April 9, 2018 by Jim Brennan
It was a typical winter evening in Pittsburgh, Pennsylvania (USA): cold and windy, with lingering precipitation on the ground. As I left work I stuck my hands deep into my coat pockets and hurried to my car. Looking ahead, I saw a gleam on the parking lot – possibly ice; the evening conditions made it difficult to see the pavement well. The risk of a slip and fall was very real.