Viaduct for Dummies: It's the pits in SoDo, and other transpo-nerd news

A giant auger drills holes to create the launch pit

Perched on the edge of the pit as we are here at Seattle mag, we never tire of watching the action–-giant, weird-looking machines shoving around enormous piles of muck; huge, Mad Men-contraptions thundering around behind twisted bales of metal; and what is that curtain hanging from the shreds of the Viaduct? Some days, I can barely contain my excitement, especially when something new is happening (like over at the 520 project, but more on that in a minute).

This weekend's Viaduct closure (from 11 p.m. Friday, April 6, to 5 a.m. Monday, April 9) will allow crews to reinforce the standing Viaduct section between South Washington and Columbia streets (where the tunnel boring machine will pass through, 80 feet below), wrapping damaged sections with reinforcing fiber, and building underground walls to shore up the Viaduct's foundation. You know, so we can still drive on it while the TBM is churning away underneath.

You might also notice piles showing up in the lot just west of CenturyLink (photo above); some 200 or so of these bad boys will create the walls of the launch pit, from which the 5,500-ton tunnel boring machine will begin its journey into our city's bowels, some time next Spring.

Meantime, 520 bridge-building progress continues; WSDOT just released cool constuction plans and renderings of the new bridge. Very cool: The pylons are reminiscent of the Empire State Building, complete with light show! Very Gotham. Since construction barges are stationed under the eastern highrise, the drawspan will now have to open to let tall boats through--something that will require occasional 30-minute bridge closures. WSDOT promises to keep that to a minimum. That might be some consolation to those who pay big bucks to use that bridge.