Page 56 - Bridge and Highway Structure Rehabilitation and Repair

CHAPTER 1 OVERVIEW OF BRIDGE ENGINEERING 31

• Shutting down will result in unacceptable delay and detour.
• There is too much local opposition to shutting down.
These alternatives must be carefully considered as to their practicality, overall cost, delay

of traffic, and impact to the surrounding community. In some cases, the type of bridge work
will be driven by the fact that there is only one practical solution to managing the traffi c.
7. Use of a temporary bridge during construction: Examples are the portable Bailey bridge as
successfully used by military engineers and the Mabey panel bridge.

1.10 SUCCESS OF WELL-MAINTAINED STRUCTURES

1.10.1 An Historical Perspective
1. Civil engineering structures are indispensable to a civilized society. So great is the importance
of structures that in recognition, modern marvels are displayed in pictures and on postcards.
They include the Pyramids, the Roman Coliseum, The Taj Mahal, the Great Wall of China,
and many other landmarks such as the Empire State Building, Leaning Tower of Pisa, and
Sydney Opera House.
2. Romans were the first great bridge builders. Their stone arch bridges are still in use today.

Other building materials used were timber, masonry, cast iron, wrought iron, and steel.
London’s Tower Bridge, Venice’s Rialto Bridge, and Prague’s Charles Bridge are well known
examples. It appears that the use of weaker materials had restricted their use in the past.
Historic bridges however show ingenuity and the future of the industry is bright. Much
stronger building materials such as composites and HPS 100W are on the horizon.
3. Structural engineering serves the community needs and the bridge is an important part of
structural engineering infrastructure. It displays and demonstrates the wisdom of sages.

Every structure, renowned or not, seems to provide immense benefit to society.
4. Bridge engineering facilitates transportation and is an industry in itself. It is rated high as
a scientifi c profession in terms of benefi ts and level of complexity. It is made up of many

trades, including land development, excavation, fill, drainage, pile driving, sub-surface and
overhead utility pipes, masonry, cast-in-place and precast concrete components, steel rein-

forcing bars, carpentry, metal work, welding, deck overlay, traffic signs, lighting, macadam
surface, and railroad construction.
5. More recent examples in the Americas of structures using similar construction technology
as that used for bridges include the Hoover, Boulder, and Grand Coulee dams, sky scrapers,
nuclear power plants, and the Panama and Eerie canals.

1.10.2 The Golden Age of Bridge Building Between the First and Second World Wars
1. Well known examples are:
• The George Washington, 1931
• The longest steel arch Bayonne, 1931
• Sydney Harbor, 1932
• Tri-borough, 1936
• Golden Gate, 1937
• Blue Water Bridge linking Michigan with Ontario, 1938
• Tacoma Narrows Bridge (which collapsed in November 1940): Details of failure under
wind are given in Chapter 3.
2. Suspension bridges fell out of favor in Europe in the 19th Century because they were vul-
nerable to wind. American bridge builder John Roebling studied the failure of these bridges
and determined that adding more weight, guides, trusses, and stays to suspension bridges