What distinguishes the line from other things in the image? For example, could the images ever contain other cars that might happen to be the same color as the lines on the road?
Are the lines always the same hue, or does the hue vary according to how old and warn the line is? Are the lines sometimes yellow and sometimes white? Are the lines continuous, or could they be dashed such as to indicate areas that passing is allowed? How do you want to treat locations where the main traffic is to go in one direction, but there are secondary lines on the road to indicate the flow for turning traffic?
How consistent is the line brightness with external light conditions? How consistent is the hue with external light conditions? For example does it show up as a different color in sunlight than in car headlights?
