No, roads and railroads do nothing to your tiles apart from the faster movement on them for units. No +gold for roads. No additional production for railroads. They actually cost you maintenance (-1/-2 gold per turn per road/railroad). However you do get quite a large amount of gold per turn (unless the cities are very small) when you connect a city via roads (or railroads or harbors) to your capital (trade routes).
And you also gain a production bonus of +50% (oh yeah!) in cities that are connected to your capital via railroads. Again however, the stupid capital itself does not get that bonus. Lets call it a minor design flaw/oversight they couldn't spent a minute on yet to fix it.
Hope this reminds myself of actually trying to make another city instead of my capital my production Mecca next time (like for e.g. not building the Ironworks in the capital).
Question to all CiV veterans: If my capital is on a small island, I basically won't ever get to enjoy the railroad bonus even if I connect all other cities with each other and them to the capital with an harbor?