Although replacement of the Highway 61 Mississippi River Bridge at Hastings, Minnesota, is now planned to begin during the 2010 construction season, the Minnesota Department of Transportation began a painting and repair project this construction season.

Because the existing structure will remain in service for several more years and will likely be used during construction of a new river crossing, repair work is necessary to keep the structure in good serviceable condition. A review of the scheduled repairs led to a reassessment of what repairs are necessary to keep the bridge operating until it is replaced. The review found some areas of the project that could be scaled back, and MnDOT reduced the construction timelines and impacts to traffic.

Department crews performed a thorough inspection from April 7–18, and then began preliminary work on the 1,800-foot bridge in mid April.

Crews installed a temporary signal system in April at the intersection of state Highway 55 and County Road 42 in Dakota County. The signal will smooth traffic flow by improving left-hand turns from Highway 55 onto County Road 42 and from County Road 42 to Highway 55.

Repairs that began on abutments, piers and beams beneath the south end of the bridge were completed in early May. Additional work began during the first week in May includes strengthening the shoulder of southbound Highway 61 to carry emergency vehicles; other authorized traffic were allowed to bypass traffic queues during single lane traffic later in the spring.

The entire project swung into full gear in early May with traffic restricted to a single lane across the bridge. A signal system at each end of the bridge regulates traffic to take turns crossing the bridge from each direction. Cross streets on the south end of the bridge between Tenth Street and the river are closed to cross traffic, although emergency vehicles have access across the highway at Fifth Street.

Two short-term weekend closures of the bridge and a detour were necessary to remove, repair and replace bridge bearings. Years of weather beating on the bridge has taken a toll on the bridge, and paint has worn from the steel members of the deck causing rust and corrosion. Other wear and tear on the bridge will be repaired during the five-month project.

Major work includes:

• Painting all steel members of the bridge from below the bridge deck to three feet above the road;
• Patching and repairing about 5 percent of the concrete deck;
• Replacing a section of sidewalk on the northeast side of the bridge;
• Replacing 15 expansion joints in the deck and installing new expansion seals used to prevent water from reaching the steel beneath the bridge deck;
• Rebuilding deteriorated curbs on the entire structure;
• Removing, repairing and replacing bearings on several piers. The bearings allow the bridge to move with expansion and contraction.

Rainbow Inc., a Minneapolis paint contractor, erected a safe-span platform under the bridge deck to begin abrasive blasting that removes corrosion and old paint. Containment tarps covered the area from under the deck up to three feet above the bridge to keep dust within the work area according to rules set by the Minnesota Pollution Control Agency.

Dust is blown into a container set on the bridge deck. Mike DeBuhr, industrial division manager at Rainbow, said employees applied three coats of MnDOT-specified paint on the newly blasted steel that will preserve the bridge until it can be replaced. The last time paint was applied to the Highway 61 Bridge was over 20 years ago.

Blasting and paint work covered 1,000-feet of the span, from Pier 5 to Pier 8, said DeBuhr. The repair and paint work will be completed by the first week in August.

In addition, an outdated inspection vehicle that rides on rails beneath the bridge trusses will be removed because it does not work and is not needed.

MnDOT continues to use computer modeling to predict traffic flow, but the signal system's timing will be adjusted to minimize delays for commuters. The department will continue to monitor traffic during the project and make any necessary adjustments while work is underway. MnDOT also made special efforts to reroute traffic to other state highways and lessen the delays to motorists, but delays were inevitable during the project.

The bridge is currently listed in fair condition, and all primary structural members including piers, deck, beams, and trusses are sound. However, the bridge is considered functionally obsolete because of the narrow roadway and the less-than-standard clearance for vehicle traffic between the roadway surface and the top of the truss.

Information about the project will appear in local media and newsletters throughout the work. Additional information about the Highway 61 Hastings Bridge and next year's work is available at http://www.dot.state.mn.us/metro/projects/hastingsbridge/index.html.