The line has been operational since 1990, it was a special line because it ran as a metro between Amsterdam Central and Amsterdam South and there, this line continued as a fast tram to Amstelveen. Now, the route will be converted into a high-quality tram connection between Amstelveen Westwijk and Amsterdam Zuid.
More info https://rails.arcelormittal.com/products/transport-rails
Picture: ETS Spoor