To me it looks too random. Street don't really develop randomly with out central planning they develop between the shortest/easiest two points to destinations. and then they further bifurcate from there. So in the meantime new buildings or farms may be built which block possible shortest routes to lesser destinations and so on. So as the streets become less and less major they are going to be more and more detailed in their meanderings, but still not random. With a perfectly flat surface such as the bridge you describe where roads have no obstacles to avoid they would be actually web like, with a central radiating point (or most likely several of them) and streets radiating out from the middle and with cross streets joining up the spokes of the web (or webs).