What do you have in mind when taking pictures on a highway? Maybe the road signs. Yes, it’s a good idea but here I’m not talking about that.
Road construction requires the creation of a continuous right-of-way, overcoming geographic obstacles and having grades low enough to permit vehicle or foot travel. This means you will find interesting sinuous shapes of roads.
Notice that in most of the cases the road should be free of cars and walkers. Two exceptions are noticeable: the pictures depicting intense city traffic and the night roads when a car leaves behind a rail of light.
As for the composition, it’s always a good idea to start the road from a corner of the picture up to the middle or the other corner. In most of the cases it will appear larger in the starting corner and thinner at the end. However, sometimes, when symmetry allows, you can start and end your road line in the middle of the picture.
As I said many times before, following the weather helps a lot: fog or rain give special effects, and, in the case of train rails, sunrise is also creating a mystical atmosphere.