© Joe Szurszewski, Courtesy of HNTB
Historical Consistency The rehabilitated Third Avenue Bridge includes changes that meet current safety and engineering criteria while preserving its important features, structural integrity, and historic significance. Original design details were reinstated on the cap beams. Durable, updated lighting speaks to the past and respects the property’s historical aspects. The ornamental concrete balustrade railing placed on the bridge in 1939 and restored during the recent rehabilitation was enhanced to narrow the gaps between the rails. This change adheres to today’s safety standards while fitting aesthetically with the railing’s overall nature. Collaboration with local and state agencies, historical experts, the contractor, a peer reviewer and teaming partners was key to delivering a revitalized Third Avenue Bridge, which reopened on October 28, 2023. “The rehabilitated Third Avenue Bridge is an example of MnDOT’s stewardship of the state’s historic resources,” said MnDOT Project Engineer Christian Hoberg. “The team has worked to understand the roadway needs, made investments to support all users and ensured there was no change in the traffic loads the rehabilitated bridge could carry. Without creating any adverse impact to the span’s historic designation, the Third Avenue Bridge will continue to serve downtown Minneapolis as it has for the last 100 years.”
© Joe Szurszewski, Courtesy of HNTB
separating the deck from the cap beams and installing elastomeric bearing pads to allow improved deck movement. This necessitated more headroom between the deck and an existing 36-inch city water main running below the bridge, requiring the two north concrete beam spans to be raised. Tower cranes, which limited loading on the bridge, allowed for a downstream access lane so the bridge could be constructed in phases. The final construction staging plan integrated tower cranes and temporary superstructures to enable concurrent construction in multiple areas. Although a full closure was necessary for a period of time, the project team kept the bridge partially open for as long as possible, maintaining one open lane in each direction for six months. An additional dynamic, dedicated transit lane that allowed buses to carry passengers into downtown Minneapolis in the mornings was reversed in the evenings to permit bus passengers to exit downtown.
SUZE PARKER is a public relations consultant who frequently writes about transporta- tion infrastructure projects.
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December 2023 csengineermag.com
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