The hydrocarbon chemicals in the railroad ties break down over time.  It is also unlikely they would enter the plant unchanged.  My concern would be if the ties were treated with a heavy metal such as lead or arsenic, which would remain in the soil.  You could get a soil test done for lead:
https://soiltest.cfans.umn.edu/testing-services/lawn-garden

Here is a response to a similar question with a more cautious approach:
https://ask2.extension.org/kb/faq.php?id=786369