Ayres Associates vice president and project manager for the early
phases of the project, explained that before the H-pile and bridge
installations, extensive utility identification and relocation was
required for gas, fiber optic, and phone lines, as well as water and
storm sewer lines from the University and the City.
Clearing a 10- by 12-foot underground passageway some 6 to 12
feet under the ground while negotiating multiple utilities was, in fact,
the case for the entire project corridor, which included crossing not
only two of Madison’s busiest roadways but also some of the oldest
underground utilities in the city.
According to Klingbeil, an engineer with nearly 35 years of
municipal experience, the East Campus work was “by far the most
challenging engineering project” he’s ever worked on. “We literally
designed this 1 foot at a time to find an opening for the tunnel. If you
couldn’t find an opening, you then had to figure out how to get the
utilities out of the way,” Klingbeil said.
This was often a process of “creatively connecting the dots,” said
Anderson, who served as the Ayres Associates project manager for the
latter phases of the project. Gravity-based systems such as sanitary
and storm sewers were particularly challenging because of the need to
stay consistent with the existing grades of the project area, she said.
“Moving these sewers out of the way of the tunnel sometimes
required changing flow patterns,” Anderson said. “We rerouted sewers
to different manholes or had pipe laid in the opposite direction to a
location where we could cross the tunnel, then back along the other
side of the tunnel for reconnection to a new manhole.”
Opening up the ground at the University revealed other
challenges. “We used all the data we could gather ahead of time from
the UW and the City, but we worked with the assumption that there
would be surprises,” Anderson said. So what happened when the
project team encountered incorrectly marked or unmarked utilities
or, as she described it, 100-year-old utilities that virtually crumbled
when exposed to air? “Engineering on the fly,” Anderson said. “The
backhoe was running and that costs money. We had to process the
new data and make good decisions quickly.”
The project stayed on schedule and also allowed the surrounding
construction projects – about a dozen of them – to go uninterrupted,
keeping various construction stakeholders satisfied. More importantly,
according to the project team, the construction plan stayed true to its
focus of minimizing the effects on students and businesses in the area.
Imitation may be the sincerest form of flattery, but in the case of
this project, it’s also an indicator of success. The project may serve
as a model example for other state work involving walkable utility
tunnels and underground utilities.
Meanwhile, hidden from public view, the tunnel is functioning
as intended. Above it now lays an expansive pedestrian mall that will
surely receive its share of wear and tear in the years to come – but not
from a backhoe.
Top: A section of the mall running past a 12-story mixed used tower of rental
apartments and retail spaces. Bottom: Aerial view of a portion of the mall.
TRENDS
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