Why is Bertha so hard to reach?

The in basket: I see that Bertha, the moribund tunneling machine in Seattle, continues to make news on the TV stations, this time regarding the danger of digging the pit to reach it for repairs.

I felt a little dumb about asking the following question, which I had never heard addressed in all the coverage of the machine’s problems, but I asked anyway. Why can’t they just back it out of the tunnel it dug to get to the damaged boring surface, rather than digging a huge hole. That’s what I do when a drill bit gets stuck.

The out basket: Laura Newborn, media relations manager for the Alaska Way Viaduct replacement project, replied, “The answer to your question is straightforward: The machine can’t move backward because it is building a tunnel as goes. It’s how bored tunnels are dug. So the hole is actually smaller on the back end. She referred me to the Web site https://www.youtube.com/watch?v=guWkPRReUaE, an animated representation of what went on behind Bertha as it moved forward.

One thought on “Why is Bertha so hard to reach?

  1. This is a common question. Bertha cannot go backwards, for the reasons specified.

    In it’s (her) location, she has gone about one tenth the distance she was designed to go. Once a deep enough pit is dug to reach her face, and repair whatever is broken, how much farther will she go before she breaks again?

    I can almost hear Boston laughing.

    Most of that part of Seattle is fill. There are several books about Seattle history, most are fun reads.

    This may well be a new chapter!

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