Dummy city building option

Recently I had an idea of how I can improve my city map and get to inc buildings and tax returns but for that I had to assume some of the areas and draw it on paper and calc some of the road coverages. So if there can be an option that lets you build a dummy city where you don't have to worry about sims happiness rather you can focus on services and polution coverages and you can have better ways to improve city with your imagination.