Nondestructive and Destructive Testing of Wood Railroad Ties

Abstract Nondestructive evaluation of wood railroad ties was previously investigated using acoustic velocity (AV). Flexural properties, however, have not been well studied among legacy ties as well as new ties of wood species and grades. Therefore, modulus of elasticity (MOE) and modulus of rupture (MOR) from two groups of wood species for three grade conditions were investigated. For similar ties, regression analysis of destructive and nondestructive data was performed. Overall, 60 new on-grade, 40 new off-grade, and 55 Grade 1 legacy ties were examined. The wood species groups were either oak/hickory or mixed hardwood. MOE and MOR of destructive evaluation were obtained, and these were compared with their companion AV value of each tie using polynomial regression analysis. All destructive evaluation data were analyzed using two-way analysis of variance. There was a statistically significant interaction between species and grade for MOR ( P < 0.0010), in which new, on-grade oak/hickory ties had a higher MOR compared with mixed wood. Furthermore, a higher MOE ( P < 0.0001) was observed for oak/hickory than for mixed wood ties. Additionally, the highest MOE ( P < 0.0132) belonged to new on-grade ties, whereas legacy ties had the lowest MOE. A significant relationship was observed between AV free and fixed and with MOE and MOR. These results indicate that both wood species and grade conditions are important factors for determination of strength and stiffness of ties. Additionally, AV could be useful technology for grading new ties and for identifying legacy ties that should be removed from service.