The main benefit of prestressing is that the build up of tension under service loads and possible cracking may be avoided or reduced to a low level. The effective stiffness of the cross-section is increased, leading to a reduction in deflections. This is particularly important for long-span structures and results in lower overall depths. Deflected tendons can enhance the shear capacity of sections, with the vertical component of the prestressing force carrying a proportion of the load. Prestressing should enhance the fatigue resistance of structures subjected to repeated loads, such as bridges. Finally, prestressing is beneficial in many forms of segmental construction; placing the interface between units into compression and enhancing the load transfer capacity.