Just a note. Roads do not appear in many scenarios. They are often abstracted away because they have no real benefit to the scenario except to pretty it up (besides the additional movement point that is rarely relevant except in breakthrough format IMO, and then not really anyway). So I wouldn't base a unit rule on the existence of road tiles in a scenario.
rules in scenarios can be very helpfull is my experience. Infantry becomes "special forces" when moving on a road to attack. you can close the distance to your enemy in one turn and still attack.