The end? yes and no

This afternoon I went on the track up and over a ridge through which the water pipe passes. Came back onto the top of the pipe. I was able to continue on the flat top of the pipe for 200 - 300 before this. The pipe is again underground, and there is no visible track so it was the end as in where I turned around. But the start of the pipe is a considerable distance further on, and the end is back at the pumping station.