Cross sections require some work no matter which tool you use. Even if we had decals for roads you would need the right texture for cross sections. Now that you mention you want to make a city i recommend using blueprints instead of landscape splines. It will still need you to model the cross sections but in the end it will give you more customization options. Here is an example i created based on the fence BP in Content Examples project:
You can add street lights, parking lots, etc. more easily this way.