Saturday, November 03, 2012

Lambert Slough Bridge

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The Lambert Slough Bridge is one of the more obscure destinations the ongoing bridge project has visited (so far). Lambert Slough is a small side channel of the Willamette River, separating Grand Island from the west bank of the river, and this little bridge is the only way on or off the island. I figured I ought to at least take a photo of the bridge on my way to the state park on the island, since I'd already established that this project included bridges on the Willamette at least as far south as Salem, and bridges out to islands were fair game, since I'd done the Sauvie Island Bridge. So I pretty much had to do this one for the sake of completeness. And completeness it is, since with this I think I've covered every bridge as far as Salem, plus one in Eugene. Except for the Champoeg Road pipeline bridge near Newberg, and I've more or less convinced myself that it doesn't count.

As with the OR-219 bridge, there's no page for this bridge at BridgeHunter or Structurae or any of the usual bridge fan sites, but there is a page about it at In which we learn it's a reinforced concrete deck girder bridge, built in 1964, and any historical significance was "not determinable at this time" as of 2009. At that time it was given a 64.2% structural sufficiency rating, which is decent (certainly compared to the Sellwood Bridge's 2% rating) but down from 87% in 1991, probably due to an increase in traffic -- although 428 vehicles per day still counts as light traffic, I think.

As mentioned in my earlier Grand Island post, the island is threatened by a proposed gravel mine, which is currently working its way through the courts and the county permit process. Since this bridge is the only way on or off the island, gravel mining would mean a steady stream of big gravel trucks. The county commissioned an engineering study of the bridge in 2010 that concluded the bridge could handle the truck traffic, although not everyone's pleased that Yamhill County would be on the hook for higher maintenance costs due to increased wear and tear.

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