Civil Engineering Reference
In-Depth Information
FIGURE 1.12
The St. Louis (Eads) Bridge built across the Mississippi River in 1874 at
St. Louis, MO. (Historic American Engineering Record.)
for longer spans and their use of increasingly heavier locomotives and freight cars
caused Andrew Carnegie
∗
and others to invest considerable resources toward the
development of improved steels of higher strength and ductility. The first exclusively
steel railway bridge (comprisingWhipple trusses) was built by the Chicago andAlton
Railway in 1879 at Glasgow, Missouri.
Despite concerns about suspension bridge flexibility under train and wind loads,
some American bridge engineers continued to design and construct steel suspension
railway bridges. The famous Brooklyn Bridge, when completed in 1883, carried
two railway lines. However, lingering concerns with suspension bridge performance
and increasing locomotive weights precipitated the general demise of this relatively
flexible type of railway bridge construction.
The structural and construction efficacy of cantilever-type bridges for carrying
heavy train loads led to the erection of many long-span steel railway bridges of
trussed cantilever design after 1876. The Cincinnati Southern Railway constructed
the first cantilever, or Gerber
†
type, steel truss railway bridge in the United States
over the Kentucky River in 1877.
‡
In 1883 the Michigan Central and Canada South
Railwaycompletedtheconstructionofacounterbalancedcantileverdecktrussbridge
§
∗
Andrew Carnegie worked for the Pennsylvania Railroad prior to starting the Keystone Bridge Company
(with J.H. Linville) and eventually going into the steelmaking business.
†
This type of bridge design and construction is attributed to the German engineer Heinrich Gerber who
patented and constructed the first cantilever-type bridge in 1867.
‡
At the location of an uncompleted suspension bridge by John Roebling.
§
This was the first use of cantilever construction using a suspended span.
