Transportation view
In this view you see all your communication lines. Including bus lines, metro and railway.
Communication allows you to greatly improve your roads bandwidth, so you should take some interest in it at the point of planning your districts so that you will avoid any trouble with it in the future.
You can name and color lines as you like by clicking on one of buses of that line and picking the "Modify line" option. You can do the same with metro.
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