how often do you cross a bridge and think to yourself this is magnificent
hi everyone my name is ken welcome to this house today we are exploring the edes bridge an early
engineering marvel that continues to impress us to this day eads bridge was built by the illinois and
st louis bridge company with the keystone bridge company founded in 1865 by andrew carnegie serving
as subcontractor for steel superstructure erection andrew carnegie led the expansion of the american
steel industry in the late 19th century and became one of the richest americans in history because of
the increased reach of newly constructed railroads river shipping trade had declined in importance
compared to the earlier years chicago was fast gaining as the center of commerce in the west the
bridge was conceived as a solution for st louis to regain eminence by connecting railroad and vehicle
transportation across the river although he had no prior experience in bridge building james eads
was chosen as chief engineer for the bridge in an attempt to secure their future steamboat interests
successfully lobbied to place restrictions on bridge construction requiring spans and heights
previously unheard of this was ostensibly to maintain sufficient operating room for
steamboats beneath the bridge's base for the then foreseeable future the unproclaimed purpose was to
require a bridge so grand and lofty that it was impossible to erect according to conventional
building techniques the steamboat parties planned to prevent any structure from being built in order
to ensure continued dependence on river traffic to sustain commerce in the region such a bridge
required a radical design solution the mississippi river strong current was almost 12 and a half feet
per second and the builders had to battle ice flows in the winter the ribbed arch had been
a known construction technique for centuries the triple span tubular metallic arch construction was
supported by two shore abutments and two mid-river piers four pairs of arches per span upper and
lower were set eight feet apart supporting an upper deck for vehicular traffic and a
lower deck for rail traffic construction involved varied and confusing design elements and pressures
state and federal charters precluded suspension or drawbridges or wooden construction there were
constraints on span size and the height above the water line the location required reconciling
differences in heights from the low illinois flood plain of the east bank of the mississippi river
to the high missouri cliff on the west bank the bedrock could only be reached by deep drilling
as it was 125 feet below water level on the illinois side and 85 feet below on the missouri
side these pressures resulted in a bridge noted as innovative for precision and accuracy of
construction and quality control this was the first use of structural alloy steel and a major
building construction through use of cast chromium steel components the completed bridge also relied
on significant and unknown amounts of wrought iron eads argued that the great compressive strength of
steel was ideal for use in the upright arch design his decision resulted from a curious combination
of chance and necessity due to the insufficient strength of alternative material choices
the particular physical difficulties of the site stimulated interesting solutions
to construction problems the deep cases used for peer and abutment construction signaled
a new chapter in civil engineering piers were sunk almost 100 feet below the river's surface
unable to construct false work to erect arches because they would obstruct river traffic eids
engineers devised a cantilevered raking system to close the arches the eats bridge was recognized as
an innovative and exciting achievement it secured 47 patents during his lifetime many of which were
taken out for parts of the bridge's structure and devices for its construction on june 14 1874 john
robinson led a test elephant on a stroll across the new eats bridge to prove that it was safe
a big crowd cheered as the elephant crossed the bridge towards the illinois side popular belief
held that elephants had instincts that would make them avoid setting foot on unsafe structures
president ulysses s grant dedicated the bridge on july 4th 1874 and general william t sherman
drove the gold spike completing the construction after completion 14 locomotives crossed the bridge
to prove its stability the bridge stood strong allowing millions of people to travel across it
over the century to come in 2012 the bsda metro started the eats bridge rehabilitation project to
extend the life of the bridge to at least the year 2091. the restorations including replacing 1.2
million pounds of struts bracing and other support steel dating to the 1880s removing all paint and
corrosion from the superstructure repainting the superstructure with a rust inhibiting coating
repairing damaged structure rebuilding concrete supports restoring the brick archways
and upgrading the metrolinx rails the total cost was 48 million dollars with 27 million dollars
coming from the american recovery and reinvestment act of 2009 while expected to start in 2009 work
did not begin until 2012 due to labor disputes and higher than expected cost estimates workers
completed the project in 2016. thank you all for watching i really hope that you enjoyed this video
i would also like to extend a special thank you to our members whose names you can see on screen
right now please make sure to like comment share and subscribe i'll see you next time on this house!