Field studies on sleeper deflection and ballast pressure in heavy haul track

Deflection of sleepers (vertical displacement) and ballast pressure (vertical stress) under traffic loads are two important performance indicators for determination of rail track quality. Excessive values of these parameters can adversely affect the track structural stability, accelerate the track deterioration and consequently affect the safety of running trains. This paper reports field tests on two heavy haul tracks in Australia with normal operating condition and similar traffic loads. In the first test site, the ballast pressure and sleeper deflection were measured. In the second site, only the sleeper deflections were recorded; however, in this site, the capping layer interface was modified using inserts of various design of geogrids. Analysis of results obtained from these field measurements provide valuable insights into the sleeper deflection and ballast pressure magnitudes and patterns under real life traffic in heavy haul tracks as well as the effects of geogrids on reducing the sleeper deflections.