Assessing the Impact of Fouling on Shear Strength of Railway Ballast in Nigeria

Abstract

Ballast aggregate-supported railway tracks are essential to train operations because they offer a reliable and effective mode of transportation from point of origin to point of destination. However, fouling elements infiltrating the ballast layer significantly compromise its shear strength, thereby affecting the stability of the railway infrastructure. This research investigates the impact of fouling materials on the shear strength of ballast used in the Nigerian railway system. Laboratory experiments were conducted using clean ballast samples as a control and introducing four types of fouling materials at varying percentage levels for comparison. The shear strength of these samples was then assessed using direct shear tests. The results demonstrate that increasing fouling levels in the ballast reduces shear strength across all confining normal stress levels, with a concurrent decrease in the friction angle. These findings underscore that fouling infiltration substantially diminishes the shear strength of ballast. To mitigate this issue, railway engineers must implement proactive maintenance measures and routinely monitor the ballast bed for fouling infiltration to preserve track stability and performance.