Metra Rock Island
District 24 Bridges and Retaining Walls from 18th to 60th Street
Client: Metra
Location: Cook County, Illinois
Construction Completed: 2005
Construction Cost: $87 Million
Challenge
Bowman, Barrett & Associates Inc. (BB&A) led a multi-firm
team to replace for 24 bridges, retaining walls and track between
18th and 60th Streets on Metra’s Rock Island District. The
new bridges and walls replace structures constructed in the 1890’s.
The existing bridges are very similar to each other, typically
six-bay and three-span bridges, with 66 feet between abutments
with few exceptions. The new structures meet Metra’s current
capacity requirements and the City of Chicago’s vertical
clearance requirements, as well as enable an alignment that allows
higher operating speeds.
Details
Metra wanted to continue to provide reliable rail service throughout
the construction period, so BB&A developed a detailed staging
plan. Most of the construction took place off to the side of
active tracks. Construction that had to disrupt service, such
as tying in to the new track, was scheduled in time slots between
trains. The result was no disruption of the Metra schedule.
The new bridges will be two-girder through-plate girder spans
of a higher capacity than the existing bridges. A consequence
of replacing the spans is that the roadway vertical clearances
will be improved to meet the Chicago minimum requirements. The
retaining walls on the east side of the right-of-way will also
be replaced as part of this project. The railroad’s profile
and alignment will be improved as a consequence of the bridge
replacements, resulting in a faster, safer railroad.
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