RAIL DISTORTION. EFFECTS ON TRACK STRESS, TRACK BED STABILITY AND THE INCIDENCE OF OPERATING TROUBLE

The cushioning effect of the rail which is important for the wheel-sets to ride smoothly depends largely on the type of ballast used to support the track panel. If the sub-soil is rocky, or on bridges and in tunnels, it is therefore necessary to incorporate a kind of mattress underneath the ballast, which also avoids overstressing the ballast itself. A high density material must be used to support the track panel, which also has the effect of increasing safety, particularly with regard to lateral buckling of the track. When the track is surveyed (rails and sleepers), a minimum safety factor of 99.7 percent must be applied.