Millennium Line - Broadway Extension: Planning & Pre-Construction

[queetz@home]

A very interesting article on the Broadway Line from 24 Hrs Vancouver I'm surprised it hasn't been posted yet....

Mayors choose pricier Broadway Subway option

Some interesting tidbits

“Cut and cover gives you the ability to open up multiple holes in the ground, multiple holes in the ground, multiple trenches — so if you need to accelerate the schedule and you wanted to throw a lot of workers into the bunch, you can accelerate cut and cover by just opening more holes,” Eberhardt said.

“When it’s a machine — you’re limited to what you can do within the machine.”

I guess ultimately, this could be the reason why cut and cover was chosen (likely behind the scenes with collaboration with Falcon) for the Canada Line...they needed it built ASAP and you have more control over that method. As we now learn with Evergreen Line, tunneling has a lot of uncertainty, and the Canada Line could have been delayed for the Owelympics...

One question is whether the soil conditions at the Evergreen Line tunnel route is similar to what can be expected along Broadway. And the answer is yes, they’re very similar, according to John Clague, a Simon Fraser University professor who’s also president of the Association of Professional Engineers and Geoscientists of B.C.

So it can be expected that the Broadway subway would at least face some of the challenges Evergreen Line crews had to deal with.

“During the ice ages, virtually the entire province was covered by an ice sheet … the ice sheet was flowing across the ground, partly eroding the ground but also depositing a layer of till,” Clague said.

The whole region is generally made of the same stuff that sits atop a bed of sandstone. It’s called glacial till — a loose mix of everything from sands, gravels, silts and clays that Clague described as a “complex layer cake,” and how thick the material is can change from spot to spot.

Hmm...sinkholes on Broadway? That should scare some peeps since hydraulic fluid from a bus is enough for UBC students to consider a horror show scenario...