Page 372 - Corrosion Engineering Principles and Practice

340 C h a p t e r 9 A t m o s p h e r i c C o r r o s i o n 341

9.3.4 Deicing Salts
Snow fighting has a long history. The first use of salt for deicing roads
can be traced back to the 1930s. However it was not until the 1960s that
the use of salt in conjunction with plowing became widespread after
winter maintenance personnel learned its effectiveness. Figure 9.11
presents the usage of deicing salt or rock salt (mostly sodium chloride)
in the United States between 1940 and 2005 (Data from the Salt Institute
www.saltinstitute.org). Initially confined to the “snowbelt,” ice fighting
has become a priority activity in the “sunbelt” too.
The Benefits of Salting
There is a vast international experience in effective snow fighting and
the efficient use of deicing salts. A 1972 study by Paul J. Claffey presented
to the Highway Research Board (now Transportation Research Board)
concluded that the roughness of road ice and slippage of wheels can
result in an increase in fuel consumption around 35 percent in averages
and as much as 50 percent when there is 5 cm of snow on the road. A
1976 report by the Institute for Safety Analysis (TISA) listed the following
cost benefits (reported here using 1976 prices and rates) of using salt in
the United States to deice highways:
• Reduces wages lost due to lateness to work by $7.6 billion
• Saves $3 billion in wage loss because of absenteeism
• Reduces production losses by $7 billion

20000

15000
(1000 tons) 10000

5000

0
1940 1944 1948 1952 1956 1960 1964 1968 1972 1976 1980 1984 1988 1992 1996 2000 2004

Year
FIGURE 9.11 Usage of rock salt for deicing in the United States in thousands
of tons.