WSDOT says they don't have enough data to know for sure whether they can get Bertha back on schedule. Crosscut's analysis is more conclusive.
By Matt Fikse-Verkerk, January 27, 2014
The restricted flow of data and information from the Washington State Department of Transportation (WSDOT) has
hampered schedule analysis of Seattle's deep bore tunnel project. WSDOT
said "it is too early to speculate on the schedule" earlier this month
and is sticking to that talking point, with a spokesperson telling
Crosscut today that "it’s too soon to say if the end date for tunneling
will be revised."
But estimating project schedule impacts is vital when a megaproject
with enormous financial and political implications faces a crisis.
Crosscut has obtained daily tunneling data from WSDOT and performed
basic analyses that show that finishing tunnel boring within the
original 14 month schedule, which called for digging to be done around
September of 2014, is now nearly impossible.
In tunneling, two fundamental project measures are utilization and
production. Utilization is a measure of a TBM's "uptime" versus
"downtime." The machines are vast and complex and a large part of the
challenge is to keep them running – and digging – as much as possible.
The higher the utilization, the more effective the project is at getting
digging done. A second fundamental measure is production, which is the
rate that a tunnel machine can dig when it is running. High rates of
production show that a project team has learned how to optimize machine,
crews and techniques for the conditions being encountered.
Tunnel project managers track and calculate utilization and production
rates with detailed, high resolution data logged by minute, hour, shift
and many more slices. For this analysis, we used the coarser daily data
at hand, which nonetheless reveal the schedule implications of the
Tunneling drives are usually slow at the start and increase as things
get dialed in. But at a certain point, low utilization (machine uptime)
can bite a schedule so hard that no realistic rate of production
(digging) can catch up to the original schedule. At that point, the
original schedule is blown and it's time to chart a new one.
That is where Bertha is now, according to the data.
Bertha's daily utilization since being launched has been a crushingly
low 25 percent through January 27, 2014. That means 75 percent of the
182 project days since launch have been days where zero forward progress
has been made. (These data do not distinguish any days where Bertha was
operating, but may have made zero progress from any days where she
wasn't operating at all — any day with zero progress was counted as a
In terms of production, Bertha's rates have varied on the days she has
been digging. On the whole, she has averaged just under 22 feet a day on
days when forward progress occurred. There have been only four mining
days where she made more than 50 feet of progress and there have been 16
mining days where she eked out ten feet or less of forward progress.
Over the entire time of the tunnel drive, from launch and including all
machine downtime, Bertha's average progress is a meager six feet per
day. That's a vivid demonstration of how a low utilization rate crushes a
project's momentum and will ultimately impact the overall schedule.
WSDOT has cited a high tunneling rate of 37 feet per day, but that only
was during the four days immediately prior to Bertha's shutdown, when
the TBM was being run at fill tilt — so much so that WSDOT demanded data
from the contractor out of concern that the machine was being pushed
beyond operating limits.
To put the situation in big picture terms, a few weeks from now, Bertha will have used up half the original 14 month schedule,
but only travelled about one-tenth of the planned distance. That is a
schedule reality that will become increasingly difficult for WSDOT and
Seattle Tunnel Partners to ignore before the press, the public and