Actually, lifespan of precast decks is higher than of CIP. CIP decks are notorious of transverse cracking due to concrete shrinkage. Crack-free post-tensioned concrete, reduced shrinkage, plus overlay provide better product that cost 50% more than CIP deck. In our case we provided alternative bids for CIP and precast deck, so the client will be able to choose between money and durability. Majority of precast decks in the US have been built as deck replacements rather than on new bridges.
Precast deck may become more economical for tall bridges over the water, when access from underneath is limited, and panels placed consequently starting from abutments into the span. Also on-site construction time for precast is shorter.
Compare costs:
CIP deck $500 to $700 per cubic yard
Precast deck $25 to $30 per square foot (9" thick yields to $900 to $1080 per cubuc yard) + installation (high strength grout, post-tensioning...)
But if the client wants it we deliver!