Quantifying bending moments in rail-transit concrete sleepers

With use of concrete sleepers increasing for rail-transit applications in the United States, it is becoming more critical to quantify their revenue service flexural demands to improve sleeper design and maintenance practices. Rail-transit concrete sleeper bending moment field data were collected and processed to address topic areas relating to (1) overall field bending moment magnitude relative to design moments; (2) moment variation from sleeper to sleeper resulting from support conditions; and (3) seasonal variations in moments. Data from field locations on light and heavy rail-transit properties show levels of reserve flexural capacity (factors of safety) that reach as high as 6, significant sleeper-to-sleeper variability attributable to support conditions that can be as high as 100%, and seasonal variation in bending moments that is measurable but far lower than daily variability caused by temperature by a factor of 2. These data provide a valuable baseline for the future generation of mechanistic design standards for track infrastructure components.