A great first step would be using scrolling textures, probably. http://blog.krecha-games.com/scroll-image-extension-for-starling/
Or possibly if you need a curved road, something like this (AS3 but not starling) http://gamedevelopment.tutsplus.com/tutorials/create-a-glowing-flowing-lava-river-using-bezier-curves-and-shaders--gamedev-919