Design and Construction of Modern Steel Railway Bridges

The need for reliable transportation systems evolved with the ndustrial revolution. By the early 19th

century, it was necessary to transport materials, finished goods, and people over greater distances

in shorter times. These societal requirements, in conjunction with the development of steam power,*

heralded the birth of the railroad. The steam locomotive with a trailing train of passenger or freight

cars on iron rails became the principal means of transportation. Accordingly, as transportation

improvements were required, the railroad industry became the primary catalyst in the evolution of

materials and engineering mechanics in the latter half of the 19th century.

The railroad revolutionized the 19th century. Railroad transportation commenced in the UK on

the Stockton to Darlington Railway in 1823 and on the Liverpool and Manchester Railway in 1830.

The first commercial railroad in the United States was the Baltimore and Ohio (B&O) Railroad,

which was chartered in 1827.

Construction of the associated railroad infrastructure required that a great many wood, masonry,

and metal bridges be built. Bridges were required for live loads that had not been previously encoun-

tered by bridge builders.† The first railroad bridge in the United States was a wooden arch-stiffened

truss built by the B&O in 1830. Rapid railroad expansion‡ and increasing locomotive weights, par-

ticularly in the United States following the Civil War, provoked a strong demand for longer and

stronger railway bridges. In response, many metal girder, arch, truss, and suspension bridges were

built to accommodate railroad expansion, which was occurring simultaneously in the United States

and the UK following the British industrial revolution.

In the United States, there was intense competition among emerging railroad companies to

expand west. Nevertheless, crossing the Mississippi River was the greatest challenge to planned

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 to cross the Mississippi River at St. Louis, MO, 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 the 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 an evolution of materials from

wood and masonry to cast and wrought iron, and eventually to steel. Many advances and innova-

tions in engineering mechanics and construction technology can also be attributed to the develop-

ment of the railroads and their need for more robust bridges of greater span.

1.2 IRON RAILWAY BRIDGES

1.2.1 Cast Iron Construction

A large demand for railway bridges was generated as railroads in the UK 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 expansion. Cast iron had been used in 1779 for the construction of

the first metal bridge, a 30.5m (100ft) arch span over the Severn River at Coalbrookdale, UK.

The first bridge to use cast iron in the United States was the 24.5m (80ft) arch, built in 1839, at

Brownsville, PA. Cast iron arches* were 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 14m (47 ft) trough girder at Merthyr Tydfil

in South Wales, which 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 consisted of 3.8m (12.5ft) long lenticular

spans† in a trestle arrangement. This early trestle was a precursor to the many trestles that would

be constructed by railroads to enable almost level crossings of wide and/or deep valleys. Table 1.2

summarizes some notable cast iron railway trestles constructed between 1823 and 1860.

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