Brief question on Railroads

[onomastikon]

Hello, newbie here, I am confused about Railroads (RR). Many of my workers on continent X connected to Coal resources have the RR icon in their list of actions they can perform, but other workers on the same continent, sometimes in the same city area, cannot build RRs. What is the deal? Is there a secret condition for building RRs that is not listed in the Civoped or manual? This is vanilla Civ3 1.29f.
Thanks!

 

[HellboundHeathcliff]

The tile needs to be connected to the trade network via a road already.

 

[onomastikon]

Oh well that makes sense, I wonder if that was the case...? So to make it absolutely clear: You can *only* build RRs over tiles with roads? Thank you.

 

[HellboundHeathcliff]

over tiles with roads that are connected to iron and coal.

 

[gmaharriet]

I know you already said everyone was on the same continent, but if you should expand to an island or another continent, you'll need a harbor to import the iron and coal to build RR there.