I stood waiting for my bus for ten minutes yesterday, next to Tlalpan, an extremely busy road. For ten minutes, before I realised that not only were no buses coming past, but no traffic at all. Sometimes I’m a bit slower than….well, the traffic on Tlalpan. I felt it was worth investigating why the traffic had disappeared though. And lo and behold, I found the cause. Many bridges in the city just don’t have any signage to tell truck drivers the maximum height. Probably not worthwhile to be fair. Signs, traffic lights, general rules and other road symbols are observed only on a voluntary basis. There aren’t many volunteers.