Integrity and Capacity of Melton Viaduct

Melton viaduct, a wrought iron, lattice girder railway bridge, has been in service for 98 years. It has developed buckles in some of the bottom chords which theoretically should be in tension. A detailed review of the structure with field measurements revealed that compression developed through seizure of the expansion joints and restraint of the trestles coupled with temperature and live load effects, and also through the effect of the trestle tension bracing. It has been established that the buckles do not affect structural integrity. An estimate of stress history combined with the measured stresses and laboratory tests of the fatigue life of a wrought iron splice established a virtually unlimited fatigue life. With regular inspection the structure can remain in unrestricted service for the foreseeable future.