Key Findings

• Recent testing agreed with past observations that concrete ties may be more prone to center cracking in track affected by mud pumping. If the suboptimal support conditions are fixed, the bending values will return to a more desirable range. This finding likely also extends to other sources of suboptimal support conditions, such as poor subgrade.
• Concrete tie bending was strongly related to support conditions and vertical wheel loads. Moderately cracked ties did not appear to have any influence on tie bending on the cracked ties themselves or on adjacent ties.
• The testing further supports the likelihood that the majority of concrete ties (assumed to have good support conditions) will remain unaffected by center cracking, allowing the ties to be in service longer than the marketed 40-year tie life, as long as the ties avoid another failure mode. Concrete ties that have center cracked under suboptimal support conditions are still anticipated to have useful life remaining, the duration of which likely depends on support conditions and weathering (e.g., rainfall, freeze/thaw cycles, and drainage), as well as traffic conditions and other factors.