June_2022 - 16

Mid-Coast Corridor Program
to provide a link between the west
and east campuses of UC San Diego
that was to be located directly
under a viaduct for the rail project.
" There was no way [the I-5
auxiliary lane and Gilman Drive
Bridge] could be built until after
we finished the light rail. We negotiated
it and [these projects] were
brought into our program, " explained
Meisgeier. " At one point,
we had three levels of construction
going on between the light rail,
the Gilman Bridge and then at the
I-5 level. "
The supplements added complexity
to the administrative
side of construction with each
requiring its own billing, which
MCTC managed to support its
subcontractors, and each carried
different requirements for small
and disadvantaged business goals
and reporting. Weekly production
meetings and monthly cost meetings
helped keep this work in line.
Back in the planning phase,
SANDAG recognized the corridor
improvements would require an
immense amount of coordination,
which is why the CM/GC delivery
method was selected as it inherently
brings collaboration to the
design, plans and construction of
a project.
During preconstruct ion,
MCTC identified a control point
that needed to be relocated for
work in the LOSSAN corridor to
take place. The control point relocation
was part of a long-range
plan, but not part of the initial
scope of the Mid-Coast Corridor
project. MCTC worked with SANDAG
and North County Transit
District (NCTD) to accelerate plans
to relocate the control point, which
moved train traffic through the
corridor and provided space for
the Mid-Coast Corridor project
to be constructed.
MCTC also worked closely
with NCTD on the Joint Right of
Entry (JROE) permits required to
work adjacent to an active railroad.
MCTC says the process was revised
to support a large-scale construction
effort. MCTC worked with
NCTD to provide delineation for
certain work activities to proceed
uninterrupted. In addition to a refined
permitting process, MCTC
hired supplemental flaggers to help
support safe working conditions
throughout the corridor.
Working adjacent to active
tracks also required innovation
when it came to construction elements
outside of the tracks, such
as retaining walls. The original design
called for cast-in-place walls
using a soldier pile shoring system
and mechanically stabilized earth
(MSE) walls. According to MCTC,
By the
numbers
1
arched roadway
bridge over 1-5
1.4 million
cubic yards of
earthwork
500,000
square feet
of walls
2-mile
bikeway path
MCTC HANDLED
the construction
of an auxiliary
lane on I-5, built
the Gilman Drive
Bridge (middle
structure) and
the light rail
bridge (top).
" geotechnical investigations determined
that the top 15 feet of the
existing ground was full of large
cobbles and caving soils which
presented high schedule and cost
risk for soldier pile installation.
Compounding the problem was
that the railroad would not allow
MSE walls. "
The solution was a pre-cast
retaining wall system, which
eliminated the need for shoring
through the use of slot cuts where
narrow excavations were made
along the tracks without compromising
the existing embankment.
MCTC says the wall system
reduced excavation and export of
potentially contaminated materials,
allowed for rail operations to
continue uninterrupted and saved
millions of dollars and months of
the schedule.
Effective Training
As with all rail projects, safety
was paramount, and the project
concluded with an admirable
safety record. In an industry
where the average recordable
incident rate is 3.4 and the average
lost time incident rate is 1.2,
MCTC employees had a 1.28 recordable
incident rate and a 0.17
lost time incident rate based on
3.43-million manhours worked.
Subcontractors had a 1.27 recordable
incident rate and a 0.23 lost
time incident rate with 1.73-million
manhours worked.
Meisgeier notes the culture of
the project was also steeped in
safety, which began early in the
program with a third-party assessment
of the program's safety
culture and climate. MCTC says
all levels of management brought
the focus on safety to the craft level,
giving ownership and accountability
for safety to all members of the
team. Subcontractors were included
in every safety meeting and each
one was paired with an MCTC
employee who provided mentoring
and assistance, as well as performed
regular audits on safety
performance and compliance.
16 | Mass Transit | MassTransitmag.com | JUNE 2022
http://www.MassTransitmag.com
June_2022

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