I was a little confounded by the author's point about guardrails often being on the outside of sidewalks. It was only when I copy/pasted the URL for the article that they were quoting that I realised that they both had it arse-about-face and actually meant that guardrails are often on the _inside_ of the sidewalk. The outside of a sidewalk (path in this part of the world) would be the bit that borders the road, surely.