When St. Paul officials began making plans two years ago to address cracked pier caps and leaking expansion joints on a heavily traveled bridge linking downtown to the East Side, they figured they could make the fix for $3 million.
But when a consultant this summer discovered that the traffic and structural loads on the bridge's long support arms exceeded federal standards not in place when the bridge went up in the early 1980s, the repair work nearly tripled — to $8 million or more.
The steep jump now has the city weighing the option of building a new Kellogg Boulevard-3rd Street bridge — conservative estimates run from $30 million to $40 million — that would meet pent-up demand for a more attractive and multifunctional structure.
It also raises questions about how a bridge built only 32 years ago could be deteriorating so rapidly.
City Engineer John Maczko said the pier caps were showing pronounced stress, which he said starts with the bridge design — OK in 1980 but considered defective today.
"The bridge itself could not be [built] under today's code of specifications because of the cantilever," which causes stress on the bridge's outer lanes, he said.
The bridge is considered "structurally deficient" by engineers, which doesn't mean that it is unsafe or likely to fall, but instead has elements that need to be monitored and repaired.
Nevertheless, in a state where memories of the stunning Interstate 35W bridge collapse in 2007 remain fresh, MnDOT has taken notice.