Yeah, they correlate.
I have divvied it into 4 eras for rail.
beginning to 1835. Early days
Limited selection. Everything is cheapish, light and slow. Slow, but still faster than other ways after 1828.
1835 to 1885. Expansion
This is where engineering really kicks off and you get a plentiful selection of bridges. Not that many tracks, since everything is still light, but as an added bonus, some short months of cheap, subsidized rail. Caution should be taken to not over expand the network, because maintenance is still the same.
1885 to 1950. Heavy weights
Faster and heavier trains call for some heavy gauge track and bridges to match. May be hazardous to wallet if you don't pay attention to what you are buying for your needs.
1950 onward. End game
Mostly, the only change is cost and speed when compared to heavy weight era. Still, it should be possible to start up new companies with rail. Concrete and Steel become the staple food, however wood still looks favourable in some situations.