tied on other sections.
• Work is in varying stages on piers in Bettendorf. While some are complete and girders are being set, foundations are being drilled for other piers and some are being filled with concrete.
• Demolition continues on both sides of the river, and excavation is underway on the loop ramp at Grant Street in Bettendorf. The detention pond will remain, Ryan said.
• Temporary plywood decking is in place over 4th Avenue in Moline, and iron workers will begin tying rebar there this week.