Switch failures are the #1 cause of train delays on all railroads. Approximately 90% of these failures are due to the switch point circuit controller indicating that the switch point is “out of correspondence” or “gapped”.
What causes this? “Running rail” is the primary culprit and is caused by the expansion and contraction of the switch points due to thermal variation as well as everyday train traffic. This causes the point detection rod to pull or push on the ICC and indicate “out of correspondence” thus stopping train traffic.
Another contributing factor to the switch failures is the switch rods or basket becoming lodged on the ties when it is jammed against it from the expansion and contraction of the points. This results in damaged ties, insulation and spring/center baskets. This also contributes to internal switch machine damage and excessive force needed to throw the switch.