The bridge, as a complete structural system and its structural elements should perform their functions adequately and safely, with appropriate degrees of reliability during design life and during construction. It should withstand all actions, consisting of applied and induced loads as well as environmental influences liable to occur, retaining its structural integrity, and also withstand accidental loads (e.g. barge impact/vehicular impact) and earthquake loads without causing damage, which is disproportionate to the causative event Adequacy of performance is defined in terms of serviceability, safety, durability and economy. The term degree of reliability is used to indicate the acceptably low level of probability of failure in meeting the expected performance during a specified period of time.

Bridge design methods are different in different parts of the world. While many codes are currently dealing with limit state method, South Asian countries like India, Ne¬pal etc are new to this design practice. IRC has published new code IRC 112:2011 combining specifications for both RCC and prestress concrete bridges