The Toolbar’s Settings menu has the following features:
Show Scene View Icons: Roads have icons hovering over them that the level designer can click on to toggle street-side elements, such as trees and sidewalks, on/off. This setting shows or hides those icons.
Speed Limit Unit: Traffic speed limits can be set to be displayed in either kilometers per hour or miles per hour.
Auto-regenerate Traffic: As you modify your road network, auto-regeneration will keep NPC traffic properly updated. Disabling this will allow you to manually tweak certain properties (such as the specific position of a lane on a street) that would otherwise get reverted back into default values by auto-regeneration.
Show Valid Traffic Lanes: Road lane configurations can sometimes become invalid if traffic is set to drive both ways on a single lane. This setting will help in locating such issues.