Page 418 - Challenges in Corrosion Costs Causes Consequences and Control(2015)

396 CONSEQUENCES OF CORROSION

in 1826, was reconstructed in 1938–1940 to meet the increased traffic demands, and
this was the first large bridge to be metal sprayed in the United Kingdom. This serves
as a good example of the benefits of protective coating in hostile environments.
In the past, designers applied age-old principles born out of sound engineering
practice. The results were beneficial and the structures lasted a longer time without
any problems. In today’s society, restrictions such as financial and highly competitive
tenders have paved the way to use the most advanced and often untried engineer-
ing techniques to save money. Operating margins have been trimmed to such a fine
extent that whenever a problem arises, as in a novel situation, severe penalties ensue.
Thus, the advantages of modern engineering design seem to have created a plethora
of problems that underpin the conclusions of Hoar (54).
Some examples that highlight the conclusions of the Hoar Report are as
follows.

Example 5.4 In the United Kingdom, the innovative suspension bridge over the
River Severn was heralded in 1966. In 1978, broken wires within the raked steel hang-
ers were revealed by cracking in the paintwork. The steel deck assumed an innovative
design in which aerodynamic closed box sections intended to eliminate marine atmo-
sphere from inside the boxes was implemented. In a short time, cracking of the steel
box-welds had occurred, and by 1983, concern was expressed over the future of the
link between England and South Wales. The problem was attributed to unexpectedly
high traffic loading, aggravated by corrosion because of the salt-laden atmosphere of
the Severn Estuary. The cost of repair in 1983 was £30 million. A new bridge was
eventually constructed.

Corrosion problems were experienced with the 350-m long Pelham Bridge in Lin-
coln. The bridge was constructed in 1957 when the problem because of deicing salts
was not envisaged. Penetration of the deicing salt caused severe corrosion of the steel
reinforcement in the concrete road bridge decks. Many such cases were reported in
England. The cost of repairing was considered to be high.
A report from the New York Department of Transport revealed that 95% of all
bridges in New York would be deficient if maintenance remained at the same level
as in 1981. This degree of deterioration is attributed to the use of de-icer salts. In the
snow belt of the United States, the use of de-icing salts rose from 0.6 million ton in
1950 to 10.5 million ton in 1988. The motor car damage was estimated at $5 billion.
On December 15, 1967, Point Pleasant Bridge in Ohio collapsed, killing 46 people.
The cause of the disaster was a stress corrosion crack 2.5 mm deep in the head of an
eyebar. The metal had low resistance to fracture once a notch had been initiated.
Failure led to the collapse of the bridge.
The bridge at the Charing Cross Railway in central London was subject to corro-
sion from dog’s urine. Repeated urination by dogs caused crevice corrosion in a part
of the structure that was not easily accessible. In 1979, the City of Westminster, Lon-
don, reported a problem of falling lamp posts. The culprits were dogs that urinated at
the base of the lamp posts.