Cordova residents gathered recently to discuss concerns regarding Bridge 339 at Mile 37 of the Copper River Highway. The bridge was closed in 2011 when engineers determined that deep scour of the river bed had exposed the bridge's support piers, making the bridge unsafe. Shortly thereafter, the river eroded the far side of the bridge making Bridge 339 literally a bridge to nowhere.
Many community members said the bridge wasn't being replaced fast enough. The loss of Bridge 339 has had an impact on tourism, subsistence, research stations and related local businesses. Child's Glacier, a popular destination for tourists and residents, is now accessible only by guided charter. As a result, some tourism businesses are reporting losses of 30 percent or more.
The Native Village of Eyak, which has several environmental research camps on the Copper River, now stages support and resupply of camps from the Chitna area, resulting in an estimated loss of $100,000 for Cordova merchants during the summer season for this one program alone.
For other residents, the loss of Bridge 339 impacts access to subsistence resources used to feed families during the winter.
Over the past two years, engineers from the Alaska Department of Transportation have conducted various surveys and studies in an effort to design a replacement bridge. As the research and design phase continued, so did the erosion.
According to Transportation, the road breach on the east side of Bridge 339 has grown from 185 feet in width last fall to approximately 800 feet as of June. On May 30, a camera mounted on Bridge 339 captured more than 50 feet of road erosion in 24 hours.
"If we had already built the new bridge, we would now be in the process of designing its replacement," said Russ Johnson, engineering manager at the state Department of Transportation.
Earlier this summer, state engineers determined to hire a construction consultant to address questions of constructability and verify construction cost estimates.
"The river is changing and we are trying to understand this hydraulically. Our guys have never experienced a river change its alignment this fast and we need more information, more data, to understand what the river is doing," said Johnson.
While the recent changes have raised questions about the design of the replacement bridge, they may be providing solutions to issues that the engineers have struggled with since the bridge closed in 2011.
Ironically, as the other side of the road from Bridge 339 got further and further away some of the construction issues in replacing Bridge 339 may be in the process of being solved by Mother Nature.
"The bigger breach means the river is running with slower velocity and the channel should be filling in making the river shallower" said Johnson.
"The infill means that some of the constructability issues we were looking at could dissolve. If the river is filling in, a temporary trestle bridge to facilitate construction might now be feasible."
Johnson is quick to point out that until more data is gathered, and engineers have a better understanding of what the river is doing, they can't say for certain what the recent developments mean for the design process.
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