Pedestrian Realm: Filters at the top help you isolate Large Trees, Small Trees, Transit Stops, and many other things. These appear on both Background and Foreground so you can layer multiple objects, then move objects left/right.
Medians: Median dialog is very similar, but intended for objects that can be in the center of the road (including cars and pedestrian refuge areas). See medians after this dialog below.
Median Dialog: Below are a few of the icons of this dialog that are not found in the list above. However, the Median dialog also includes many from the list above, but they are not repeated below. Try adding a tree as background, then one of these below as foreground.
Median Markings: Below are some markings available for the median.