Photo tour: Before building a tunnel, the state builds a pit

(Photos by Nick Adams for WSB)
As the next phase of the Alaskan Way Viaduct Replacement Program intensifies – digging the launch pit for the tunnel-boring machine – dozens of curious people joined a walking tour through part of the work zone last night, and contributing photojournalist Nick Adams was there for WSB. Above, deputy program administrator Matt Preedy (a West Seattleite) was among the project leaders pointing out sights like this –

Our photo tour continues ahead:

The walk began at Milepost 31 (WSB sponsor), the project-info/historic-exhibit center at 211 First Ave. S. (hours and other info here), where the centerpiece is a model of the tunnel-boring machine that’s now under construction in Japan.

Here’s a cross-section:

Now on to the walking tour, which took participants about a mile, round trip, along the bicycle-pedestrian path that parallels the work zone. If you drive 99, of course, you’ve seen the cranes:

But you can’t really appreciate the magnitude of what’s going on till you get out on foot and stop to look:

Chris Dixon from Seattle Tunnel Partners, the joint venture that got the contract to build the tunnel, answered questions:

As you’ve probably heard before, the tunneling machine will be the largest in history – 57.5 feet wide, 300 feet long – so its launch pit has to be of colossal proportions –

The construction of the pit is explained here – 200-plus concrete piles are part of the walls to make sure it’s stable. Last night, among those looking and listening to learn about the 80 x 80 x 400 launch pit, was tour participant Brian Jencks:

If you missed last night’s tour, WSDOT points out you can take a self-guided version too, by checking out signs along the pedestrian-bike path in the area – same path the group walked with Preedy and Dixon last night.

The tour was part of a series of monthly special events presented by WSDOT via Milepost 31. Next month – on October 4th – they’re planning a presentation about protecting buildings during the tunnel’s construction.

sam-c September 7, 2012 (12:34 pm)

we really enjoyed the walking tour – very informative and interesting. also learned about a different u-turn bridge project that would help to alleviate port trucks getting tied up by train building traffic. learned the reason for the very tall steel columns in place between n and s bound lanes…perfect night for it too.

the milepost 31 place is interesting and fun too, hadn’t been before. I just hope the real tunnel boring machine doesn’t break down as soon as the tunnel-boring machine model. ;)

(it has these cool buttons that you can press for it to ‘do things’ but only one of them worked, it seemed)

we did our best to stay out of the way of all the cyclist commuters, and most of the cyclists were pretty friendly and accommodating … only had a handful of them yell angrily- ‘get outta my way!’