Page 11 - May-June 2021 Vol 39 No 1
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old structure, we immediately began replacement of the existing concrete approach construction plans were
to consider not only how we could beam superstructure with a new submitted to the county on August 20,
extend the service life of the bridge, prestressed box beam superstructure. 2020, just 44 calendar days (32 business
but also how we could do so quickly,” The typical section of the bridge allows days) after receiving the notice-to-
he said. “Our bridge team was able to for two 11'-0" lanes with guardrail used proceed.
provide options to Knox County that for the barriers. The existing abutments Quick Action Leads to Sturdy Fix
demonstrated the cost of different types stayed in place, and were modified
of accelerated construction.” for the new prestressed box beam The replacement structure consists of
superstructure. a single 25-foot-long span with precast
Preparation of preliminary plans prestressed box beams and a composite
began with a survey of the bridge and The decision was made to use reinforced concrete deck slab. The
approaches. The survey revealed the prestressed box beams, while reusing the existing closed abutments have been
bridge was originally constructed as a existing substructures. The design was repaired and reutilized to support the
‘flat’ structure, meaning the abutment expediated so that the bridge could be new semi-integral superstructure.
corner and beam seat elevations were all quickly constructed and opened back up
identical, leaving the concrete deck and to the public. In late March 2021, contractor crews
curbs with no longitudinal (along the finished guardrail construction and
roadway) grade. Yarnell Road, however, Thirty-percent preliminary plans surfacing, opening the bridge. The speed
did have a longitudinal slope that was were delivered on July 15, 2020, eight of the repair work was notable, since
created completely out of asphalt overlay days after the on-site scoping meeting, the date for the notice to proceed with
on the bridge. in which several alternatives were construction had only been January
presented, including an Accelerated 4, 2021. Gresham Smith provided all
In its preliminary plans, the Gresham Bridge Construction (ABC) option to National Environmental Policy Act
Smith team made the decision to hold replace the structure in a matter of days (NEPA) and utility coordination,
the existing grade of the roadway by instead of months. The ABC option surveying, approach roadway design,
modifying the western abutment of the ultimately was eliminated because the and bridge design services.
structure, allowing the same vertical benefits to the construction schedule
alignment of the road surface without the were outweighed by the construction “In the end, we believe our approach
load and expense of an asphalt wedge. cost (and limited county funds.) provided technically sound options
Preliminary Plans Included Multiple that could be built within an expected
Options Sixty-percent design development budget in a very compressed three-
plans were submitted on Aug. 7, 2020, month schedule,” Brady said.
Preliminary plans included just one month after the on-site scoping
meeting. Final bridge and roadway
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