What can be referred to as a center line, is in Redbex an axis.
By importing an axis, the axis can be visualized on the map and it will also become possible to add observations to this axis.
Here's a simple axis representing a tunnel on the island of Södermalm in Stockholm.
Go to your Domain context, right click Axis and choose Add axis.
Before you can upload i file of coordinates, you must choose a coordinate system and click save. That will enable the upload file button.
If you don't have a file with an axis, you can use this very simple axis of 750 meters. Upload this through the File Depot and voliá, we have an axis.
After we have the axis we should a reference system to this axis. The reference system exists so that we for example can reverse the direction of the axis. If we simply want to keep the direction in the file, we can simple name the reference system north.
Give it a name and we should be ready to visualise this on a map. Click add Axis on the map as expected.
To configure an axis you click Configuration on the right hand side of the map. Choose you axis and if you want to, also you reference system. Here we have choosen the reference system and therefor we can also show the chainage along the tunnel.
Please see the reference manual for more information.