IA Bridges Reopen After Contractor Error
Earlier this week, Des Moines, Iowa, officials announced that they would be reopening two bridges after they were shut down last month due to a contractor error, which resulted in the accidental removal of bridge reinforcements.
The west half of the bridge, which spans over Birdland Drive, is in the process of being demolished and completely replaced, while the portion over the Des Moines River is slated for rehabilitation. The city planned to keep one lane of traffic in each direction during construction.
However, on April 15, City Engineer Steve Naber announced that the 2nd Avenue and Birdland Drive Bridges would be completely shut down. The closure resulted after a construction contractor “inadvertently removed portions of the reinforcement for the east half of the bridge,” making it unsafe for traffic and requiring emergency repairs.
“We understand this closure is impactful to 2nd Avenue travelers,” Naber said at the time. “Structural engineers and the contractor are working to reinforce and reopen the east half of the bridge, estimating the east half of the bridge could be reopened back to one lane of traffic in each direction within two to four weeks.”
Des Moines officials said that crews worked for 18 days to reinforce the bridge and pour concrete to ensure travel would be safe on the corridor. Travel was opened for one lane in each direction on May 2 while work continues on the bridges.
2nd Avenue bridge to close for weeks in Des Moines https://t.co/YYEIhLjG3P— WHO 13 News (@WHO13news) April 15, 2022
In an interview with Nabor, he said the contractor has reinforced the bridge by placing four large steel beams underneath the structure to make it structurally safe. The contractor is also reportedly back on schedule for the project.
According to the city, the cost to repair the mistake will be assessed by the contractor.
Corridor Construction Project
The 2nd Avenue Bridge over Birdland Drive was constructed in 1936 and altered and widened in 1986. According to the City of Des Moines, it was determined that it would be more cost-effective to fully replace the structure based on its condition. The bridge stretching over the Des Moines River was constructed in 1935 and widened in 1985, with its condition allowing for rehabilitation rather than replacement.
The bridge project was let through the Iowa Department of Transportation in January.
For the bridge over Birdland Drive that will be fully removed and replaced, the new bridge is designed to be longer than the existing bridge to miss old foundations, but the bridge cross-section will match that of the river bridge. Traffic barrier rails and ornamental handrails will match the river bridge.
However, officials say that the low clearance under the bridge over the road can not be improved. The elevation of 2nd Avenue controls and its proximity to the levee system and existing utilities reportedly make it cost prohibitive.
For the bridge rehabilitation, the current 500-foot-long, five span steel girder bridge will be reconstructed with the bridge deck in the outer two beam bays facilitating new construction of an 11-foot-wide trail along the east side of the bridge and five-foot-wide sidewalk on the west side. New traffic barrier railings and accent lighting will also be added.
For the bridge deck, the structure will be spot-repaired with a new fiber-reinforced concrete overlay. The bridge beams and bearing assemblies will be sand-blasted and painted with a new coating system.
The project is planned to be completed in phases, with the replacement of the bridge over Birdland Drive beginning of March, and the rehabilitation of the bridge over the Des Moines river occurring later this spring. Both are expected to be completed by fall 2023.
Afterwards, the city will also perform select utility relocation, full pavement reconstruction of 2nd Avenue from University Avenue to the Des Moines River and storm sewer installation along the west side of 2nd Avenue. These road projects are expected to be completed by 2025.
A traffic engineering consultant was hired by the city to complete a traffic study of the area to determine if geometric improvements to the street were also needed. The consultant was noted to observe crash trends, existing and future traffic operations and multi-modal accommodations.
Results from the study revealed that 2nd Avenue had higher average crash rates along the corridor and at several intersections when compared to statewide average crash rates for similar corridors and intersections. Additionally, it identified the following issues:
“2nd Avenue is such a vital corridor for our residents and neighborhoods, for our visitors and in our entire metropolitan area,” Naber said prior to work beginning. “It carries about 19,000 vehicles a day. So we'll actually be doing this project in staged construction, which will allow us to keep one lane of traffic open in each direction.”
The bridge replacement and rehabilitation projects are estimated to cost $10 million, while the road reconstruction and storm sewer work (under one contract) are expected to cost $16.5 million. The bridge construction is funded with a combination of funding including Iowa DOT funding, gaming funds and issuance of General Obligation Bonds which are paid by a levy on all taxable property within the City.
Construction kicked off on March 31, with the City of Des Moines reporting that it has awarded 46 construction contracts for public improvements totaling about $85 million. Contracts include bridge improvements, street improvements and stormwater management upgrades.
“We know this construction affects all users of these corridors,” Naber said in the release. “When we went through our budget process in recent years, our residents expressed a huge desire to improve our streets for all users, so we are very proud of this ambitious plan to make those improvements a reality.”