Plans for the replacement of the Winona Highway 43 Interstate bridge have been delayed for years as officials investigate the potential to fix up the historic structure rather than replace it. Three rehabilitation options, although MnDOT admitted they are flawed, were recently presented to the Minnesota State Historic Preservation Office (SHPO), one of the final steps in the rehabilitation consideration.
SHPO officials reviewed the three concepts and sent comments on each back to the Minnesota Department of Transportation (MnDOT) on Friday. The letter from SHPO included questions about the options, as well as identifying a preferred rehab plan. As for two of the three options that would widen the approach to the bridge on the Minnesota side, SHPO questioned the effect they might have on Winona’s historic downtown area -- as well as how city leaders might react to having “a highway ramp dumping into their downtown.”
The options identified by MnDOT officials for bridge rehabilitation carry with them some major drawbacks, including the need for bridge closure during construction, as well as questions about the risk of further deterioration of a structure deemed fracture critical -- lacking redundancy in components that, if they failed, could cause the bridge to collapse.
None of the rehabilitation options would address all of the bridge’s structural concerns, according to the MnDOT report. In fact, risk associated with rehabbing intricate steel deck truss spans is listed as “very high,” posing problems with simply adding new plates over existing, corroded steel components that would continue to rust and degrade underneath the patch job, which would also make it harder for inspectors to identify future corrosion.
Each of the options also includes consideration of long-term bridge closure because without it, the construction timeline would be significant.
The first option would not alter the footprint of the bridge, simply strengthening all components as feasible and replacing the concrete deck. This option was identified as the preferred option by SHPO, but it would not address the projected traffic needs or widen the span at all.
The other two options would both reconfigure the initial components of the bridge on the Winona side, including widening the bridge from its touchdown to the spot on the bridge where the overhead trusses begin (approximately one half block from the river’s edge). That area would be widened from the existing width of 48-58 feet to 70-74 feet.
Both options would also reconfigure the intersection at Fourth and Winona streets to provide for turn lanes and a wider intersection.
Widening that intersection was identified by SHPO as a concern. “In terms of approach work (B and C), it is difficult to understand what effects the widening and traffic improvements will have on the bridge or downtown area, because the plans sent to us are so tiny,” reads the SHPO comment letter. “However, it does appear that the bigger radius corners shown will be out of place in the surrounding residential area. How might this affect downtown historic buildings and districts? What is the City/[Heritage Preservation Commission] reaction to a highway ramp dumping into their downtown?”
The third option, along with widening the approach and intersection, would also include replacing the bridge approach on the other side -- the area where turn lanes take motorists to Dick’s Marine and Latsch Island, although it would not include widening or altering the geometric alignment of the section.
All options would include rehabilitating trusses and other bridge components, but MnDOT’s report indicates concern about the inability to actually replace certain components without completely dismantling the bridge to do it.
“Risk associated with rehabilitation of intricate elements and connections of the steel deck truss spans is very high,” reads the report. “It is impossible to remove all corrosion, seen and unseen, without disassembling the entire steel deck truss structure and removing all corrosion before reassembling the structure. The deck trusses are significantly deteriorated and this work would require the trusses to be taken off the pier supports, placed on the ground and disassembled, rehabbed, and then placed back on their pier supports. A substantial number of members and gusset plates may need to be replaced with new material.”
The two options that would widen the touchdown and approach on the Winona side would help alleviate the projected traffic concerns, although the first option that would merely strengthen components and not alter the width of the structure would not, and the MnDOT report indicates that traffic levels by 2038 would be unacceptable and create traffic jams under that scenario.
All three options in the report include statements suggesting long-term bridge closure may be necessary. “Performing the rehab project under traffic would be very difficult and would add significant time to the construction schedule,” reads the report. “Some phases of rehab work cannot be performed under traffic and would require temporary closure of the bridge. Long-term traffic closure of the bridge and rerouting of traffic via a detour or temporary bridge would allow the most efficient rehab project because segments of the bridge can be removed.”
SHPO’s first question centers on the deck replacement included in all three rehab options, wondering why it needs replacing.
MnDOT project manager Jai Kalsy was unavailable for comment. A Winona Post report earlier this year identified MnDOT data that showed the concrete bridge deck is suffering wear and tear due to overweight truck traffic, and that the 20-year design life of the concrete deck had been reduced by a full four years because of it. That reduction in deck design life estimate is from MnDOT data from January. Estimates from MnDOT bridge scales from March changed the reduction in the deck design life to two years, backing off on earlier reports that showed more damage occurring.
SHPO also questions replacement of certain components of the bridge considered to contribute to its historic appearance, including lacing and batten, and the replacement of rivets with bolts. SHPO comments also reject the option that would change the bridge the most -- altering the approach at Fourth and Winona streets and replacing components of the structure at the Latsch Island touchdown, asking that it not be considered unless the other two options are eliminated.
MnDOT’s rehabilitation study can be viewed at its web site. Click on “District 6” to find the Winona bridge project page.