How should motorism be included in Civ 4?

[Odin]

cottages/hamlets/villages should grow faster when connected to thier city by highways, representing the rapid growth of Suburbia. Highways connecting cities in the trade network should allow an extra trade route per city.

[Addled Platypus]

just dont foget the un-healthy aspect

make this a worker action? you choose exactlly where it goes

hope this can not be exploited

[byrath]

I wouldn't mind seeing +1 road movement added as a tech benefit, just like engineering does earlier.. but it is probably just as well to leave it alone.