Imagine yourself tracing a set of paths that covered every street in a large metropolis, obeyed traffic orientation in every street, and were readable by others

Imagine yourself tracing a set of paths that covered every street in a large metropolis, obeyed traffic orientation in every street, and were readable by others. No further Requirements. As many or as few paths as you'd like, no worries about efficiency, sure you can go through the same streets many times if it helps. But needs to cover every street, obey orientation, and be readable by others. Does not sound easy, does it? Now, let's add a few more Requirements...