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16th Avenue Railroad Bridge Rehabilitation
City of Nampa, Idaho
OVERVIEW
In 1968, a steel bridge was constructed over the Union Pacific Railroad
on 16th Avenue in Nampa. The bridge has eleven spans with a main
span of 112 feet over the railroad main line tracks. The roadway
over the bridge is a four lane undivided road. The bridge substructure
had reached a state of deterioration that necessitated repair or
replacement.
CHALLENGE
The bridge carries traffic on 16th Avenue in Nampa over one of the
few railroad grade separation structures in the City. The route has
a high traffic volume due to access from 16th Avenue to Interstate
84. Some of the piers and girder seats were highly deteriorated.
Most of the work on the bridge piers was located near the active
railroad tracks, which required the contractor to schedule his work
around the passage of train traffic and comply with railroad safety
requirements.
SOLUTION
An evaluation of the bridge condition was undertaken to determine
if the bridge should be repaired or replaced. The conclusion was
reached to rehabilitate the bridge, since it was more economical
long-term. The first phase concentrated on the substructure portion.
A later phase will complete much needed repair to the concrete deck.
The best approach to the rehabilitation work was formulated and
presented to the City and then Keller Associates proceeded with
preparing detailed plans and specifications. The work included
rehabilitation of the deteriorated concrete piers, repair of the
girder seats, and installation of an anticorrosion system to protect
the steel. The planned repair work required jacking the steel girders
that support the deck in the main spans to repair the girder seats.
The girders had to be jacked in sequence so half of the bridge
could be open to traffic at all times. The rehabilitation project
has added many years of service life to the 16th Avenue Railroad
Bridge and the City was very pleased with the project and its contribution
to the vitality of the City.
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