Railway bridges are subjected to dynamic loadings. Dynamic loads impart additional impact force on bridges. The deformations and stress ranges are differing on these bridges. The stress ranges depends on speed of the train, intensity of loading on the bridge and number of cycles of same loading at different speed and different loads at same speed. Hence the failure of loads happens at lesser load than that of actual ultimate load carrying capacity of bridge material. Design of bridges at higher load than the fatigue failure load becomes expensive, uneconomical and less durable. Hence it is necessary to understand the fatigue behavior of bridges to ascertain the life of existing bridge in years and to arrive at the optimized cost effective cross sections of new bridges for varying loads and speeds. Variation of remaining life of bridge with respect to loads and speed are discussed in this paper considering the structural details, loading history and material specifications of bridge. © 2015 CAFET-INNOVA TECHNICAL SOCIETY. All rights reserved.