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The end of an era
Narrator Says:
It’s not exactly the Golden Gate, but the Mt. Si Bridge has its own story to tell.
The story starts where the bridge was born, not in North Bend where it is now, but about 36 miles southwest of its current location in Buckley.
The Mt. Si Bridge was once half of a two-part span called the Buckley Bridge and provided transportation access over the White River.
Interestingly, what happened to the other half of the Buckley Bridge remains unknown.
The Buckley Bridge was a boon to the logging industry, which peaked in the Snoqualmie Valley in the early 1900’s; around the time the bridge was built.
Its design is rare nowadays, but was very popular in 1914, which is when county records indicate work finished on the structure.
A pound of bacon cost a little over a quarter, and a loaf of bread was about a nickel.
Mt. Si’s structure is called a Pratt Truss, named after the two men that patented the bridge’s design. It’s also held together with 36 of these steel pins.
Though the bridge has held up just fine over the years, the pins are actually a bit of an Achilles Heal for the bridge.
King County Engineer Julia Turney Says:
The pin connections while unique in the development of bridge construction in the United States, also represent a weakness in the bridge, in that in one pin failing, the entire bridge can fail, so that the piers themselves that the bridge rests on, are original to a 1930’s bridge in this location.
And the bridge itself is scour critical from flooding from the bridge, all things will be corrected by the new construction of the new structure.
Narrator Says:
The new structure, seen in a computer rendering here, will replace the Mt. Si Bridge, which would hit the century mark in 2014.
The bridge is showing its age, and its dated design.
Mt. Si offers no pedestrian access, the new structure will. The existing bridge is only 19 feet wide from curb to curb, a width that doesn’t allow today’s bigger vehicles the safest access over the river.
A new structure will be an opportunity to improve the sole access those living on the north side of the river have to their homes, and replace a bridge that’s given travelers in King County more than their money’s worth.
King County Senior Engineer Gwen Lewis Says:
The condition of this bridge right now is there are several areas that show signs of rust, the deck has corrosion, the bridge is 92 years old, right now the timber supports are deteriorating.
And portions of the bridge under the asphalt pavement, is a metal deck, and that metal deck is relatively soft in nature, and what happens right now, is when heavy trucks do come across the bridge, it results in cracking the asphalt pavement and that cracking requires a great deal of maintenance from the Roads Services Division.
Narrator Says:
This passage over the middle fork Snoqualmie will step into the 21st century, marking the end of the Mt. Si Bridge’s useful life.
During construction, transportation over the existing bridge will only be minimally impacted if at all.
It’s a structure that’s seen this region of the northwest come to life and change much over its near century of service.
Even though we can no longer head to the story with 30 cents today and walk out with a pound of bacon and a loaf of bread.
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