Page 265 - Challenges in Corrosion Costs Causes Consequences and Control(2015)

CORROSION CONTROL OF BRIDGES 243

1. Annual routine maintenance is the same as for the deck with corrosion.
2. No patching is required.
3. An overlay is required for improved skid resistance at 50 and 85 years (overlay
life of 35 years) giving a bridge life of 120 years.
4. Deck is removed after 120 years

The annual cost of a “corrosion-free” bridge deck amounts to $15,700. The
annual cost of corrosion for an average bridge deck is the difference between the
annual cost of corrosion ($22,000) and that of a corrosion-free deck ($15,700) or
$6300–2300 ($18,000–15,700). The total estimated cost of corrosion for bridge
decks is $2.93–$1.07 billion.
The differences in the two maintenance scenarios that resulted in the range of
corrosion-related costs were experience-based maintenance and information-based
maintenance with crack repair. This difference represents the range of maintenance
from minimal practice to best practice. The cost analysis estimated the cost of cor-
rosion from $6300 (minimal practice) to $2300 per deck per year (best practice).
These values show that a saving of 63% of the corrosion is possible by adopting the
best practice although the actual bridge maintenance is between the minimal and best
practice.
Assuming an average of the maintenance of 46% savings or $2000 per bridge per
year can be achieved by improving maintenance practice. These savings were calcu-
lated for black steel rebar decks for which improved maintenance can still provide
savings. However, corrosion of many black steel rebar decks has progressed to the
extent that improved maintenance will not make a significant difference. For these
decks, other rehabilitation options must be considered such as CP, overlays, or elec-
trochemical chloride removal. The savings of $2000 per bridge per year translates
into $0.93 billion for all the bridges per year.
The area of the substructure and superstructure (minus deck) was estimated to
be similar to the deck surface area of an average bridge. Estimation of the cost of
substructures and superstructures without deck consisted of:

1. Repair and maintenance for the substructure/superstructure cost significantly
more per surface area than the deck.
2. In nonmarine applications, the percent of surface area deteriorated because of
corrosion of reinforcing steel is much less and often is limited to area beneath
expansion joints and drains, which are exposed to deicing salt runoff.
3. Corrosion problems are hence more prevalent on substructures than decks in
severe marine environments.

On the basis of these considerations, the cost of corrosion of substructures and
superstructures without deck is estimated to be 2.93–1.07 billion dollars.
In the case of steel bridges, there is an additional cost for maintenance painting, and
expenditure for painting is estimated at $0.5 billion per year. The total annual direct
cost of corrosion of bridges: estimated to be $10.15 billion to $6.43 billion itemized as