Document Type : Original Article
Department of Railway Engineering and Transportation Planning, Faculty of Civil and Transportation Engineering, Isfahan University, Isfahan, Iran
Department of Mechanical Engineering, Faculty of Technical and Engineering, Isfahan University, Isfahan, Iran
The nature of the vertical forces acting on the railway is dynamic due to the transitive nature of the forces and the existence of faults and failures in both railroads and railway vehicles. Considering these dynamic effects and determining the exact values of the forces on the railroad requires spending a lot of time. Hence, vertical forces are applied to the railroad as quasi-static one for design purposes. In this way, the static force of the wheel of railway vehicles (which is obtained by dividing the total weight of the railway vehicle by the number of wheels) is multiplied by an increasing coefficient known as the dynamic impact factor and the result is used in calculations as quasi-static force of the wheel in which dynamic effects are taken into account. In order to calculate the dynamic impact factor, various relationships have been presented by different institutions and researchers in the rail transport industry area. In present paper, those relationships proposed for the dynamic impact factor in which only effect of the velocity of the railway vehicle plays a role in determining their values have been studied. By examining these relationships and drawing their graphs, it was found that a) Talbot’s relation recommends more conservative values for the dynamic impact factor at velocities over 44 km/h and b) compared to other relationships, Mir Mohammad Sadeghi’s relation suggests the lowest values for the dynamic impact factor at velocities greater than 84 km/h.