A $100-million funding gap has forced the Minnesota Dept. of Transportation to delay major portions of Duluth’s Twin Ports Interchange project by a year.

Originally budgeted at $343 million and awarded to the joint venture of Ames Construction and Kraemer in the summer of 2018, the already challenging three-year reconstruction of the I-35/I-535/Highway 53 interchange has grown in complexity and cost as multiple engineering firms have tackled a host of site condition unknowns. Many arise from the project’s location in a congested former industrial area, contributing to its unofficial “can of worms” nickname.

According to MnDOT, most of the soil and water in and around the project area are contaminated, requiring special handling and treatment. Other cost drivers include geotechnical challenges associated with the poor soil mixture, utility relocations culvert replacements along two creeks, railroad work, and maintenance of diverted traffic on an adjacent highway. In addition to a limited work area, the interchange provides Ames/Kramer with limited storage and laydown space, further complicating material delivery and handling logistics.

With cost estimates approaching $442 million, MnDOT elected in November 2019 to postpone replacement of the Highway 53 bridge across the Lincoln Park neighborhood, and reconstruction of the nearby I-535/Garfield Avenue interchange. Work on the I-35/I-535 interchange is expected to begin later this year.

By deferring construction of the project’s major elements until 2021, MnDOT hopes get a better handle on these issues and determine the most cost-effective means of dealing with them, while also staying as close as possible to the original planned cost. The project could also receive additional funding from the state legislature.

Constructed in the 1960s, the intricate network of more than 30 bridges carries approximately 80,000 vehicles each day. In addition to improving safety, the project will improve overweight permitted freight trucks with direct access to Duluth’s port and intermodal facilities.