Does anyone know when ballasted bridge decks first appeared?
Well, it's just a wild guess, but likely not long after the invention of the steam locomotive.
This one goes back a way...
...but there are older ones elsewhere in the world.
Wayne
Yes an arch or viaduct sort of bridge would or could have ballasted track and such bridges go pretty much back to the whole notion of flanged wheels on rails.
But I suspect the OP was asking about fabricated bridge floors that would contain or hold the ballast in a sort of tray of concrete or wood, or contain the ballast between steel side girders. Paul Mallory has an entire chapter in his classic book "Bridge & Trestle Handbook." He writes that ballasted bridge floors were better for high speed operation "Thus modern main lines, even some built before the turn of the century, [he was writing that in 1958] tend to use ballasted rather than open floors. This trough may be an integral part of a concrete beam bridge or one constructed on a steel or timber bridge. Such troughs may be of concrete, timber or steel."
So it seems high speed track may have involved ballasted decks before 1900, but Mallory's use of the phrase "even some built before" makes me assume they became truly common after 1900.
Dave Nelson
dknelsonThis trough may be an integral part of a concrete beam bridge or one constructed on a steel or timber bridge. Such troughs may be of concrete, timber or steel."
Certainly by 1906:
Ballast_Bridge by Edmund, on Flickr
Good Luck, Ed