Loads on Track, Ballast Fouling, and Life Cycle under Dynamic Loading in Railways

In this paper a new method is presented for the estimation of actions on sleepers and the pressures that develop under the seating surface of the sleeper and are transmitted on the ballast. Results from laboratory tests performed on ballast are also presented. The tests were conducted in laboratories in France, Austria, and Greece, and resulted in the formulation of an equation describing the time evolution of ballast fouling. Moreover, a new method for the calculation of the actions on the railway superstructure is analyzed and compared with observations of tie cracking on railway track. The influence of the ballast stressing on track performance as derived from the tests and theoretical analysis is also discussed. Finally the empirical equation derived from laboratory tests is extended to include a relationship between the hardness of ballast and its expected life cycle due to fouling. Its validity is verified in a case study of ballast fouling.