Line from outside Brenham to around Waller?

There is a, for lack of better word, line of some sort in the space between the highway that extends quite a ways. I can’t recall exactly where it starts but pretty early on from the drive to Brenham to maybe a few exits before Buccees. At the moment it looks like a super slim sidewalk (which I know it isn’t, just giving a visual) and every so often there is a tiny box on the end caps of some of the lines. I attempted to google it and wasn’t very successful, any insight would be appreciated!