Watch this video clip (Windows Media) Length: 3:26

Text transcript from the video "Edgewick Bridge"

Narrator

The Edgewick Bridge is located east of North Bend on 468 th Ave SE, spanning the south fork of the Snoqualmie River.

In a unique construction arrangement, a temporary bridge was erected right next to the old bridge to allow traffic to continue to use the roadway without a detour.

Dee Gilmore/KCDOT Roads Engineer says:

We have a temporary one lane bridge that goes across the river on the same structure as the work platform for the contractor, then we have a temp. traffic signal set up so that on each end you have a red light-green light cue that lets traffic go through, it seems to be working really well.

Narrator

On this day crews are drilling the shafts for the new bridge pillars. This construction technique, which wasn't available 50 years ago, will give the new bridge the foundation to outlast its predecessor.

Dee Gilmore/KCDOT Roads Engineer says:

In a nutshell it's considerably stronger. What's holding up the existing bridge right now is two old concrete piers on spread footing and then wood pilings behind that for the approach span and the wood pilings have rotted out. If we put new wood pilings back in, we would be seeing the same problem down the road. So what we're going to see with these shafts is a bigger, better foundation than what's there now to support the new bridge, it's a slightly longer span so that's also a consideration in the structural aspect of the design.

The new drilled shafts are 55 feet deep and six feet in diameter. They're also considerably farther back from the river than the foundation, a change made to improve stability and appease mother nature.

The existing foundation piers are actually in the water and debris has a tendency to come along and get hung up on that, there's also a way that the river comes around the corner and it gets swirling through there and creates pockets that may undermine a foundation, so with going with the deep shafts that far away from the water, we should eliminate any problems with that. Mother nature should be able to flow through there just like she intended.

Obviously when you're building near a river there are all kinds of environmental concerns and you want to keep anything that is going to create silt, including concrete which has worse properties from getting to the water. So there is a lot of effort when handling the concrete materials to keep them out of here. The dirty water from the drilled shaft operation for example is going into banker tanks that are over on the other side and in those tanks they'll be allowed to settle out and the dirty materials will be hauled out as opposed to just being released. And then there's permit limitations as to the timing, we could not be in the water until March first, to construct the temporary bridge and platform and then it has to be out of the water by Nov. first and that's a permit requirement. So we have that time frame in which to construct the temporary bridge and platform and construct the new bridge and then be done.

Narrator

The new bridge will be longer and wider than the old bridge, with better visibility, but will share some of the characteristics of its predecessor. In addition to being in the same location, the new bridge will also be built of steel with a similar look and design…keeping the rural feel of the Edgewick Bridge and surround area intact.

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