Simply supported multi-span deck required an expansion joint above each support(pier) to maintain the separation between deck spans so it will work as a simply supported deck. the number of the expansion joint and bridge bearings in simply supported multi-span deck is significantly greater compared to continuous multi-span deck.
Adopting continuous deck over simply supported deck for bridge construction will contribute to the reduction of construction and maintenance cost by reducing numbers of expansion joints and bearings. besides reduction in cost, it will reduce the inconvenience of road commuter resulted from road closure for maintenance. Choosing continuous deck over a simply supported deck. will contribute to reducing deck depth through deck sucker principle. reduction of depth will reduce the dead-load of superstructure and this will be followed by a reduction of pier and foundation size.
This will play an important part in reducing the cost of construction and producing economical design. However, some designer preferred to add more expansion joints to guard against the possible occurrence of differential settlements.