Civil Engineering Reference
In-Depth Information
occurring simultaneously in the United States and England following the British
industrial revolution.
In the United States, there was an intense race among emerging railroad companies
to expand west. Crossing the Mississippi River became the greatest challenge to
railroad growth. The first railway bridge across the Mississippi River was completed
in 1856 by the Chicago, Rock Island, and Pacific Railroad.
∗
The efforts of the B&O
Railroad company to expand its business and cross the Mississippi River at St. Louis,
Missouri, commencing in 1839
†
and finally realized in 1874, proved to be a milestone
in steel railway bridge design and construction. Although the St. Louis Bridge never
served the volume of railway traffic anticipated in 1869 at the start of construction,
its engineering involved many innovations that provided the foundation for long-span
railway bridge design for many years following its completion in 1874.
The need for longer and stronger railway bridges precipitated a materials evolution
from wood and masonry to cast and wrought iron, and eventually to steel. Many
advances and innovations in construction technology and engineering mechanics can
also be attributed to the development of the railroads and their need for more robust
bridges of greater span.
1.2 IRON RAILWAY BRIDGES
1.2.1 C
AST
I
RON
C
ONSTRUCTION
A large demand for railway bridges was generated as railroads in England and
the United States prospered and expanded. Masonry and timber were the principal
materials of early railway bridge construction, but new materials were required to
span the greater distances and carry the heavier loads associated with railroad expan-
sion. Cast iron had been used in 1779 for the construction of the first metal bridge, a
100 ft arch span over the Severn River at Coalbrookedale, England. The first bridge
to use cast iron in the United States was the 80 ft arch, built in 1839, at Brownsville,
Pennsylvania. Cast iron arches were also some of the first metal railway bridges
constructed and their use expanded with the rapidly developing railroad industry.
‡
Table 1.1
indicates some notable cast iron arch railway bridges constructed between
1847 and 1861.
The oldest cast iron railway bridge in existence is the 47 ft trough girder at Merthyr
Tydfil in South Wales. It was built in 1793 to carry an industrial rail tram. The first
iron railway bridge for use by the general public on a chartered railroad was built
in 1823 by George Stephenson on the Stockton to Darlington Railway
(Figure 1.1).
∗
The bridge was constructed by the Rock Island Bridge Company after U.S. railroads received approval
to construct bridges across navigable waterways. The landmark Supreme Court case that enabled the
bridge construction also provided national exposure to the Rock Island Bridge Company solicitor,
Abraham Lincoln.
†
In 1849, Charles Ellet, who designed the ill-fated suspension bridge at Wheeling, West Virginia, was
the first engineer to develop preliminary plans for a railway suspension bridge to cross the Mississippi
at St. Louis. Costs were considered prohibitive, as were subsequent suspension bridge proposals by
J.A. Roebling, and the project never commenced.
‡
Cast iron bridge connections were made with bolts because the brittle cast iron would crack under
pressures exerted by rivets as they shrank from cooling.
