Monday, July 18, 2016

Pretend you have X-ray vision – then, we’ll help you picture a buried bridge

By Kris Olsen

One of Superman's powers is X-ray vision. While there's only one Superman, we want you to imagine you have that same power and peer into the earth with us so you can see an unusual culvert replacement project in Woodinville.

Little Bear Creek, and the culvert that will be replaced in part by building a buried bridge.

Typical culvert replacement approach
Usually, replacing a culvert involves closing a road, digging up the existing culvert and installing a new one. But Little Bear Creek is 30 feet below SR 202/131st Avenue Northeast. The typical approach doesn't work here. That's because we'd need to close the road for about a month and dig up a huge amount of dirt to safely reach, remove and replace the culvert. A month-long closure of the main entrance to Woodinville is neither practical nor something we wanted to put Woodinville drivers, businesses and residents through.

Crews will break through this large concrete wall in order to build a buried bridge as part of a culvert replacement project.

An unusual solution
So our engineers devised another plan: build a bridge underground and then excavate underneath it to reveal the belly of the bridge and a bigger space for Little Bear Creek to pass under the road.

But no matter what words we use to describe how we're going to build a bridge underground, it's still hard to visualize. So, we're going to show you. You just have to picture yourself in waterproof boots, standing in Little Bear Creek, and that you have X-ray vision that allows you to see through a concrete wall and into the earth. Scroll through the building a buried bridge graphic (pdf 3.44 mb) we've created to see how we'll build the bridge.

What the buried bridge at Little Bear Creek will look like.

Work starts Monday
Contractors will start drilling through the top of SR 202/131st to start building the bridge the night of Monday, July 18. We'd recruit Superman, but as far as we know, he doesn't have the power to drill holes into the earth, so we'll have to rely on good ol' fashioned heavy equipment for it.