This is very much like the gutter and kerb machine in another thread, just that it has a different mold on it.
I had only previously seen the top of the finished slot drainage channel as I was trimming the stone fill at its sides ready for blacktop.
I was to see it had a bit hole up the middle, thought that you might be as suprised as me.
The last pic shows the air blower that keeps the tube inflated while the concrete sets, it runs off a normal site compressor. Once the concrete is set the tube is deflated and removed threw the slot on top.
When the channel is finished the mold will be changed and the concrete barrier will be formed.