Pipework

I was quite intrigued - mainly on the Walsall canal - to notice a number of pipe bridges. Nothing unusual about them in themselves, except that the arms that they crossed had been filled in, and the bridges they followed had been bricked up - yet the pipe bridges themselves had apparently been renewed relatively recently.

I wondered why, rather than rebuilding the pipe bridge, with all its vulnerabilities and attendent anti-climbing paraphernalia, they hadn't just re-run the section of pipe buried in the towpath, like the rest of its length.

I can only think it's because  the way the pipe is buried under and incorporated in the the foundations and abutments of the bridge makes this prohibitively difficult.  And so the pipe bridge becomes the ghost of the former bridge itself.