Seattle tunnel construction avoided costly mistakes of Boston's Big Dig

King 5 News ^ | January 17, 2019 | Amanda Grace

[gogeo]

The hills in and around Boston were pulled down to create the fill. Tough work in the 19th century.

Same thing in Seattle. The tunnel and the viaduct are in fill.

[Tolerance Sucks Rocks]

They used one of those large round visitor ships from the V series to suck all the water out of the harbor so they could then cut and cover.

[21twelve]

LOL. I had my doubts on the tunnel due to the variable geology. Some of the tunnel route is the hydraulic fill of loose sand. Other portions are a wide variety of overburden dumped by the glaciers (gravel, clay, silt, etc.) I think it was something like ten different types of materials they had to dig through. They did have some issues with subsidence due to when it was stuck.

[LanaTurnerOverdrive]

The viaduct was 8-lanes.

The viaduct was SIX narrow lanes....and it had downtown exits, unlike the new tunnel.

[rockrr]

Thanks for the correction. It’s been years since I have ventured into the valley of the shadow...

[moehoward]

Now they are removing buses from the tunnel because they slow down the trains.