Snap Connectors are small prefabs that can be added to other prefabs not necessarily part of the road network.
Imagine a suburbian environment with buildings, car ports/garages and driveways.
It will be time consuming having to align the driveway always with the garage. This a situation where the snap connector is useful by simply adding it to the center of the garage prefab. The driveway can be snapped quickly to this connector just like roads snap to crossing connectors.
This is also useful for side object presets, for examples fences attached to a gate.
To create a snap connector for a road type go to:
General Settings > Road Types
Or in Unity 2018.3+ from the project folder:
/Assets/EasyRoads3D/_Preset Editors/Road Types
Select the specific road type from the Road Types dropdown, scroll downwards to the bottom and press "Create Snap Connector"
The new Snap Connector prefab will be saved in /Assets/EasyRoads3D/prefab sources/Snap Connectors/
The final step is to open the prefab where the Snap Connector will be used, add the connector prefab and position it. Import here is also the rotation. The orientation should be in the direction of the attached side object.