Up the river without a solid bridge

A few miles upstream from the ill-fated I35W bridge over the Mississippi River stands the 102-year-old Lowry Avenue Bridge. It’s crooked, but still safe to drive across, Hennepin County officials say.

Built in 1905 and reconstructed on the original wooden pilings in 1958, the bridge was closed three years ago when one of its mid-river supporting piers was found to be tilting 11 inches out of plumb. The old pilings are “tired,” said Jim Grube, the county engineer.

Using hydraulic jacks, crews lifted the bridge superstructure off the concrete pier and inserted a new steel bearing assembly, then eased it back onto the still-leaning support structure. Since then, 15,300 vehicles a day have crossed the reopened bridge without incident.

They’ll have to keep risking the trip until at least 2011 under the most optimistic funding scenario for replacing the bridge, a $109 million project that Grube said will be needed sooner or later – preferably sooner. But that depends on securing nearly $100 million in special grants from reluctant state and federal governments, he added.

Hennepin County is offering to put up $12 million for the project. That would be its entire one-year construction allotment from state gasoline and vehicle taxes going to a less-than-half-mile stretch of County Rd. 153 over the Mississippi and the Canadian Pacific Railway. The Hennepin County road system stretches over 1,617 lane-miles and 140 bridges, some deemed more hazardous than the leaning Lowry.

Like the 35W span, the Lowry Bridge is rated as structurally deficient and “fracture critical,” meaning that if one of its support members fails the whole thing comes crashing down. Its sufficiency rating on a scale of 100 is 43. Anything under 50 – the rating of the 35W Bridge the day it collapsed – means ready for replacement.

County inspectors check the Lowry Bridge at least once a month, Grube said, adding that “there’s no problem at all.”

Maybe not. But there surely is a problem with ongoing, dedicated state funding of local roads and bridges throughout Minnesota via user fees on fuel and vehicles. A recent study for the Minnesota Department of Transportation by state economist Tom Stinson and a University of Minnesota colleague found that real per-capita state highway aid to counties fell by 2 percent from 1993 to 2003. And that was before the doubling of road and bridge construction costs over the past four years.

For Minnesota’s cities, the Stinson report had even worse news: “The buying power of aid received by cities in 2003 is 27 percent less than in 1993 when adjusted using the construction price deflator.”

Meanwhile, if Hennepin County officials think the Tilting Trestle of Lowry is enough of a special case to warrant a $100 million cash infusion from higher levels of government, they may be in for a disappointment.

Stepped-up state structural inspections in the wake of the I35W disaster have led to closures of five bridges in rural Minnesota and critical findings on 10 more. MnDOT said those spans have beam cracks, severe corrosion or worn underpinnings.

And in west-central Kandiyohi County, commissioners have approved a plan to replace nine deficient county and township bridges within three years. They’re hoping the state will borrow money to pay for eight of them.