Early on the Romans and Incas and Others built great stone roads which are still in use today and are of superior quality to dirt roads, then were also gravel roads, and finally what we have today with asphalt. Stone roads would take a long time to build and would require that a dirt road already be in place before you can upgrade it to stone. I think that stone roads should be available with the technology "construction", or maybe only industrious civs can build them (ie: Romans, Incas, Chinese, etc.)?
A dirt road consumes 1/3 movement point. How about stone roads, which are superior because they do not have potholes and do not turn to mud or have overgrowth, take only 1/5th movement point? Asphalt roads would perhaps be even better still, and would represent the superhighways of the modern era. Asphalt roads could perhaps consume a mere 1/10 movement point. We can do something different with railroads, too, like maybe make them cost some movement points, but not very much. Say 1/15th or 1/20th of a movement point to move on a railroad?
To summarize:
Dirt road - 1/3 movement point
Stone/Gravel Road - 1/5th movement point
Asphalt Road - 1/10th movement point
Railroad - ???
Stone roads may require access to mountains to build, from which to quarry the stones. Asphalt roads would require access to oil and if the supply of oil is severed then the roads should be reduced in effectiveness. With Railroads you need coal and steel to build but you need a constant supply of coal to maintain. If you run out then the railroads should become utterly useless.
Just some thoughts...
A dirt road consumes 1/3 movement point. How about stone roads, which are superior because they do not have potholes and do not turn to mud or have overgrowth, take only 1/5th movement point? Asphalt roads would perhaps be even better still, and would represent the superhighways of the modern era. Asphalt roads could perhaps consume a mere 1/10 movement point. We can do something different with railroads, too, like maybe make them cost some movement points, but not very much. Say 1/15th or 1/20th of a movement point to move on a railroad?
To summarize:
Dirt road - 1/3 movement point
Stone/Gravel Road - 1/5th movement point
Asphalt Road - 1/10th movement point
Railroad - ???
Stone roads may require access to mountains to build, from which to quarry the stones. Asphalt roads would require access to oil and if the supply of oil is severed then the roads should be reduced in effectiveness. With Railroads you need coal and steel to build but you need a constant supply of coal to maintain. If you run out then the railroads should become utterly useless.
Just some thoughts...