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Our Proposal: A New Front Door for St. Louis

Cost: A boulevard is the least expensive option.

Removing the depressed and elevated lanes of the former Interstate 70 through downtown and replacing them with an at-grade boulevard would be the least costly alternative to other proposed solutions, both in the long and short terms.

Aging infrastructure of I-70
The route for the new Memorial Drive runs 1.4 miles along the existing I-70 right of way from the Poplar Street Bridge to Cass Avenue. Construction of the boulevard involves mostly demolition, fill and paving at grade, plus minor costs for cosmetic improvements and safety equipment. Another recent local roadway project provides an easy means of estimating an approximate cost for the project.

Final costs for the new Highway 40/64 were $524 million for 10.5 miles of work, including more than 25 new bridge structures and the 170/64 interchange-an average cost of about $50 million per mile. Assuming similar pricing for the new Memorial Drive, the 1.4 mile boulevard will cost approximately $70 million. This estimate is probably high because there will be no new bridge structures included in the project. Maintenance of the boulevard will cost no more than any other prominent City street.

The 2007 Danforth Foundation report estimated the cost of the previously proposed "Lid" concept—which is functionally a tunnel—at $87 million. This design spans just three blocks of the 20 block problem, leaving the elevated lanes to the north, the transition areas, and flyover ramps to the south in place, doing nothing to connect those areas, including the Washington Avenue corridor, with the river. Post 9-11 guidelines require a subgrade surveillance area adjacent to a traffic tunnel. This would require tearing apart a portion of the western side of the existing Arch Grounds for its construction. In addition, the proposed tunnel would require $900,000 annually for maintenance, staffing, and operation, meaning $18 million additional dollars will need to be raised to finance the first 20 years alone. Compared to these figures, $70 million for a 1.4 mile new Memorial Drive that offers a solution to our connection problems and provides an opportunity to return land currently used as roadway to the tax rolls is a much better value.

Doing nothing also has an economic cost. The depressed and elevated lanes of Interstate 70 were constructed in the early 1960s. As this infrastructure ages, the maintenance expense increases. In February 2010, KSDK ran a series of reports about the physical condition of the aging interstate bridges Downtown, including the Walnut Street bridge, the ramps to the Poplar Street Bridge, and the Broadway bridge over I-70. The series also covered concrete crumbling from the Highway 40/64 viaduct which is a few years younger than the I-70 structures. These problems will continue to escalate in frequency, severity and cost as time passes. We are at a historic junction of need, civic desire, and opportunity. The time to address all of these issues with a unified solution is now.

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