I'd LOVE to see their analysis of how they arrive at that number.
My guess is... it's not true and in a large part based on faulty assumptions and bad data.
I haven't done a major railway tunnel update, but I've done a lot of server and data center upgrades that have required 24/7 uptime.
We sometimes would schedule outages down to the minute.
For example, if we had to move a server from rack A to rack B.
The actual "moving the server" might take 5 minutes.
But, the outage might be 90 minutes.
Why?
Items like:
Get full, clean backup
Ensure that space is clear of any items others may have left behind
Ensure existing servers can handle the traffic
Make sure NOC team is in place and briefed
Give adequate time for old server to power down
Disconnect server
ACTUALLY MOVE THE SERVER, including unscrewing old screws, moving, screwing in new screws
Connect cables
Give adequate time to power back up
Since we're in an outage, perform an update on the server
Make another backup
Have NOC perform testing
etc.
Oh and in there, at every step there's a contingency plan of "if this step goes wrong, how do we get back to a running state".
Note the actual MOVE took only 1-5 minutes, but everything else, even when the server was 'up and running' took a lot more time.
So my guess is their "wastes 93% of the time" is based on not understanding the whole process.
For example, it wouldn't surprise me if one of the final steps is, "walk the tunnel from end to end to make sure no tools were left behind" (or perhaps use a motorized cart). The specific method/detail isn't important, but the point is, it's quite possible there's close-out steps that are critical to safety that might take 1-2 hours out of that 55 hours. There's 5% of your time right there!
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