Historically, the D&RG used cinder under its ties.
There are curves now where the track will slide on the wet gumbo with the pull of the train and if the train went into emergency brake application for some reason at that specific spot, you might slide it off the right-of-way and cause a spill. A surface job with any new material under the tie will solve that threat.
Also, Remember my suggestion several months ago that all the train crewmen hit the ground at every emergency stop to inspect all the wheels. And the train is not started until the conductor singals the start and also gives a second okay one car length futher to confirm all the wheels and track are okay. The rule book needs a change for added safety. Most mega-railroad require a track foreman to be called to inspect the site of any emergency stop for track damage.