August 2, 2007

Bridges There and here

As we mourn the loss of life in the bridge collapse in Minnesota thoughts must travel to a bridge much closer to home. The immediate replacement of the Bonner Bridge between northern Dare County and Hatteras Island has been the topic of a lot of talk and very little action. Some may be wondering about the current condition of the bridge. I found a report from Dec. of last year. In summary in it says:
The Herbert C. Bonner Bridge is in advanced stages of deterioration and is nearing the end of its lifespan. The bridge is anticipated to be replaced within the next ten years. The findings of the NBIS inspection and in-depth assessment are summarized as follows:
1. The bridge, in its current state, is safe for use by the traveling public and does not require any weight limit posting. However, due to the advanced stages of deterioration, replacement of the Bonner Bridge within the next ten years remains a necessity.
2. Delamination, spalling, and cracking are widespread and the bridge had an overall NBIS rating of “POOR”.[emphasis added]
3. Testing indicates that the concrete is generally of good quality and strength. However, chloride ions above the corrosion threshold exist to a depth of 4.5” in the columns and pile caps; therefore, active corrosion is occurring and will continue to accelerate.

The report details the severe deterioration of sections of the bridge. You have to wonder if this tragedy will prompt any action. I don't have much hope myself. The safety issue seems to be secondary to so many involved in the debate. Lets hope it doesn't take a tragedy of this scope prompt action.


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