There are still some traditional railroad ties along the routes Basil and I most frequently ride.
As this image illustrates all too well, though, aged wood appears to degrade over time. Tons of train passing over constantly probably accelerate the process considerably.
Cement seems to be the contemporary tie of choice:
I wonder what the longevity is for these. Cement is theoretically stronger stuff, but it’s not impervious to cold, and it’s often not sturdy when flexed.
Daily movement, of course, between the rails and ties, is accommodated by these attachments, which are almost delicate
especially compared to the traditional ones
which have broad plates attached with large spikes hammered into the wooden ties.
Both attachment methods allow the ties to “float” a bit; all that vibration from rolling trains needs to run out safely. That’s the same theory that demands that buildings flex in earthquake country: A building that flexes when the earth moves has the best chance of remaining intact. Ditto, I assume, for ties attached to vibrating steel rails.