The overall economy of a structure is measured in terms of its life cycle costs.
This includes the initial cost of the structure plus the maintenance cost. Prestressed
concrete bridges do well in both these aspects.
Low initial costs
Prestressed concrete bridges are economical as well as provide for minimum downtime
for construction. Carefully planned details speed the total construction process
and result in overall economy.
Minimal maintenance
Of course no painting is needed. Some engineers believe that this alone adds about
10 to 20 percent of the initial costs of a steel bridge over the period of its useful
life.
Prestressed concrete structures, built in the late 1950s, have now withstood heavy
traffic and severe weathering for nearly 50 years and yet require practically no
maintenance. Simpler and more reliable bearings require no maintenance.
Durable
Because of the high quality of materials used, prestressed concrete members are
particularly durable. Fatigue problems are minimal because of minor stresses induced
by traffic loads. High strength prestressed concrete has excellent freeze-thaw and
chloride resistance, as demonstrated by the performance of prestressed concrete
girders.
Fire resistance
Prestressed concrete bridges are not easily damaged by fire. Fires hot enough to
consume metal bridge rails require only cosmetic repairs to restore a prestressed
concrete bridge to its original condition.